Critical flux in ultrafiltration of skimmed milk

he best operating conditions, using the critical flux concept during ultrafiltration of skimmed milk, were evaluated for tubular membranes. It was found that irreversible fouling was greatly reduced by operating at or below the critical flux, but was not totally eliminated. The critical flux of skimmed milk was found to be the weak form. The critical flux at cross flow velocity 3.4 in s(-1) for MWCO 200 kDa membrane was 56.9 kg m(-2) h(-1) while for MWCO 25 kDa membranes it was 45 kg m(2) h(-1) suggesting that membrane pore size influenced the flux. The critical flux increased with increasing wall shear stress and decreased with increasing protein concentration. Empirical equations, for predicting the critical flux (J(crit)) for skimmed milk with a protein concentration (c(b)) in the range 3-7% w/w and wall shear stress (tau(w)) in the range 7-60 Pa for MWCO 200 kDa and 25 kDa membranes were J(crit) = 5.1 (tau(w)/c(b)) and J(crit) = 4.0 (tau(w)/c(b)) respectively. In general, the rejections of protein and lactose at the critical flux were not affected by protein concentration, wall shear stress and membrane used, and they were similar to those found when operating at the limiting flux.

Conjugated linoleic acid and human health: a critical evaluation of the evidence

Purpose of review: This review critically evaluates studies investigating the effects of conjugated linoleic acid on human health, including effects on body composition, blood lipids, liver metabolism, insulin sensitivity and immune function. It focuses mainly on human intervention studies, but includes some reference to animal and cellular studies which provide insight into potential molecular mechanisms of action of conjugated linoleic acid. Recent findings: Human studies continue to report inconsistent effects of conjugated linoleic acid on human health. Some of these reports are based on overinterpretation of marginal effects of supplementation. Recent data suggest that the effects of the substance may be isomer dependent and that cis-9, trans-11 and trans-10, cis-12 conjugated linoleic acids have opposing effects on blood lipids and on metabolism in adipocytes and hepatic cells. Summary: Claims that conjugated linoleic acid is beneficial for health remain as yet unconvincing. Human studies investigating the effects of conjugated linoleic acid supplements have tended to use mixtures of isomers and have been inconsistent. More recent studies have attempted to use relatively pure preparations of single isomers and these studies suggest that the effects of conjugated linoleic acid may be isomer-specific. These recent data suggest a relative detrimental effect of trans-10, cis-12 conjugated linoleic acid on blood lipids. There appears to be little effect of conjugated linoleic acid on immune function and the effects on insulin sensitivity remain unclear.

Critical stages of the brewing process for changes in antioxidant activity and levels of phenolic compounds in ale

Samples were taken at each stage of brewing (malt, milling, mashing, wort separation, hop addition, boiling, whirlpool, dilution, fermentation, warm rest, chill-lagering, beer filtration, carbonation and bottling, pasteurization, and storage). The level of antioxidant activity of unfractionated, low-molecular-mass (LMM) and high-molecular-mass (HMM) fractions was measured by the 2,2'-azinobis(3-ethylbenzothiazoline-6-sulfortic acid) radical cation (ABTS(.+)) and ferric-reducing antioxidant power (FRAP) procedures. Polyphenol levels were assessed by HPLC. The LMM fraction (<5 kDa) was responsible for similar to80% of the level of antioxidant activity of the unfractionated malt and beer samples. In the unfractionated samples, significant decreases (P < 0.001) in antioxidant activity levels were observed after milling and beer filtration, with the decrease after beer filtration being accompanied by a significant decrease (P > 0.001) in catechin and ferulic acid levels. Increases in antioxidant activity levels were observed after mashing, boiling, fermentation, chill-lagering, and pasteurization, in line with previous studies on lager. Additionally, increases in the level of antioxidant activity occurred after wort separation and carbonation and bottling and were accompanied by increases in levels of most monitored polyphenols. Data from the ABTS(.-) and FRAP assays indicated that the compounds contributing to the levels of antioxidant activity responded differently in the two procedures. Levels of ferulic, vanillic, and chlorogenic acids and catechin accounted for 45-61% of the variation in antioxidant activity levels.

Critical review of health effects of soyabean phyto-oestrogens in post-menopausal women

A consensus view of soyabean phyto-oestrogens in clinical interventions in post-menopausal women is presented that is based on data from the EU-funded project Phytohealth. The phyto-oestrogens, primarily genistein and daidzein, were given as soyabean-protein isolates, whole-soyabean foods or extracts, supplements or pure compounds. A comprehensive literature search was conducted with well-defined inclusion or exclusion criteria. For areas for which substantial research exists only placebo-controlled double-blind randomised controlled trials (RCT) conducted on healthy post-menopausal women were included. For emerging areas all available human studies in post-menopausal women were reviewed. In order to make cross comparisons between studies the doses of isoflavones were calculated as aglycone equivalents. There is a suggestion, but no conclusive evidence, that isoflavones from the sources studied so far have a beneficial effect on bone health. The consumption of whole-soyabean foods and soyabean-protein isolates has some beneficial effects on lipid markers of cardiovascular risk. The consumption of isolated isoflavones does not affect blood lipid levels or blood pressure, although it may improve endothelial function. For menopausal symptoms there is currently limited evidence that soyabean-protein isolates, soyabean foods or red-clover (Trifolium pratense L.) extract are effective but soyabean isoflavone extracts may be effective in reducing hot flushes. There are too few RCT studies to reach conclusions on the effects of isoflavones on breast cancer, colon cancer, diabetes or cognitive function. The health benefits of soyabean phyto-oestrogens in healthy post-menopausal women are subtle and even some well-designed studies do not show protective effects. Future studies should focus on high-risk post-menopausal women, especially in the areas of diabetes, CVD, breast cancer and bone health.

Critical notices: subjective, intersubjective, objective

Book review of 'Subjective, intersubjective, objective' by Donald Davidson.

Critical studies: aspects of reason I

Book review of 'Aspects of reason' by P. Grice.

Knowledge transfer processes in PFI/PPP: critical success factors

Successful knowledge transfer is an important process which requires continuous improvement in today’s knowledge-intensive economy. However, improving knowledge transfer processes represents a challenge for construction practitioners due to the complexity of knowledge acquisition, codification and sharing. Although knowledge transfer is context based, understanding the critical success factors can lead to improvements in the transfer process. This paper seeks to identify and evaluate the most significant critical factors for improving knowledge transfer processes in Public Private Partnerships/Private Finance Initiatives (PPP/PFI) projects. Drawing upon a questionnaire survey of 52 construction firms located in the UK, data is analysed using Severity Index (SI) and Coefficient of Variation (COV), to examine and identify these factors in PPP/PFI schemes. The findings suggest that a supportive leadership, participation/commitment from the relevant parties, and good communication between the relevant parties are crucial to improving knowledge transfer processes in PFI schemes. Practitioners, managers and researchers can use the findings to efficiently design performance measures for analysing and improving knowledge transfer processes.

Critical Mass: Sermon for the Church of the Atom (part of A Theatre to Address at Arnolfini, Bristol and Late at Tate Britain)

A Theatre to Address explores the work of contemporary artists who use text as both a visual and sonic form. In this programme, text appears not primarily as a means of communication, but as something which has shape and structure of its own. The Reading Room will also be displaying work that looks at text as concrete or visual poetry, and the script in artists' practice. Clare Gasson presents a new work The traveller - walking walking walking through ... that explores the connection between the text, the rhythm and the action. Maryam Jafri presents a performance-lecture Death With Friends, a body of visual and textual material that forms the basis for her new film of the same name. Pil and Galia Kollectiv present a radical worship for the apocalypse, featuring a sermon for the Church of the Atom with live music by Gelbart.