Dialkyldithiophosphate Acids (HDDPs) as Effective Lubricants of Sol–Gel Titania Coatings in Technical Dry Friction Conditions

The goal of this study was the investigation of the effectiveness of dialkyldithiophosphate acids (HDDPs) films in improving the tribological properties of thin, sol– gel derived titania coatings. Amorphous, anatase, and rutile titania coatings were obtained using sol–gel dip–coating deposition after treatment at 100, 500, and 1,000 C, respectively. Titania coatings were then modified from the liquid phase by HDDPs acids having dodecyl-(C12), tetradecyl-(C14), and hexadecyl-(C16) alkyl chains deposited by dip–coating (DC) and Langmuir–Blodgett (LB) methods. The influence of the deposition procedure, the length of the HDDPs alkyl chain and the type of titania substrate on the surface morphology and tribological properties were studied. It was found, using wetting contact angle measurements, that these modifications of titania coatings decrease the surface free energy and increase its hydrophobicity. The surface topography imaged by Atomic force microscopy (AFM), exhibit island-like or agglomerate features for the DC deposition method, while smooth topographies were observed for LB depositions. Tribological tests were conducted by means of a microtribometer operating in the normal load range 30–100 mN. An enhancement of tribological properties was observed upon modification, as compared to unmodified titania

Evaluation of heavy metals in the soils of urban and peri-urban irrigated land in Kano, Northern Nigieria

Smallholder irrigation for the production of market gardening is important in urban and peri-uban Kano in northern Nigeria. This involves the use of polluted stream water flowing along the major streams in the city. Three streams were selected based on their source of pollutions: Domestic and industrial sources and an ideally non-polluted stream was used as Control. Soil samples were collected from these irrigated sites and analysed for some selected heavy metals including cadmium, chromium, zinc manganese, iron, copper and nickel. The results were compared with the control site and the European Regulatory Standard (EURS). It was found that all the seven heavy metals are higher in the Domestic source pollution (DSP) than in the Industrial source pollution (ISP), prominent among them are Zn, Cu, Fe and Ni, of which their main source is domestic sewage sludge. The high concentration of Cd, Ni and Zn could be associated with tyre wear and combustion of petroleum from the heavy traffic prevalent in this part of the city. The Industrial source pollution stream was found to be less polluted in Mn and Fe which are even less than the control site. There is also continuous accumulation of Fe, Mn and Zn in the DSP sites, this is possibly due to heavy disposal of domestic sewages along the stream. However, the mean concentration of all the heavy metals with the exception of Cd were found to be lower then the European Regulatory Standard, thus there is urgent concern for the authority to look into the continuous accumulation of Cd in especially DSP sites, where the values were above the European Regulatory Standard. Cd can reach human body through crop uptake to the people that consume the crop, this may cause heart and kidney disease. Keywords: Heavy Metals, Domestic Source Pollution (DSP), Irrigated Land, Industrial Source Pollution (ISP) European Regulatory Standard (EURS

Random Antiferromagnetic Spin-1/2 Chains with Competing Interactions

We study disordered antiferromagnetic spin-1/2 chains with nearest- and further-neighbor interactions using the real-space renormalization-group method. We find that the system supports two different phases, depending on the ratio of the strength between nearest-neighbor and further-neighbor interactions as well the bond randomness strength. For weak further neighbor coupling the system is in the familiar random singlet phase, while stronger further neighbor coupling drives the system to a large spin phase similar to that found in the study of random antiferromagnetic-ferromagnetic spin chains. The appearance of the large spin phase in the absence of ferromagnetic coupling is due to the frustration introduced by further neighboring couplings, and is unique to the disordered chains.Comment: 11 pages, 7 figure

The Role of Head Teacher in Improvisation and Maintenance of School Plants

The conditions and situation of the physical and infrastructural facilities in the primary schools had marred the attainment of the goal of education for all. The present Primary Education Commission (UPEC) 1999/91 survey indicated that approximately 4.9% of Nigerian primary school have no building, while the survey equally shows that the is a short fall of 64.2% in pupils furniture and 62.5% in teachers' and non teaching furniture, nationwide. It also stressed further that equipment for teaching sciences, sports, Home Economics creative Arts were lacking in majority of the Primary Schools. Moreover, the above situations seem not to have improved in the recent times. Many of the primary school buildings are dilapidated, displaying no window panes or Shutters, no ceilings, plaster peel offs, broken floors and leaking roofs. Poor as these structures are, they are not even adequate and thus two or more streams have to use the same dilapidated class in many cases. This has resulted into overcrowded classrooms with serious implications for teaching and learning in the primary schools in Nigeria. It is against this backdrop that this paper examines the role of head teacher in improvisation and maintenance of school plants in primary schools.Keywords: Primary Education, Head Teacher, School Plants, Physical facilities and infrastructural facilitie

The Potential of Some Plant Powders as Biopesticides against Sitophilus Zeamais (Motsch.) (Coleoptera: Curculionidae) and Callosobruchus maculatus (F.) (Coleoptera: Bruchidae) On Stored Grains: A Review

Powders prepared from parts of different plant species indigenous to Nigeria were tested by various Nigerian scientists under laboratory conditions for their insecticidal activities against the common insect pests of maize and cowpea, i.e. Sitophilus zeamais and Callosobruchus maculatus during storage. Results showed that at certain concentrations, the plant materials had both ovicidal and larvicidal effects. They also reduced adult emergence, progeny development and increased mortality of the adults. Some have anti-feedant effects on the insect pests. Looking into the side effects of synthetic pesticides, the studies demonstrated that these plant parts can play an important role in protection of stored grains from insect invasion during storage.Key words: Biopesticides, Callosobruchus maculatus, Plant powders, Sitophilus zeamais Stored grain

Chronic psychosocial and financial burden accelerates 5-year telomere shortening: findings from the Coronary Artery Risk Development in Young Adults Study.

Leukocyte telomere length, a marker of immune system function, is sensitive to exposures such as psychosocial stressors and health-maintaining behaviors. Past research has determined that stress experienced in adulthood is associated with shorter telomere length, but is limited to mostly cross-sectional reports. We test whether repeated reports of chronic psychosocial and financial burden is associated with telomere length change over a 5-year period (years 15 and 20) from 969 participants in the Coronary Artery Risk Development in Young Adults (CARDIA) Study, a longitudinal, population-based cohort, ages 18-30 at time of recruitment in 1985. We further examine whether multisystem resiliency, comprised of social connections, health-maintaining behaviors, and psychological resources, mitigates the effects of repeated burden on telomere attrition over 5 years. Our results indicate that adults with high chronic burden do not show decreased telomere length over the 5-year period. However, these effects do vary by level of resiliency, as regression results revealed a significant interaction between chronic burden and multisystem resiliency. For individuals with high repeated chronic burden and low multisystem resiliency (1 SD below the mean), there was a significant 5-year shortening in telomere length, whereas no significant relationships between chronic burden and attrition were evident for those at moderate and higher levels of resiliency. These effects apply similarly across the three components of resiliency. Results imply that interventions should focus on establishing strong social connections, psychological resources, and health-maintaining behaviors when attempting to ameliorate stress-related decline in telomere length among at-risk individuals

Ecological risk assessment of heavy metals pollution on irrigated soil along Salanta River Valley, Kano State Nigeria

This paper assessed the heavy metals pollution in irrigated soil of salanta river valley of Sharada industrial area with aim of assessing the potential ecological risk of Cd, Cu, Cr and Zn. Soil samples were collected from five plots randomly selected along the stream and heavy metals (Cd, Cu, Cr and Zn) and pH were analyzed using Atomic Absorption Spectrophotometer and pH meter respectively. The mean values and standard deviation of heavy metals in the study area shows that there is variation in the mean values among the heavy metal in the study area in which Cr recorded mean values of 2.30mg/kg ± 0.45, Cu 1.01 mg/kg ±0.78, Cd 3.02 mg/kg ± 0.66, Zn 26.4 mg/kg± 5.45 and mean pH 6.8 ± 0.51. The Cd, Cu and Zn were found below European regulatory values, the mean value of Cd (3.02mg/kg) is found above EU regulatory values (3.0mg/kg) and the pH value of the study area shows that the soil is slightly acidic and can influence the availability and solubility of the heavy metals in the area. The assessment also show that Cd (Pij,= 1.0), Cu (Pij,= 0.007) and Zn (Pij,= 0.088) are heavily polluted the soil of the area, and also slightly polluted with Cr (Pij,= 0.025). However, the potential ecological risk assessment show that Cr (Eri = 0.005) and Cu (Eri = 0.003) have low potential ecological risk in the area; Zn (Eri = 0.04) has moderate potential ecological risk while Cd (Eri = 0.088) is considerable potential ecological risk in the soil of study area. It was recommended that the industries should treat their waste water before  discharge and farmers should avoid using waste water directly, sewage sludge and effluent for watering and manure respectively.Key words: Heavy metals, pollution, soil, ecological ris

Overcoming barriers to engaging socio-economically disadvantaged populations in CHD primary prevention: a qualitative study

<p><b>Background:</b> Preventative medicine has become increasingly important in efforts to reduce the burden of chronic disease in industrialised countries. However, interventions that fail to recruit socio-economically representative samples may widen existing health inequalities. This paper explores the barriers and facilitators to engaging a socio-economically disadvantaged (SED) population in primary prevention for coronary heart disease (CHD).</p> <p><b>Methods:</b> The primary prevention element of Have a Heart Paisley (HaHP) offered risk screening to all eligible individuals. The programme employed two approaches to engaging with the community: a) a social marketing campaign and b) a community development project adopting primarily face-to-face canvassing. Individuals living in areas of SED were under-recruited via the social marketing approach, but successfully recruited via face-to-face canvassing. This paper reports on focus group discussions with participants, exploring their perceptions about and experiences of both approaches.</p> <p><b>Results:</b> Various reasons were identified for low uptake of risk screening amongst individuals living in areas of high SED in response to the social marketing campaign and a number of ways in which the face-to-face canvassing approach overcame these barriers were identified. These have been categorised into four main themes: (1) processes of engagement; (2) issues of understanding; (3) design of the screening service and (4) the priority accorded to screening. The most immediate barriers to recruitment were the invitation letter, which often failed to reach its target, and the general distrust of postal correspondence. In contrast, participants were positive about the face-to-face canvassing approach. Participants expressed a lack of knowledge and understanding about CHD and their risk of developing it and felt there was a lack of clarity in the information provided in the mailing in terms of the process and value of screening. In contrast, direct face-to-face contact meant that outreach workers could explain what to expect. Participants felt that the procedure for uptake of screening was demanding and inflexible, but that the drop-in sessions employed by the community development project had a major impact on recruitment and retention.</p> <p><b>Conclusion:</b> Socio-economically disadvantaged individuals can be hard-to-reach; engagement requires strategies tailored to the needs of the target population rather than a population-wide approach.</p&gt

Use of stone powder in concrete and mortar as an alternative of sand

Stone powder produced from stone crushing zones appears as a problem for effective disposal. Sand is a common fine aggregate used in construction work as a fine aggregate. In this study, the main concern is to find an alternative of sand. Substitution of normal sand by stone powder will serve both solid waste minimization and waste recovery. The study focuses to determine the relative performance of concrete by using powder sand. From laboratory experiments, it was revealed that concrete made of stone powder and stone chip gained about 15% higher strength than that of the concrete made of normal sand and brick chip. Concrete of stone powder and brick chip gained about 10% higher strength than that of the concrete normal sand and stone chip concrete. The highest compressive strength of mortar found from stone powder which is 33.02 Mpa, shows that better mortar can be prepared by the stone powder. The compressive strength of concrete from stone powder shows 14.76% higher value than that of the concrete made of normal sand. On the other hand, concrete from brick chip and stone powder produce higher compressive value from that of brick chip and normal sand concrete.Key words: Stone powder, concrete, mortar, concrete, compressive strength

Chronic non-specific low back pain - sub-groups or a single mechanism?

Copyright 2008 Wand and O'Connell; licensee BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.Background: Low back pain is a substantial health problem and has subsequently attracted a considerable amount of research. Clinical trials evaluating the efficacy of a variety of interventions for chronic non-specific low back pain indicate limited effectiveness for most commonly applied interventions and approaches. Discussion: Many clinicians challenge the results of clinical trials as they feel that this lack of effectiveness is at odds with their clinical experience of managing patients with back pain. A common explanation for this discrepancy is the perceived heterogeneity of patients with chronic non-specific low back pain. It is felt that the effects of treatment may be diluted by the application of a single intervention to a complex, heterogeneous group with diverse treatment needs. This argument presupposes that current treatment is effective when applied to the correct patient. An alternative perspective is that the clinical trials are correct and current treatments have limited efficacy. Preoccupation with sub-grouping may stifle engagement with this view and it is important that the sub-grouping paradigm is closely examined. This paper argues that there are numerous problems with the sub-grouping approach and that it may not be an important reason for the disappointing results of clinical trials. We propose instead that current treatment may be ineffective because it has been misdirected. Recent evidence that demonstrates changes within the brain in chronic low back pain sufferers raises the possibility that persistent back pain may be a problem of cortical reorganisation and degeneration. This perspective offers interesting insights into the chronic low back pain experience and suggests alternative models of intervention. Summary: The disappointing results of clinical research are commonly explained by the failure of researchers to adequately attend to sub-grouping of the chronic non-specific low back pain population. Alternatively, current approaches may be ineffective and clinicians and researchers may need to radically rethink the nature of the problem and how it should best be managed