Influence of freezing method on thaw drip and protein loss of low-voltage electrically stimulated and non-stimulated sheeps' muscle

South African Mutton Merino wethers (n = 32) were slaughtered, yielding carcasses with a mean weight of 22·18 ± 2·11 kg. Sixteen carcasses were electrically stimulated (ES) (21 V, 60 Hz, 120 s) immediately and all carcasses were chilled at room temperature (16°C) for 3 h and then overnight at 4°C, 95% RH. Both left and right Mm. longissimus lumborum et thoracis were excised and cut into six portions (77 g ± 7·8 g), each placed separately in a polyethylene bag and randomly allocated to five freezing treatments. These were: (1) cryogenic, -65°C; (2) cryogenic, -90°C; (3) walk-in-freezer, -21°C; (4) blast freezer, -21°C; (5) domestic freezer, -25°C. The respective freezing rates were 4·4, 6·4, 0·55, 0·35 and 0·51 cm h(-1) to -2·2°C at core depth of 1 cm below the surface. Samples were frozen to core temperatures of -20°C, removed and placed in a storage freezer (-20°C) for 48 h and 2·5 months. Samples were then suspended in perforated bags in a chiller (4°C) to thaw, and drip was collected in outer bags over the periods 0-24, 24-48, 48-72 and 72-96 h and expressed as g (100 g)(-1). Freezing methods had significant (P < 0·01) influences on drip loss in both ES and NES samples. Following storage for 48 h post-freezing at -20°C, total drip (g (100 g)(-1)) over 96 h of both ES and NES samples for the five freezing treatments were respectively: (1) 7·61 and 4·61; (2) 7·35 and 3·29; (3) 9·44 and 4·68; (4) 9·07 and 5·43; (5) 10·58 and 5·15. Following storage for 2·5 months, the total ES and NES drip were respectively, (1) 11·25 and 9·38; (2) 10·36 and 9·15; (3) 13·72 and 12·65; (4) 13·70 and 12·26; (5) 11·92 and 11·29. Total protein in the drip did not differ between freezing treatments. Differences between ES and NES samples did occur in the 48 h storage group. It is concluded that cryogenic freezing results in less thaw drip than the vapour compression systems. This advantage of cryogenic freezing disappears if meat is stored for long periods at -20°C. Electrical stimulation increases the drip loss in samples frozen for 48 h, but the differences are not significant after 2·5 months frozen storage. Protein losses parallel the drip.     

Replica Management in the European DataGrid Project

Within the European DataGrid project, Work Package 2 has designed and implemented a set of integrated replica management services for use by data intensive scientific applications. These services, based on the web services model, enable movement and replication of data at high speed from one geographical site to another, management of distributed replicated data, optimization of access to data, and the provision of a metadata management tool. In this paper we describe the architecture and implementation of these services and evaluate their performance under demanding Grid conditions.This work was partially funded by the European Commission program IST- 2000-25182 through the European DataGrid Project.     

Comparison of the square-wave and quasi-resonant topologies

The waveforms of a square-wave DC-DC converter and a quasiresonant DC-DC converter are examined in detail and a comparison is made between the switching losses and conduction losses for each topology. Using data from commercially available semiconductor devices, conservative estimates are then given for the switching frequency at which the resonant approach becomes advantageous. The effect of an isolation transformer on this comparison is also addressed     

Butyltin compounds in retail mollusc products

Butyltin was found in 62 of 74 mollusc products purchased from major supermarket outlets in seven cities across Canada. Tribuyltin was detected in 41 samples, with levels up to 233 ng g^-1. Dibutyltin and monobutyltin levels ranged up to 88 and 53 ng g^-1, respectively. Products originating from East and South East Asia generally contained the highest levels. Gastropods contained lower levels than other molluscs. Enzymatically hydrolysed samples were extracted with 0.05% tropolone in hexane-diethyl ether (1 : 1). Ethyl derivatives were made by Grignard reaction and analysed by gas chromatography coupled to an atomic emission detector. Gas chromatograph-mass spectrometry confirmed the presence of butyltins in the mollusc samples.     

Fan pressurization uses for fire protection

Today's fire protection community is witnessing the coming-of-age of fan pressurization technology, which is currently providing much-needed support in the struggle to approve and maintain applications involving fire protection halons. Yet the advantages of this technology go far beyond halon applications. Fan pressurization techniques provide an effective tool for handling some of the most fundamental fire protection concepts.     

Estrogen affects development of alveolar structures in whole-organ culture of mouse mammary glands

Many in vitro studies show estrogen regulation of the hypothalamic pro-opiomelanocortin (POMC) system, including a decrease in hypothalamic POMC mRNA after estradiol treatment. Because such in vivo experiments do not allow one to determine whether peripheral, interacting systems or extra-hypothalamic brain regions are involved in this regulation, we sought to establish whether estrogen acts directly in hypothalamus to decrease POMC mRNA. Using an in vitro approach, we studied effects of estradiol (E2) on POMC/cyclophilin mRNA concentrations (RNAse protection assays) in neuronal cultures derived from day 17 fetal rat hypothalamus. Chemically defined medium was deprived of progesterone for 2 days prior to E2 treatment and for the duration of the study. E2 (10(-13)-10(-9) M) dose-dependently decreased POMC mRNA concentrations during a 2-day treatment. Whereas the lowest dose (10(-13) M) of E2 resulted in a statistically significant 44% decrease in POMC mRNA concentrations relative to control cultures, this inhibitory effect was lost because higher doses (10(-11) and 10(-9) M) did not produce statistically significant decrements (22 and 16%, respectively) in POMC mRNA concentrations. Additional time course studies revealed that this decrease in POMC mRNA can be seen as early as 4 h after E2 (10(-13) M) treatment. We conclude that E2 inhibition of POMC mRNA concentrations in hypothalamic neuronal cultures indicates that this inhibition can occur directly in hypothalamus.