Reaching rural customers : The challenge of market-based rural electrification

The large number of households that need catering for in market based approaches to rural energy supply in developing countries makes different demands on all involved players: an extensive infrastructure for reaching the rural customer needs to be established, extensive investments have to be realised, financial sustainability must be assured, and the business must even show profit. Thus, for successful market and infrastructure development it is a major necessity to understand the mechanisms involved. Dorothee Reinmüller, International Solar Energy Society (ISES), Germany and Rana Adib, Fraunhofer Institute for Solar Energy Systems ISE, Germany describe a new guide to assist governments, business, and financing organisations in providing energy to rural areas using renewables.     

Non-volatile reaction products from linoleic acid. Comparison of a ground pea suspension with a purified pea lipoxygenase

Summary Ground ripe and freeze-dried half-ripe peas were aerobically incubated with linoleic acid (pH 6.5, 15°C, 20 min). The following reaction products were isolated and identified: oxodiene-, epoxyhydroxy-, mono, di-, and trihydroxy fatty acids. These compounds were also produced when linoleic acid was incubated with a purified lipoxygenase isoenzyme (isolated from peas). By decreasing the lipoxygenase concentration, relative to the substrate, the number of reaction products also decreases: di- and tri-hydroxy acids no longer appear. Fewer mono- and epoxyhydroxy acids compared with hydroperoxides are formed at decreasing enzyme concentrations. However in all the experiments these two compounds were the main products of lipoxygenase catalysis. The hydroperoxides are not the precursors of the monohydroxy and epoxy acids.

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Nicht-flüchtige Reaktionsprodukte aus Linolsäure. Vergleich einer Erbsenmehlsuspension mit einer gereinigten Erbsen-Lipoxygenase

Zusammenfassung Gemahlene reife und gefriergetrocknete halbreife Erbsen wurden aerob mit Linolsäure incubiert (pH 6,5; 15°C; 20 min). Als Reaktionsprodukte wurden isoliert und identifiziert: Ketodien-, Epoxyhydroxy-, Mono-, Di- und Trihydroxyfettsäuren. Diese Verbindungen entstehen auch, wenn Linolsäure mit einem gereinigten Lipoxygenase-Isoenzym (isoliert aus Erbsen) incubiert wird. Bei relativ zum Substrat abnehmender Lipoxygenasekonzentration sinkt die Zahl der Reaktionsprodukte: Di- und Trihydroxysäuren treten nicht mehr auf. Relativ zu den Hydroperoxyden werden bei sinkender Enzymkonzentration weniger Mono- und Epoxyhydroxysäuren gebildet. In allen Versuchen waren diese beiden Verbindungen aber die Hauptprodukte der Lipoxygenase-Katalyse. Die Hydroperoxyde sind nicht die Vorläufer der Monohydroxy- und Expoxysiiuren.

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Dedicated to Professor Dr. S. W. Souci on his 70th birthday.

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We are grateful to the Deutsche Forschungsgemeinschaft Bonn-Bad Godesberg for supporting this work.     

Genetic variants of human erythrocyte glucose 6-phosphate dehydrogenase: new variants in West Africa characterized by column chromatography

Seven calves seven to 30 days of age were given Mycoplasma bovis antigen by different routes. Immunization was in two phases. The first consisted of single or multiple SC, IV or oral doses of antigen for two to four weeks. The second phase consisted of multiple SC or ID injections given from the eighth to the 19th week. The experiment was terminated at 26 weeks. Antibody titers were followed by indirect hemagglutination, growth inhibition and tetrazolium reduction inhibition. Total serum protein, protein fractions and IgG and IgM concentrations were determined in serums of one calf and the distribution of indirect hemagglutination antibodies in IgG and IgM classes were determined in serums of two of the calves. Indirect hemagglutination titers of 1280 and peak titers of >20,480 occurred after the first and second phases respectively. There was no relationship between total serum IgG or IgM concentrations and indirect hemagglutination titers. In one calf given M. bovis antigen in one dose SC and five weekly doses IV in phase I, indirect hemagglutination antibodies appeared in IgM within one week and IgG by four weeks, IgG antibody activity rose steadily until the 17th week but declined at the 26th week, whereas IgM activity after the initial rise dropped at the 13th week but rose even higher as a result of second phase ID injections. Another calf given six weekly IV doses of M. bovis antigen in phase I developed indirect hemagglutination antibodies in IgM peaking at four weeks then declining but with no IgG response. Activity in both IgM and IgG occurred after the second phase. Growth inhibition antibodies were found only on two occasions in one calf serum and tetrazolium reduction inhibition activity when tested never gave titres exceeding 1:32.     

Mechanical properties of individual electrospun polymer-nanotube composite nanofibers

Singlewalled carbon nanotube/polyvinylalcohol composite nanofibers were electro-spun onto a silicon surface pre-patterned with trenches. These nanofibers were prepared with different loadings of SWCNTs and had radii between 20 and 40 nm. Individual fiber sections were pinned across the trenches and laterally loaded by an AFM tip to yield mechanical response curves. A simple model was exploited to extract the tensile mechanical properties from the lateral force-displacement data. Depending on the fiber composition, the tensile modulus was found to be between 3 and 85 GPa. In addition we have prepared fibers with tensile strength of up to 2.6 GPa. Such optimised fibers break at strains of ∼4% and exhibit toughness of up to 27 MJ/m³.     

Short communication: The effect of calcium supplementation at calving on neutrophil function

Low total blood calcium concentration after calving has been demonstrated to be a risk factor for reduced neutrophil function. The objective of this study was to evaluate whether administration of an injectable calcium supplement product soon after calving increased neutrophil oxidative burst or phagocytosis capacity. Cows (n = 27) from 4 farms were blocked by parity and randomly assigned to receive either calcium gluconate (35% wt/vol) in combination with calcium glucoheptonate (10% wt/vol; Theracalcium, Vétoquinol Canada Inc., Lavaltrie, Quebec, Canada) or a placebo within 12 h after calving and again 24 h later. Each dose of 120 mL was injected subcutaneously over 2 sites. Total serum calcium concentration, neutrophil oxidative burst, and neutrophil phagocytosis capacity were measured from coccygeal blood samples before (time 0) and 72 h after first treatment. There was no difference between treatment groups in lactation number, total calcium concentration, oxidative burst, or phagocytosis at time of enrollment. There was no effect of treatment on oxidative burst or phagocytosis by neutrophils. This preliminary study does not support an effect of supplemental calcium to improve neutrophil oxidative burst or phagocytosis capacity of low-parity parturient cows.