Water film thickness, flowability and rheology of cement-sand mortar

It is well known that the fresh properties of cement paste and cement-sand mortar are governed mainly by three parameters: water content, packing density and solid surface area. However, these parameters vary simultaneously upon any change in the mix composition and hence the evaluation of their individual and combined effects has been a difficult task. Recently, the authors have found that the effects of these parameters on the flowability and rheological properties of cement paste may be evaluated in terms of the water film thickness (WFT) of the solid-water mixture. Herein, this concept of WFT is extended to cement-sand mortar made of sand with a maximum size of 1.18 mm. A number of mortar samples proportioned with different water contents and different sand gradings were produced for packing density, flowability and rheological properties measurements. From the results, the WFT of each sample was determined and the effects of the WFT on the flowability and rheological properties of the mortar were investigated. The good correlations between the flowability and rheological properties with the WFT revealed that the concept of WFT is applicable also to cement-sand mortar. © 2010 Thomas Telford Ltd.published_or_final_versio

Reducing drying shrinkage of concrete by treatment of aggregate

Drying shrinkage of concrete has been found to cause cracking, water leakage and other serviceability problems and is thus an important research topic. In early studies, it has been found that the shrinkage of concrete varies with the rock aggregate used. This is partly because the aggregate also shrinks and the shrinkage of aggregate is dependent on the type of rock from which the aggregate is derived. However, there have been few studies on the shrinkage of rock and how the shrinkage of aggregate would affect the shrinkage of concrete. In this study, the shrinkage of the granite rock in Hong Kong was measured. It has been found that the rock shrinks quite substantially upon drying and that its shrinkage is dependent on the initial moisture condition. Based on such observation, two alternative methods of treating the aggregate before use so as to reduce the shrinkage of concrete are proposed. Long-term shrinkage measurement of concrete made with untreated and treated aggregates revealed that the proposed methods of aggregate treatment, which are still rudimentary, can significantly reduce the shrinkage of concrete. © 2010 Thomas Telford Ltd.published_or_final_versio

Resumption of sexual activity in patients with myocardial infarction after cardiac rehabilitation

The Medical Research Conference'99, Department of Medicine, The University of Hong Kong, Queen Mary Hospital, Hong Kong, 30-31 January 1999published_or_final_versio

Early responses to H7N9 in southern mainland China

This article is made available through the Brunel Open Access Publishing Fund. © 2014 Goodwin and Sun; licensee BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.Background: H7N9 posed potentially serious health challenges for Chinese society. The previous SARS outbreak in this country was accompanied by contradictory information, while worries about wide-spread influenza led to discrimination worldwide. Early understanding of public threat perceptions is therefore important for effective public health communication and intervention. Methods: We interviewed 1011 respondents by phone two weeks after the first case. Questions examined risk awareness and media use, beliefs about the emergence of the threat and those most at risk, anxiety about infection and preventive and avoidant behaviours. Results: Results demonstrate moderate levels of anxiety but relatively high levels of trust towards government officials. Threat emergence was associated with hygiene levels, temperature change, floating pigs in the Huangpu River and migration to the city. Anxiety predicted both recommended and non-recommended behavioural changes. Conclusions: Comparatively high levels of trust in Chinese government advice about H7N9 contrast positively with previous pandemic communications in China. Anxiety helped drive both recommended and non-recommended behaviours, with potentially important economic and social implications. This included evidence of 'othering’ of those associated with the threat (e.g. migrants). Findings emphasise the need to manage public communications early during new influenza outbreaks.Fudan Tydall Centre and Fudan Media and Public Opinion Center

Territory wide study of patients with dystrophinopathy in Hong Kong

Poster PresentationThis journal issues entitled: 18th International Congress of The World Muscle SocietyThis is a first territory wide study in Hong Kong on Chinese patients with dystrophinopathy on their genetic mutation, motor performance, use of steroid, and the interventions they received. This study is participated by all the paediatric departments in the eleven hospitals in Hong Kong. Clinical data was systemically collected ...postprin

Handwashing practice and the use of personal protective equipment among medical students after the SARS epidemic in Hong Kong

Background: Hand hygiene is an important element of infection control. We conducted 2 surveys on hand hygiene practices and use of personal protective equipment among medical students during and after the outbreak of severe acute respiratory syndrome (SARS) to study its impact on their personal hygiene practice when they contacted patients. Methods: Two cross-sectional surveys were conducted among medical students in their clinical training years (years 3-5) in a teaching hospital (at which the first and major SARS outbreak occurred) in March 2003 and August 2004, respectively. Results: Prior to the recognition of the SARS outbreak in March 2003, 35.2% of the students washed their hands before and 72.5% after they physically examined patients in the wards. None of the students wore masks during history taking and physical examination. In the 2004 survey, the corresponding proportions were 60.3% and 100%, respectively, and 86.1% and 93.8% of students wore masks during history taking and physical examination, respectively. Attitudes to handwashing and perception of infection risk were not significantly associated with handwashing practice, whereas peer behavior might be a significant influencing factor. Conclusion: A significant improvement in compliance with hand hygiene practice was found after the SARS outbreak. Copyright © 2005 by the Association for Professionals in Infection Control and Epidemiology, Inc.link_to_subscribed_fulltex

A review of the evidence for hand hygiene in different clinical and community settings for family physicians

This paper discusses the evidence of hand hygiene (mainly hygienic hand antisepsis) in reducing infections in different settings. In the hospital setting, there is convincing evidence that hand hygiene is effective in reducing nosocomial infections such as urinary tract infection, pneumonia, surgical wound infection and sepsis of in-patients, and in reducing the incidence rates of infection with methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant enterococci (VRE). In long-term care facilities, there is limited evidence to prove whether hand hygiene is effective or not in reducing infections. In institutions such as schools, it is evident that hand hygiene is effective in reducing gastrointestinal illnesses and probably respiratory illnesses among healthy children and young adults. In the community, it is evident that hand hygiene is effective in reducing diarrhoea among healthy individuals within families. Unfortunately, despite the above evidence, doctors are constantly reported to have poor compliance in many studies. Therefore it is important for doctors to improve their compliance in hand hygiene whether they practise in hospitals or in their own clinics.link_to_subscribed_fulltex

Wet packing of crushed rock fine aggregate

It is well known that the performance of concrete is dependent on the packing density of the aggregate. All existing methods of measuring the packing density of aggregate are carried out under dry condition. However, these dry packing methods are sensitive to the amount of compaction applied and do not account for the effect of water in the concrete mix. In this research, a new method, which measures the packing density of aggregate under wet condition, has been developed. It is called the wet packing method and has the advantages that it is less sensitive to the amount of compaction applied and that it includes the effect of water. The wet packing method was compared to the dry packing method by applying both methods to measure the packing density of crushed rock fine aggregate. It was found that the packing density of crushed rock fine aggregate can be 24% higher under wet condition than under dry condition and that the addition of superplasticizer can have a marginal contributing effect. Furthermore, it was demonstrated that the beneficial effect of blending different size aggregates together is better revealed by the wet packing method than by the dry packing method. © 2008 RILEM.link_to_subscribed_fulltex