Wind flow in the recessed cavities of a tall building

Fulltext in: http://www.iawe.org/Proceedings/7APCWE/M3D_3.pdfTechnical Session: M3-D Computational Wind Engineering (2), no.3In a congested city like Hong Kong, residential tall buildings are often built with an irregular plan form and with a number of apartments arranged as wing sections extending from a central core. To provide views and sufficient ventilation to the apartments, deeply recessed cavities are placed between adjacent building wings. This paper reports a CFD study of the wind-induced flow inside a recessed cavity of a tall building with an objective to assess the adequacy of ventilation inside the cavity. The dimensions of the cavity are varied systematically to investigate the flow exchange between the cavity and the outside at different heights. It is found that the flow inside the cavity is not a simple cross flow or a stagnation flow. Flow exchange takes place in different directions along the building heights.link_to_subscribed_fulltex

Venous thromboembolism in the Chinese population - Experience in a regional hospital in Hong Kong

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Common association of haemolytic uraemic syndrome with invasive Streptococcus pneumoniae infection in five Chinese paediatric patients

Haemolytic uraemic syndrome is an important cause of acute renal impairment in childhood. We review the incidence, and clinical and laboratory features of haemolytic uraemic syndrome in a Chinese population. Five patients were identified from 2006 to 2008. All patients were young children with associated invasive Streptococcus pneumoniae pulmonary infection. Serotypes 3, 14, and 19A were confirmed in four patients. The classical post-diarrhoeal form associated with Escherichia coli (O157:H7) infection was not seen. One patient died of acute respiratory failure. Streptococcus pneumoniae infection, as an associated condition in haemolytic uraemic syndrome, is important and relatively common in Chinese patients, especially among children. The acute clinical picture is similar to that reported in the western literature, except for an uncommon association with meningitis. The medium-term renal outcome of the Chinese population appears to be more favourable than the Caucasians. Widespread vaccination against Streptococcus pneumoniae may have resulted in changes in bacterial epidemiology and clinicians should be continuously aware of this severe disease. The use of washed blood components for transfusion in the acute stage requires further study.published_or_final_versio

Omicron variant susceptibility to neutralizing antibodies induced in children by natural SARS-CoV-2 infection or COVID-19 vaccine

The novel SARS-CoV-2 Omicron variant may increase the risk of re-infection and vaccine breakthrough infections as it possesses key mutations in the spike protein that affect neutralizing antibody response. Most studies on neutralization susceptibility were conducted using specimens from adult COVID-19 patients or vaccine recipients. However, since the paediatric population has an antibody response to SARS-CoV-2 infection that is distinct from the adult population, it is critical to assess the neutralization susceptibility of pediatric serum specimens. This study compared the neutralization susceptibility of serum specimens collected from 49 individuals of <18 years old, including 34 adolescent BNT162b2 (Pfizer-BioNTech) vaccine recipients, and 15 recovered COVID-19 patients aged between 2 and 17. We demonstrated that only 38.2% of BNT162b2 vaccine recipients and 26.7% of recovered COVID-19 patients had their serum neutralization titre at or above the detection threshold in our live virus microneutralization assay. Furthermore, the neutralizing antibody titer against the Omicron variant was substantially lower than those against the ancestral virus or the Beta variant. Our results suggest that vaccine recipients and COVID-19 patients in the pediatric age group will likely be more susceptible to vaccine breakthrough infections or reinfections due to the Omicron variant than previous variants

Indwelling catheter-related central venous thrombosis during bone marrow transplantation [10]

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A CFD study of Hong Kong refuge floor design: floor height effect

Since 1996, the provision of a refuge floor has been a mandatory feature for all new tall buildings in Hong Kong. These floors are designed to provide for the building occupants a fire safe environment that is also free from smoke. However, the desired cross ventilation on these floors to achieve the removal of smoke, assumed by the Building Codes of Hong Kong, is still being questioned so that a further scientific study of the wind-induced ventilation of a refuge floor is needed. This paper presents an investigation into this issue. The developed computational technique used in this paper was adopted to study the wind-induced natural ventilation on a refuge floor. The aim of the investigation was to establish whether a refuge floor with a central core and having cross ventilation produced by only two open opposite external side walls on the refuge floor would provide the required protection in all situations taking into account behaviour of wind due to different floor heights, wall boundary conditions and turbulence intensity profiles. The results revealed that natural ventilation can be increased by increasing the floor height provided the wind angle to the building is less than 90°. The effectiveness of the solution was greatly reduced when the wind was blowing at 90° to the refuge floor opening.link_to_subscribed_fulltex

Invasive Streptococcus pneumoniae infection associated with hemolytic uremic syndrome in Chinese pediatric patients

Hemolytic uremic syndrome (HUS) associated with pneumococcal pneumonia is rarely reported in the Western literature, in contrast to classical HUS associated with Escherichia coli (E. coli) (O157:H7). We conducted a retrospective review over a 2-year period from 2006 to 2008 in a large tertiary teaching hospital. Five cases were identified. All patients were Chinese children with a median age of 3 years (range: 2 – 4 years). No documented case of E. coli (O157:H7) infection was seen in the same hospital over the past 5 years from 2003 to 2008. Streptococcus pneumoniae (S. pneumoniae) infection was confirmed by positive blood and/or pleural fluid culture. Four of 5 patients developed empyema requiring decortication. HUS was diagnosed as early as 3 days after onset of febrile illness and was apparent within 2 weeks in all patients. The mean nadir for hemoglobin and platelet was 41 g/L (range: 13 – 55 g/L) and 7 ×109/L (range: 4 – 9 ×109/L), respectively. None of them had significant bleeding. All patients received red cell transfusion and 4 of 5 patients received platelet transfusion for prophylaxis or for coverage of invasive procedures. T activation on red cells was documented in all cases. Washed red cells and concentrated pooled platelet-rich plasma were transfused, except for 1 case when transfusion took place before a diagnosis of HUS was made. All patients had impaired renal function as evident by a raised serum creatinine level (range: 101– 756 umol/L). Only 1 patient required dialysis. One patient deteriorated rapidly and died of refractory septicemic shock and multi-organ failure 30 hours after admission. Her hemoglobin and platelet on admission was 106 g/L and 115 ×109/L, respectively. She received unwashed red cells and ordinary platelet concentrate upon clinical deterioration. Blood smear examination and T activation study subsequently confirmed a diagnosis of S. pneumoniae associated HUS. All surviving patients had full renal and hematological recovery with a median follow up of 11 months (range: 3 – 28 months). Invasive S. pneumoniae infection is a relatively common association in Chinese pediatric patients with HUS. This condition can be fatal in the acute state but the medium to long term prognosis is favorable. Transfusion of washed red cells and plasma-reduced platelets is a routine practice in this group of patients, although the efficacy and necessity of this practice has not been formally studied. © 2008, The American Society of Hematolog

Carbon fibre-organoclay hybrid epoxy composites: Fracture behaviours and mechanical properties

The fracture resistance and mechanical properties of carbon fiber reinforced composites (CFRPs) containing organoclay-filled epoxy resin are studied. The XRD analysis and TEM examination revealed well-dispersed organoclay in the epoxy matrix displaying a mixture of exfoliation and intercalation. There was a significant improvement in flexural modulus and a marginal reduction in flexural strength of epoxy matrix due to the incorporation of organoclay. The quasi-static fracture toughness of epoxy increased nearly 60\% with the addition of 3wt\% clay, but there was a 45\% drop in impact fracture toughness with 1wt\% clay. When CFRPs were fabricated with the clay-modified epoxy resin, both the flexural modulus and strength of the hybrid composites showed negligible changes due to a few wt\% of organoclay in the matrix. The interlaminar crack growth stability and the corresponding mode I interlaminar fracture toughness of the hybrid composites with organoclay improved substantially compared to those with carbon fibres only. The hybrid composites typically presented rough matrix surface associated with pinning and crack tip bifurcation, whereas the composite made from neat epoxy showed a smooth river line structure which is characteristic of brittle epoxy. The correlation between the composite interlaminar fracture properties and the toughness of modified matrix is discussed

Invasive Streptococcus pneumoniae infection associated with hemolytic uremic syndrome in Chinese pediatric patients

Hemolytic uremic syndrome (HUS) associated with pneumococcal pneumonia is rarely reported in the Western literature, in contrast to classical HUS associated with Escherichia coli (E. coli) (O157:H7). We conducted a retrospective review over a 2-year period from 2006 to 2008 in a large tertiary teaching hospital. Five cases were identified. All patients were Chinese children with a median age of 3 years (range: 2 – 4 years). No documented case of E. coli (O157:H7) infection was seen in the same hospital over the past 5 years from 2003 to 2008. Streptococcus pneumoniae (S. pneumoniae) infection was confirmed by positive blood and/or pleural fluid culture. Four of 5 patients developed empyema requiring decortication. HUS was diagnosed as early as 3 days after onset of febrile illness and was apparent within 2 weeks in all patients. The mean nadir for hemoglobin and platelet was 41 g/L (range: 13 – 55 g/L) and 7 ×109/L (range: 4 – 9 ×109/L), respectively. None of them had significant bleeding. All patients received red cell transfusion and 4 of 5 patients received platelet transfusion for prophylaxis or for coverage of invasive procedures. T activation on red cells was documented in all cases. Washed red cells and concentrated pooled platelet-rich plasma were transfused, except for 1 case when transfusion took place before a diagnosis of HUS was made. All patients had impaired renal function as evident by a raised serum creatinine level (range: 101– 756 umol/L). Only 1 patient required dialysis. One patient deteriorated rapidly and died of refractory septicemic shock and multi-organ failure 30 hours after admission. Her hemoglobin and platelet on admission was 106 g/L and 115 ×109/L, respectively. She received unwashed red cells and ordinary platelet concentrate upon clinical deterioration. Blood smear examination and T activation study subsequently confirmed a diagnosis of S. pneumoniae associated HUS. All surviving patients had full renal and hematological recovery with a median follow up of 11 months (range: 3 – 28 months). Invasive S. pneumoniae infection is a relatively common association in Chinese pediatric patients with HUS. This condition can be fatal in the acute state but the medium to long term prognosis is favorable. Transfusion of washed red cells and plasma-reduced platelets is a routine practice in this group of patients, although the efficacy and necessity of this practice has not been formally studied. © 2008, The American Society of Hematolog