Alkali Activated Slag Characterization by Scanning Electron Microscopy and X-ray Microanalysis

Blast furnace slag is a non-metallic byproduct generated by the production of iron and steel in a blast furnace at temperatures in the range of 1400°-1600° C. The alkali activation of blast furnace slag has the potential to reduce the environmental impact of cementitious materials and to be applied in geographic zones where weather is a factor that negatively affects performance of materials based on Ordinary Portland Cement. Alkali-activated blast furnace slag cements have been studied since the 1930s due to its high compressive strength; they can exceed 100 MPa in 28 days. The low Ca/Si ratio in slag improves its resistance to aggressive chemical materials such as acids, chlorides and sulphates. Blast furnace slag is a highly heterogeneous material. It is well known that its chemical composition affects the physical properties of the alkali activated material, however there is little work on how these inhomogeneities affect the microstructure and pore formation. In this study we characterize slag cement activated with KOH using several methods: x-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), x-ray microanalysis (EDS), and quantitative element mapping. Attention is focused on delineating the phases induced by the alkali activation, as these phases are important in determining the mechanical properties of the material. For the alkaline activated slag, we found four phases. One phase was the particles carried over from the unactivated slag, but with significant changes in the chemical composition. In addition, three other phases were found -- one is rich in hydrotalcite and two phases were calcium aluminum silicate hydrate (C-A-S-H) is predominant

The electrification of newly formed clouds of water droplets

A survey of previous work on cloud droplet electrification was carried out. A cloud chamber was constructed and used to generate droplets of radius in the range 1-3 μm. The size and the charge of individual droplets were determined. Positive and negative droplets were observed. The average charge on the droplets was found to be about 5e. Also a photographic method was tried and discussed to determine the charge on the droplets

An Evaluation of Distinct Volumetric and Functional MRI Contributions Toward Understanding Age and Task Performance: A Study in the Basal Ganglia

Prior work by our group and others has implicated the basal ganglia as important in age-related differences in tasks involving motor response control. The present study used structural and functional MRI approaches to analyze this region of interest (ROI) toward better understanding the contributions of structural and functional MRI measures to understanding age-related and task performance-related cognitive differences. Eleven healthy elders were compared with 11 healthy younger adults while they completed the “go” portion of a complex Go/No-go task. Separate ROI\u27s in the bilateral caudate (C) and putamen/globus pallidus (PGp) were studied based upon previous findings of age-related functional MRI differences in basal ganglia for this portion of the task. Structural volumes and functional activation (in percent area under the curve during correct responses) were independently extracted for these ROI\u27s. Results showed that age correlated with ROI volume in bilateral PGp and C, while multiple task performance measures correlated with functional activation in the left PGp. The Go/No-go task measures were also significantly correlated with traditional attention and executive functioning measures. Importantly, fMRI activation and volumes from each ROI were not significantly inter-correlated. These findings suggest that structural and functional MRI make unique contributions to the study of performance changes in aging

Preculturing effect of thidiazuron on in vitro shoot multiplication and micropropagation round in Capparis decidua (Forsk.) an important multipurpose plant

An efficient protocol was developed for clonal multiplication of an important shrub: Capparis decidua (Forsk.) Edgew, through in vitro shoot induction and multiplication from nodal explants. Pretreatment of nodal explants in a liquid Murashige and Skoog (MS) medium augmented with various thidiazuron (TDZ) concentrations at relatively high levels (5–100 μM) for different time duration (4, 8, 12 and 16 d), proved a significant approach for in vitro shoot production. After an initial exposure time to TDZ, nodal explants were inoculated onto a MS basal medium devoid of TDZ for further induction and proliferation. The highest regeneration rate (85%), average number of shoots/explant (8.7 ± 0.22) and maximum shoot length (3.9 ± 0.33 cm) were obtained from the nodal explants exposed to 50 μM TDZ for 8 d. The nodal explants excised from the proliferated cultures of TDZ (50 μM) for 8 d were used as explants and showed an enhancement rate after next three round of in vitro propagation. Best results for rooting was obtained by ex vitro treatment of shoots with 200 μM indole-3-butyric acid (IBA) for 20 min. as it produced an average of 5.7 ± 0.41 roots per microshoot with 4.4 ± 0.39 cm root length in 84% shoots. Different planting substrates was tested for maximum survival of hardening off micropropagated plantlets and soilrite proved most effective than others as 97.1 ± 7.21 plantlets survived. All micropropagated plants grew well in natural conditions and showed similar morphology to the mother plant

A systematic review and meta-analysis of decision-making in offender populations with mental disorder

Decision-making has many different definitions, and is measured in varied ways using neuropsychological tasks. Offenders with mental disorder habitually make disadvantageous decisions, but no study has systematically appraised the literature. This review aimed to clarify the field by bringing together different neuropsychological measures of decision-making, and using meta-analysis and systematic review to explore the performance of offenders with mental disorders on neuropsychological tasks of decision-making. A structured search of Pubmed, Embase, PsycINFO, Medline, Cinahl was conducted with additional hand searching and grey literature consulted. Controlled studies of decision-making in offenders with evidence of any mental disorder, including a validated measure of decision-making were included. Total score on each relevant decision-making task was collated. Twenty-three studies met inclusion criteria (n=1,820), and 10 studies (with 15 experiments) were entered into the meta-analysis (n=841). All studies included in the meta-analysis used the Iowa Gambling Task (IGT) to measure decision-making. Systematic review findings from individual studies showed violent offenders made poorer decisions than matched offender groups or controls. An omnibus meta-analysis was computed to examine performance on IGT in offenders with mental disorder compared with controls. Additionally, two sub-group meta-analyses were computed for studies involving offenders with personality disorder and psychopathy, and recidivists who were convicted of Driving While Intoxicated (DWI). Individual studies not included in the meta-analysis partially supported the view that offenders make poorer decisions. However, the meta-analyses showed no significant differences in performance on IGT between the offender groups and controls. Further research is required to ascertain whether offenders with mental disorder have difficulty in making advantageous decisions. An analysis of cause and effect and various directions for future work are recommended to help understand the underpinning of these findings

Wavelets operational methods for fractional differential equations and systems of fractional differential equations

In this thesis, new and effective operational methods based on polynomials and wavelets for the solutions of FDEs and systems of FDEs are developed. In particular we study one of the important polynomial that belongs to the Appell family of polynomials, namely, Genocchi polynomial. This polynomial has certain great advantages based on which an effective and simple operational matrix of derivative was first derived and applied together with collocation method to solve some singular second order differential equations of Emden-Fowler type, a class of generalized Pantograph equations and Delay differential systems. A new operational matrix of fractional order derivative and integration based on this polynomial was also developed and used together with collocation method to solve FDEs, systems of FDEs and fractional order delay differential equations. Error bound for some of the considered problems is also shown and proved. Further, a wavelet bases based on Genocchi polynomials is also constructed, its operational matrix of fractional order derivative is derived and used for the solutions of FDEs and systems of FDEs. A novel approach for obtaining operational matrices of fractional derivative based on Legendre and Chebyshev wavelets is developed, where, the wavelets are first transformed into corresponding shifted polynomials and the transformation matrices are formed and used together with the polynomials operational matrices of fractional derivatives to obtain the wavelets operational matrix. These new operational matrices are used together with spectral Tau and collocation methods to solve FDEs and systems of FDEs

Characteristics of dental fear among Arabic-speaking children: a descriptive study

BACKGROUND: Dental fear has not only been linked to poor dental health in children but also persists across the lifespan, if unaddressed, and can continue to affect oral, systemic, and psychological health. The aim of this study was to assess the factor structure of the Arabic version of the Children’s Fear Survey Schedule-Dental Subscale (CFSS-DS), and to assess the difference in factor structure between boys and girls. METHODS: Participants were 220 consecutive paediatric dental patients 6–12 years old seeking dental care at the Faculty of Dentistry, King Abdulaziz University, Saudi Arabia. Participants completed the 15-item Arabic version of the CFSS-DS questionnaire at the end of the visit. Internal consistency was assessed using Cronbach’s alpha. Factor analysis (principal components, varimax rotation) was employed to assess the factor structure of the scale. RESULTS: The Cronbach’s alpha was 0.86. Four factors with eigenvalues above 1.00 were identified, which collectively explained 64.45% of the variance. These factors were as follows: Factor 1, ‘fear of usual dental procedures’ consisted of 8 items such as ‘drilling’ and ‘having to open the mouth’, Factor 2, ‘fear of health care personnel and injections’ consisted of three items, Factor 3, ‘fear of strangers’, consisted of 2 items. Factor 4, ‘fear of general medical aspects of treatment’, consisted of 2 items. Notably, four factors of dental fear were found in girls, while five were found in boys. CONCLUSIONS: Four factors of different strength pertaining to dental fear were identified in Arabic-speaking children, indicating a simple structure. Most items loaded high on the factor related to fear of usual dental procedures. The fear-provoking aspects of dental procedures differed in boys and girls. Use of the scale may enable dentists to determine the item/s of dental treatment that a given child finds most fear-provoking and guide the child’s behaviour accordingly. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1186/1472-6831-14-118) contains supplementary material, which is available to authorized users

Screening High School Students for Eating Disorders: Results of a National Initiative

Introduction: Early identification and treatment of disordered eating and weight control behaviors may prevent progression and reduce the risk of chronic health consequences. Methods: The National Eating Disorders Screening Program coordinated the first-ever nationwide eating disorders screening initiative for high schools in the United States in 2000. Students completed a self-report screening questionnaire that included the Eating Attitudes Test (EAT-26) and items on vomiting or exercising to control weight, binge eating, and history of treatment for eating disorders. Multivariate regression analyses examined sex and racial/ethnic differences. Results: Almost 15% of girls and 4% of boys scored at or above the threshold of 20 on the EAT-26, which indicated a possible eating disorder. Among girls, we observed few significant differences between ethnic groups in eating disorder symptoms, whereas among boys, more African American, American Indian, Asian/Pacific Islander, and Latino boys reported symptoms than did white boys. Overall, 25% of girls and 11% of boys reported disordered eating and weight control symptoms severe enough to warrant clinical evaluation. Of these symptomatic students, few reported that they had ever received treatment. Conclusion: Population screening for eating disorders in high schools may identify at-risk students who would benefit from early intervention, which could prevent acute and long-term complications of disordered eating and weight control behaviors