A comparison of the protective action of added egg yolks from five avian species to the cryopreservation of bull sperm

Cryopreservation of domestic animal sperm has been widely used for artificial insemination (AI), and egg yolk is one of the most commonly used cryoprotectants during the freezing-thawing process. The objectives of this study were to compare the effectiven

Characterisation and fluidisation of synthetic pit latrine sludge

Half of the world’s urban population will live in informal settlements or “slums” by 2030. Affordable urban sanitation presents a unique set of challenges as the lack of space and resources to construct new latrines makes the de-sludging of existing pits necessary and is something that is currently done manually with significant associated health risks. Therefore various mechanised technologies have been developed to facilitate pit emptying, with the majority using a vacuum system to remove material from the top of the pit. However, this results in the gradual accumulation of unpumpable sludge in the pit, which eventually fills the latrine and forces it to be abandoned. This study has developed a method for fluidising unpumpable pit latrine sludge, based on laboratory experiments using a harmless synthetic sludge. Such a sludge consisting of clay and compost was developed to replicate the physical characteristics of pit latrine sludges characterised in Botswana during the 1980s. Undrained shear strength and density are identified as the critical parameters in controlling pumpability and a method of sludge characterisation based on these parameters is reported. In a series of fluidisation tests using a one fifth scale pit emptying device the reduction in sludge shear strength was found to be caused by i) dilution, which increases water content, and ii) remoulding, which involves mechanical agitation to break down the structure of the material. The tests demonstrated that even the strongest of sludges could be rendered “pumpable” by sufficient dilution. Additionally, air injection alone produced a three-fold decrease in strength of consolidated samples as a result of remoulding at constant water content. The implications for sludge treatment and disposal are discussed, and the classification of sludges according to the equipment required to remove them from the latrine is proposed. Possible field tests to estimate sludge density and shear strength are suggested. The feasibility of using low cost vacuum cleaners to replace expensive vane pumps is demonstrated. This offers great potential for the development of affordable pit emptying technologies that can remove significantly stronger sludges than current devices through fluidising the wastes at the bottom of the pit before emptying

Characterisation and fluidisation of synthetic pit latrine sludge

Half of the world's urban population will live in informal settlements or ‘slums’ by 2030. Affordable urban sanitation presents a unique set of challenges as the lack of space and resources to construct new latrines makes the de-sludging of existing pits necessary and is something that is currently done manually with significant associated health risks. Various mechanised technologies have therefore been developed to facilitate pit emptying, with the majority using a vacuum system to remove material from the top of the pit. However, this results in the gradual accumulation of unpumpable sludge at the bottom of the pit, which eventually fills the latrine and forces it to be abandoned. This study has developed a method for fluidising unpumpable pit latrine sludge, based on laboratory experiments using a harmless synthetic sludge. The implications for sludge treatment and disposal are discussed, and the classification of sludges according to the equipment required to remove them from the latrine is proposed. Finally, further work is suggested, including the ongoing development of a device to physically characterise latrine sludge in-situ within the pit.

Surface morphology control of strained InAs/GaAs(331)A films: From nanowires to island-pit pairs

We have studied the effect of molecular beam epitaxy growth conditions on the surface morphology of strained InAs/GaAs(331)A films. Our results reveal that InAs nanowires aligned along the [1 (1) over bar0] direction are formed under As-rich conditions, which is explained by the effect of anisotropic buffer layer surface roughing. Under In-rich conditions, however, the surface morphology of the InAs layers is characterized by a feature of island-pit pairs. In this case, cooperative nucleation of islands and pits can lower the activation barrier for domain growth. These results suggest that the surface morphology of strained InAs layers is highly controllable. (C) 2005 American Institute of Physics.

Identification and functional analysis of a novel bradykinin inhibitory peptide in the venoms of New World Crotalinae pit vipers.

A novel undecapeptide has been isolated and structurally characterized from the venoms of three species of New World pit vipers from the subfamily, Crotalinae. These include the Mexican moccasin (Agkistrodon bilineatus), the prairie rattlesnake (Crotalus viridis viridis), and the South American bushmaster (Lachesis muta). The peptide was purified from all three venoms using a combination of gel permeation chromatography and reverse-phase HPLC. Automated Edman degradation sequencing and MALDI-TOF mass spectrometry established its peptide primary structure as: Thr-Pro-Pro-Ala-Gly-Pro-Asp-Val-Gly-Pro-Arg-OH, with a non-protonated molecular mass of 1063.18 Da. A synthetic replicate of the peptide was found to be an antagonist of bradykinin action at the rat vascular B2 receptor. This is the first bradykinin inhibitory peptide isolated from snake venom. Database searching revealed the peptide to be highly structurally related (10/11 residues) with a domain residing between the bradykinin-potentiating peptide and C-type natriuretic peptide domains of a recently cloned precursor from tropical rattlesnake (Crotalus durissus terrificus) venom gland. BIP thus represents a novel biological entity from snake venom.

The pitfall with PIT tags: Marking freshwater bivalves for translocation induces short-term behavioural costs

Tagging animals is frequently employed in ecological studies to monitor individual behaviour, for example postrelease survival and dispersal of captive-bred animals used in conservation programmes. While the majority of studies focus on the efficacy of tags in facilitating the relocation and identification of individuals, few assess the direct effects of tagging in biasing animal behaviour. We used an experimental approach with a control to differentiate the effects of handling and tagging captive-bred juvenile freshwater pearl mussels, Margaritifera margaritifera, prior to release into the wild. Marking individuals with passive integrated transponder (PIT) tags significantly decreased their burrowing rate and, therefore, increased the time taken to burrow into the substrate. This effect was contributed to, in part, by the detrimental impacts of handling, which also significantly affected activity, burrowing ability and the time taken for each individual to emerge and start probing the substrate. Disturbance during handling and tagging may lead to indirect mortality after release by increasing the risk of predation or dislodgement during flooding, thereby potentially compromising any conservation strategy contingent on population supplementation or reintroduction. This is the first study to demonstrate that handling and PIT tagging has a detrimental impact on invertebrate behaviour. Moreover, our results provide useful information that will inform freshwater bivalve conservation strategies.

Lower corneal hysteresis in glaucoma patients with acquired pit of the optic nerve (APON)

Objective: Acquired pit-like changes of the optic nerve head (APON) are characteristic of glaucomatous damage and may be a sign of a localized susceptibility of the optic nerve. Thus, it is possible that biomechanical properties of the ocular tissues may play a pressure-independent role in the pathogenesis of glaucoma. Corneal hysteresis (CH) appears to provide information of the biomechanical properties of the ocular hull tissues. The purpose of this study was to compare CH of patients with primary open angle glaucoma (POAG) with and without APON. Methods: A prospective case control study was done. POAG patients with and without APON were measured using the Ocular Response Analyzer by masked investigators. Patients in both groups were matched for sex, age, corneal thickness, and type of glaucoma according to maximal IOP (NTG or POAG). Statistical analysis was done using ANOVA. Results: Corneal hysteresis of 16 glaucomatous eyes with APON and 32 controls (glaucoma without APON) was measured. The mean (±SD) CH in the APON group was 8.89 (±1.53) and 10.2 (±1.05) in the control group. The difference is statistically significant (p = 0.005). Conclusions: Corneal hysteresis in POAG patients with APON was significantly lower than in patients that did not have such structural changes of the optic disc. These findings may reflect pressure-independent mechanisms involved in the pathogenesis of such glaucomatous optic nerve changes. © Springer-Verlag 2007.