The lysosomal stabilizer and anti-malarial agent, chloroquine, stimulated the respiration and motility of fresh and aged bovine spermatozoa stored in vitro. Duplication of these effects by the phosphodiesterase inhibitors, theophylline and caffeine, suggested that enhancement of sperm activity by chloroquine may be mediated by cyclic AMP.
Exposure to light of bovine spermatozoa suspended in various media results in a progressive decline in metabolic activity followed by the premature death of the cells. The inhibitory and spermicidal effects of visible light resemble a photodynamic action; the photosensitizer is an intrinsic component of the cell.
A new technique for producing silicon ribbons for solar-cell substrates is described. The process begins with inexpensive, 98% pure silicon that is crushed and acid leached to raise the purity to 99.9%. This powder is spread on a graphite plate and electron-beam annealed to form a flat, self-supporting "preribbon." After removal of the graphite and unmelted powder, the preribbon is given a second electron-beam scan that recrystallizes the silicon into a smooth polycrystalline ribbon. This zone melting further improves the purity to over 99.99%. Ribbons 0.4 mm thick and up to 16 mm wide were produced in this initial work. The ribbons are p-type, 0.07 R. cm, and have long crystals about 1 mm wide. Electron-diffusion lengths of 20-30 p m were measured. Calculations indicate that solar-cell efficiencies up to 13% should be possible. If the process can be scaled up and automated, the cost of volume production could be as low as 43 cents/W. It is concluded that the process has the potential for achieving low-cost "solar-grade" substrates and has advantages over other processes. Further work is planned.On dCcrit une technique nouvelle pour la production de rubans de sil~ce utilisCs comme couches de support dans les piles solaires. Le procCdt utilise au depart du silicium h 98%, peu dispendieux, qui est Ccrast et attaqut a I'acide pour porter le degrt de puretC ? i 99,9%. La poudre obtenue est Ctendue sur une plaque de graphite et recuite par un faisceau d'Clectrons pour former un "prC-ruban" plat et capable de se tenir sans support. Aprks enlevement du graphite et de la poudre non fondue, ce prC-ruban est de nouveau balayC par un faisceau d'Clectrons qui recristallise le silicium en un ruban polycristallin rkgulier. Cette fusion par zones amCliore encore la purett, au dela de 99,99%. Des rubans ayant 0,4 mm dlCpaisseur et jusqu'h 16 mm de largeur ont ttC produits dans ce travail init~al. Ces rubans sont de type p , ont une rtsistivite de 0,07 Re cm et contiennent des cristaux allonges larges de 1 mm environ. Des longueurs de diffusion dlClectrons de 20 h 30 p m ont CtC mesurees. Les calculs indiquent qu'on pourrait obtenir des rendements de piles solaires allant jusqu'h 13%. Si le procCdC peut Stre exCcutC h plus grande Cchelle et automatisk, le coDt de production en grande quantitk pourrait &be aussi bas que 43 cents/W. On conclut que le procCdC peut fournir a faible coDt des couches de support de qualit6 "solaire" et qu'il prtsente des avantages sur d'autres procCdCs. On se propose de pousser plus loin ce travail. [Traduit par le journal] Can. J Phys 63, 859 (1985)
It has been pointed out by a number of investigators, notably Lardy and Phillips ('43) and MacLeod ('41), that studies on the metabolism of ejaculated spermatozoa must be carried out using cells removed from, and washed free of the seminal fluid which normally bathes them. Except for the measurement of endogenous oxygen consumption by Lardy and Phillips ('43), and a more recent report by van Tienhoven ('60), work on cock sperm metabolism has involved the use of whole semen. Bogdonoff and Shaffner ('54) reported that the optimum pH for respiration, as measured by methylene blue reduction, of chicken semen was near 7. Zayat and van Tienhoven ('59) presented ZO?. values for cock semen before and after storage for 24 hours at 5°C in three different diluents. Kosin ('44) reported QoZ, and Qw" values, and succinate stimulated respiration of cock semen before and after X-irradiation. Later the oxidative and glycolytic activity of turkey semen was investigated (Kosin, '58), and it was suggested that quantitative aspects of oxidative activity in semen from this animal were similar to those of chicken sperm. Almost nothing is known about the metabolic characteristics of the cock spermatozoan per se. Certainly, the biochemical data obtained with these cells suspended in such a complex and undefined medium as seminal plasma are difficult to interpret, and differ considerably, as will be indicated in the present report, when compared with studies on washed cells.The present investigation is concerned with the respiration and aerobic and anaerobic glycolysis in fowl spermatozoa. In addition, data is presented suggesting breed differences in metabolism which may be of genetic significance. METHODSCock semen was collecteda by the massage technique of Burrows and Quinn ('37). For most experiments ejaculates from several birds were pooled before use in order to avoid individual variation inherent in the semen from any given animal. The cells were concentrated by gentle centrifugation (700 X G for 15 minutes) and washed two times in a calcium-free Krebs Ringer's phosphate buffered at pH 7.1 (Umbreit et al., '51).Oxygen consumption of the sperm suspension (3.0 ml final volume) was measured at 37°C in air, using the conventional Warburg apparatus according to the usual procedures (Umbreit et al., '51). The cells were placed in the sidearm of the flask and tipped into the main compartment after a 10-1 5 minute equilibration period.Glucose utilization and lactic acid production were used as criteria of glycolytic activity and were determined in Ba(OH)2-ZnSOd filtrates of the incubates. Anaerobiosis was attained by gassing the flasks for 10 minutes with commercially prepared specially purified (99.99% ) nitrogen, while shaking in the constant temperature bath at 37"C, after which, at zero time, the cells were tipped into the main compartments of the flasks.Glucose was estimated by the NelsonSomogyi (Somogyi, ' 5 2 ) colorimetric procedure. Lactic acid was determined by the method of Barker and Summerson ('41).
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