Challenges of Solid Waste Management in Kisumu,Kenya

Solid waste management is a major environmental and public health concern in many urban areas of developing countries. Kisumu like many urban areas of developing countries is grappling with increasing waste generation, an overflowing dumpsite and pollution from uncontrolled discarding of waste. Sustainable solid waste management has remained elusive in the City due to lack of adequate funding and skilled personnel besides poor public attitude towards waste management. Efforts abound to improve the situation but significant progress is hindered by the difficulties in relocating Kachok dumpsite. Recommendations are made for a sustainable solid waste management system supported by a suitably relocated Kachok dumpsite.     

Friction and Wear Characteristics of Single Crystal Ni-Based Superalloys at Elevated Temperatures

The purpose of this study was to investigate the friction and wear behavior of single crystal superalloys at elevated temperatures. Pin-on-plate experiments were conducted using a custom-built high-temperature fretting/wear apparatus. Measurements were performed on two single crystal Ni-based alloys and Waspaloy^® (used as a baseline material). The coefficient of friction for the single crystal materials (i.e., during running-in and steady state) was lower compared to the Waspaloy^®. In addition, the experiments showed that the friction coefficient of the single crystal is dependent on the crystallographic plane; the friction coefficient was lower for the tests on the {100} plane compared to the {111} plane. The wear behavior was aligned with the friction behavior, where the single crystal Ni-based alloys showed slightly higher wear resistance compared to the Waspaloy^®. Ex situ analysis by means of FIB/SEM and XPS analysis revealed the formation of Co-base metal oxide layer on the surface of the single crystal alloy. Similarly, a Co-base oxide layer is observed on the counterface providing a self-mated oxide-on-oxide contact and thus lower friction and wear compared to the Waspaloy^®.     

Development of high-resolution real-time sub-ppb ethane spectroscopy and some pilot studies in life science

We describe a high-resolution real-time spectroscopy system targeted to ethane gas with sensitivity > or = 70 ppt and response time from > or = 0.7 s. The measurement technique is based on a mid-IR lead-salt laser passing through a Herriott cell through which a gas sample flows. We compare wavelength scanning and locked configurations and discuss their relative merits. The technology has been motivated by clinical breath testing applications, ethane being widely regarded as the most important breath biomarker for cell damage via free-radical-mediated oxidative attack. We discuss preliminary human and animal studies in which ultrasensitive real-time ethane detection offers new diagnostic and monitoring potential.     

Selection strategy for site-directed mutagenesis based on altered beta-lactamase specificity

Conventional approaches to oligonucleotide-directed mutagenesis rely upon the application of a selection strategy to maximize mutagenesis efficiencies. We have developed a mutagenesis procedure that incorporates a novel antibiotic resistance for selection. The selection involves altering the substrate specificity of TEM-1 beta-lactamase, the enzyme responsible for bacterial resistance to beta-lactam antibiotics such as ampicillin. The gene encoding beta-lactamase is commonly found on cloning and shuttle vectors used in molecular biology. Amino acid substitutions in several active site residues of beta-lactamase result in increased hydrolytic activity against extended-spectrum penicillins and cephalosporins. This increased activity confers a novel resistance specific to the mutant and thus provides the basis of the selection strategy. We describe a simple and efficient mutagenesis procedure and its application to creating a range of oligonucleotide-directed mutants.     

The Potential Importance of Mine Sites for Biodiversity

Abstract  Abandoned mine sites are typically viewed as environmental problems due to their negative impacts on local ecosystems. This paper presents an alternative viewpoint providing evidence of the potential importance of mine sites for supporting rare and threatened species from many of the major taxonomic orders. The potential importance of these species in remediation of polluted environments is also highlighted.     

Effects of intermittent cycle exercise on intramyocellular lipid use and recovery

The purpose of this investigation was to compare intramyocellular lipid (IMCL) changes in skeletal muscle in nine moderately trained subjects after 45 min of interval cycling and through 1 h of recovery. The exercise session was continous with alternating cycling intensity achieving 50 (3 min) and 110% (2 min) of ventilatory threshold. Spectra from the vastus lateralis were acquired before, immediately after, and 60 min following exercise using a 1.5 T Signa whole-body magnet (point-resolved spectroscopy sequence, echo time 60 ms, transverse relaxation time 2000 ms, 128 acquisitions, and 20 mm³ voxel). Immediately following exercise, IMCI concentration decreased 38% compared to pre-exercise levels (P<0.05). Fitness level and baseline IMCL were not correlated with changes in IMCL following exercise (P>0.05). In the 60-min recovery, IMCL was reduced 30% compared to baseline (P<0.05) and did not recover. In contrast, a nonexercising control group showed no change in IMCL. Our results suggest that IMCL decreased significantly following 45 min of interval cycling, with little recovery in the hour following.