Nanofiller Fibre-Reinforced Polymer Nanocomposites

In this work, the technology of nano and micro-scale particle reinforcement concerning various polymeric fibre-reinforced systems including polyamides (PA), polyesters, polyurethanes, polypropylenes and high performance/temperature engineering polymers such as polyimide (PI), poly(ether ether ketone) (PEEK), polyarylacetylene (PAA) and poly p-phenylene benzobisoxazole (PBO) is reviewed. When the diameters of polymer fibre materials are shrunk from micrometers to submicrons or nanometers, there appear several unique characteristics such as very large surface area to volume ratio (this ratio for a nanofibre can be as large as 103 times of that of a microfibre), flexibility in surface functionalities and superior mechanical performance (such as stiffness and tensile strength) compared with any other known form of the material. However, nanoparticle reinforcement of fibre reinforced composites has been shown to be a possibility, but much work remains to be performed in order to understand how nanoreinforcement results in dramatic changes in material properties. The understanding of these phenomena will facilitate their extension to the reinforcement of more complicated anisotropic structures and advanced polymeric composite systems

Enhancement of thermal conductivity of materials using different forms of natural graphite.

The quest for improvement of thermal conductivity in every area including aerospace structures is gaining momentum as the modern day technology is embedded with electronics which generate considerable amounts of heat energy. In some other applications, the thermal energy must be absorbed or released at a very fast rate. Natural graphite is highly anisotropic and has excellent thermal and electrical conductivity in a-direction hence; it is one of the potential candidates to enhance thermal conductivity. This paper encompasses various preparation routes used to enhance thermal conductivity in materials/composites using graphite flakes in its natural and treated forms along with characterization results of thermal conductivity and/ or electrical resistivity where available. Addition of graphite has shown to improve thermal conductivity in some materials by 30-130 times whereas one method of preparation described here shows composites to have thermal conductivity as high as 750 W/m K

Late Effects of Therapy, Stigmatization and Social Reintegration following Childhood Cancer Survival in Kenya: A Case Report

Childhood cancer survival is increasing in low- and middle-income countries like Kenya, which comes with a new healthcare challenge: late effects and quality-of-life of survivors. A case was studied to depict a Kenyan Hodgkin lymphoma survivor, illustrating some of the childhood cancer survivors' difficulties in Kenya. Late effects of therapy, stigmatization and social reintegration were explored. The investigators reviewed medical records and used semi-structured interviews and stigma assessments using the Social Impact Scale. The survivor developed severe pulmonary hypertension during treatment with ABVD and salvage protocols. Three years after treatment, the patient experienced chemotherapy-induced late effects (chronic heart disease) that hindered personal care, social activities and job opportunities and required follow-up. Stigmatization by the community burdened his family life and marital prospects. This case report is one of the first that testifies of combined medical and psychosocial challenges that childhood cancer survivors may face in sub-Saharan Africa and underlines the need for a holistic approach

Energy absorption characteristics of nano-composite conical structures.

The effect of the filler material on the energy absorption capabilities of polyamide 6 composite structures is studied in details in the present paper. The axial dynamic and quasi-static collapse of conical structures was conducted using a high energy drop tower, as well as Instron 5500R electro-mechanical testing machine. The impact event was recorded using a high-speed camera and the fracture surface was investigated using scanning electron microscopy (SEM). The obtained results indicate an important influence of filler material on the energy absorption capabilities of the polymer composites. A significant increase in specific energy absorption (SEA) is observed in polyamide 6 (PA6) reinforced with nano-silica particles (SiO2) and glass-spheres (GS), whereas addition of montmorillonite (MMT) did not change the SEA parameter

Factors influencing cervical cancer screening in a Kenyan Health Facility: a mixed qualitative and quantitative study

Background: Cervical cancer is the commonest cause of cancer-related morbidity and mortality among women in developing countries in sub-Saharan Africa. Screening for cervical cancer among HIV infected women is crucial as they are more at risk of developing the disease and progressing faster once infected with Human Papilloma Virus (HPV).Methods: We aimed to determine the factors affecting the utilization of cervical cancer screening among HIV infected women above 18 years of age at Kenyatta National Hospital by conducting a cross-sectional mixed quantitative and qualitative methods study. Descriptive and inferential analysis was carried out on quantitative data to determine significant associations with cervical cancer utilization. Qualitative data were analyzed after coding for significant clauses and transcribing to determine themes arising.Results: Three hundred and twenty eight of the total 387 women enrolled reported they had been advised by their health providers to go for screening. However, only 179 (46%) reported cervical cancer screening.  Women were more likely to report cervical cancer screening if recommendation by a staff was made (p <0.001), and prior to joining KNH CCC (p <0.001). Qualitatively the main barrier to screening included fear of screening due to concerns about excessive pain or bleeding, lack of proper communication on screening procedures and long waiting timeConclusions: The utilization of cervical cancer screening services was low despite high rates of health care recommendation. The women were more likely to utilize the service if recommendation from the health care worker was made, and if they had ever screened before

Tensile and flexural properties of hybrid graphene oxide/epoxy carbon fibre reinforced composites.

In this study, nano-sized graphene oxide sheets were homogenously dispersed via sonication methods in epoxy followed by vacuum resin infusion for the fabrication of the epoxy, graphene oxide (GO) and micro-sized carbon fibre reinforced nanocomposites (EP/CF/GO). Graphene oxide concentrations ranging from 0.1 - 0.5 wt. % were studied to investigate the effect on tensile and flexural strength. It was observed that the tensile strength of the EP/CF decreased with the addition of GO but increased with GO weight concentration in the nanocomposites studied from 498MPa to 519 MPa for the inclusion of 0.1 to 0.5 wt.% GO respectively. The 0.5 wt. % EP/CF/GO recorded a 10% increase in Young's modulus compared to the classical epoxy / carbon fibre composites, and similar trend was observed for the flexural properties. However flexural strength of the GO samples did not surpass the control sample (epoxy /carbon fibre composites) with the 0.3 wt.% GO samples (EP/CF/GO) providing the greatest flexural strength of >580 MPa compared to the 0.1 wt.% and 0.5 wt.% GO samples

Characterization of synthesized polyurethane/montmorillonite nanocomposite foams.

Nanophased hybrid composites based on polyurethane/montmorillonite (PU/MMT) have been fabricated. The nanocomposite which was formed by the addition of a polyol premix with 4,4'-diphenylmethane diisocyanate to obtain nanophased polyurethane foams which were then used for fabrication of nanocomposite panels has been shown to have raised strength, stiffness and thermal insulation properties. The nanophased polyurethane foam was characterized by means of scanning electron microscope (SEM), transmission electron microscope (TEM) measurements and X-ray diffraction (XRD). TEM and SEM analysis indicated that nanophased particles are dispersed homogeneously in the polyurethane matrix on the nanometer scale indicating that PU/MMT is an intercalated nanocomposite with a 2-3 nm nanolayer thickness

A Critical Review of the Leadership Styles on the Performance of Public Secondary Schools In National Examinations In Tana River County, Kenya

In Kenya, many teachers have been elevated to leadership positions without much formal training leading to mismanagement of schools hence poor students’ performance and disappointing results. The kind of leadership style adopted by a leader greatly determines the nature of performance in national examinations. Experience in Kenya reveals that many schools that were once effective in academic performance have lowered their standards due to poor leadership while others have greatly improved through effective leadership. Whereas good leadership initiates and sustains a slow but steady upward spiral, ineffective leadership makes academic standards plummet. The purpose of this study was therefore to examine the impact of principals’ leadership style on the performance of students in public secondary schools in K.C.S.E. The researcher used an explanatory approach based on a descriptive analysis design to establish opinions and knowledge about the impact of principals ‘leadership style on students performance in Tana River County. The study targeted 9 secondary schools in the county that had presented candidates for the national examinations between 2005 &amp; 2009. Both purposive and simple random sampling techniques were used to select a sample of 9 principals and 40 teachers respectively. From this a sample size of 49 respondents was selected for the study. Primary data was collected from the teachers and principals using self administered questionnaires based on the profile of leadership behavior and own behavior. Both inferential and descriptive statistics were used to analyze the data. ANOVA was used to establish the perception of teachers and their principals on leadership styles exhibited by the head teachers. Correlation analysis was used to show the relationship between principals’ leadership styles and student performance in national examinations. The finding of this study strongly indicate a positive relationship between the principals’ leadership styles and students’ performance. Autocratic leadership style was found to have a significant effect on the students’ performance in national examinations. The study recommends the principals to shift to transformative approaches of leadership to enhance good performance of at the national level. The study proposes mandatory leadership training programs for the secondary school principals to update them with modern leadership trends and techniques needed for effective performance

A guideline for the formation of sub-national climate-smart agriculture alliances in Tanzania

About the guideline: This document summarizes recommendations on best practices on how to form and operationalize of sustainable sub-national Climate Smart Agriculture (CSA) alliances for CSA actors in Tanzania. These are based on the experience and recommendations of existing District CSA Alliances and views from selected CSA actors in the country. It seeks to support ongoing efforts in the country to promote the adoption of CSA practices and technologies