Low Friction Flows of Liquids at Nanopatterned Interfaces

With the recent important development of microfluidic systems, miniaturization of flow devices has become a real challenge. Microchannels, however, are characterized by a large surface to volume ratio, so that surface properties strongly affect flow resistance in submicrometric devices. We present here results showing that the concerted effect of wetting . properties and surface roughness may considerably reduce friction of the fluid past the boundaries. The slippage of the fluid at the channel boundaries is shown to be drastically increased by using surfaces that are patterned at the nanometer scale. This effect occurs in the regime where the surface pattern is partially dewetted, in the spirit of the 'superhydrophobic' effects that have been recently discovered at the macroscopic scales. Our results show for the first time that, in contrast to the common belief, surface friction may be reduced by surface roughness. They also open the possibility of a controlled realization of the 'nanobubbles' that have long been suspected to play a role in interfacial slippag

Search for gravitational waves associated with gamma-ray bursts detected by Fermi and Swift during the LIGO–Virgo run O3b

We search for gravitational-wave signals associated with gamma-ray bursts (GRBs) detected by the Fermi and Swift satellites during the second half of the third observing run of Advanced LIGO and Advanced Virgo (2019 November 1 15:00 UTC–2020 March 27 17:00 UTC). We conduct two independent searches: a generic gravitational-wave transients search to analyze 86 GRBs and an analysis to target binary mergers with at least one neutron star as short GRB progenitors for 17 events. We find no significant evidence for gravitational-wave signals associated with any of these GRBs. A weighted binomial test of the combined results finds no evidence for subthreshold gravitational-wave signals associated with this GRB ensemble either. We use several source types and signal morphologies during the searches, resulting in lower bounds on the estimated distance to each GRB. Finally, we constrain the population of low-luminosity short GRBs using results from the first to the third observing runs of Advanced LIGO and Advanced Virgo. The resulting population is in accordance with the local binary neutron star merger rate

A questionnaire survey of endodontic practice profile among dentists in Hong Kong

Objectives. The present study aimed to gather information on the prevailing endodontic practice of general dental practitioners in Hong Kong. Methods. A cross-sectional postal survey was conducted on 1167 members of the Hong Kong Dental Association in 2001. Information about the materials and techniques used in endodontic treatment was collected. Results. A total of 369 replies were received, of which 343 with valid responses were analyzed, which accounted for 29% of the population surveyed. About half of the respondents (56%) performed one to five endodontic treatments weekly. Over one quarter (28%) routinely used a rubber dam in endodontic treatment. A wide variety of instruments were used for root canal preparation; stainless steel hand files being the most popular (89%). Rotary nickel-titanium instrumentation was practiced by 21% of respondents. Sodium hypochlorite irrigation and calcium hydroxide dressings were used by 63% and 43% of respondents, respectively. Most general dental practitioners (87%) obturated root canals with lateral compaction of gutta-percha. Single-visit treatment was not common; less than 20% of respondents practiced it to a limited extent. Conclusion. Within the limits and the low response rate to the present survey, the results suggest that Hong Kong general dental practitioners treat root canals using techniques and materials commonly taught in dental schools, often as multiple-visit treatments. The utilization of rubber dams in root canal treatment remains low

Reliability and validity of the euthanasia attitude scale (EAS) for Hong Kong medical doctors

This study aimed to examine the reliability and validity of the Euthanasia Attitude Scale (EAS) in Hong Kong medical doctors. A total of 107 medical doctors (61.7% men) participated in a survey at clinical settings in 2008. The 21-item EAS was used to assess their attitudes toward euthanasia. The mean (standard deviation) and median of the EAS were 63.60 (60.31) and 63.00. Total EAS scores correlated well with "Ethical Considerations," "Practical Considerations," and "Treasuring Life" (Spearman ρ =.37-.96, P <.001) but not "Naturalistic Beliefs." The construct validity of the 3-factor model was appropriate (Kaiser-Meyer-Olkin [KMO] value = 0.90) and showed high internal consistency (Cronbach α =.79-.92). Euthanasia Attitude Scale may be a reliable and valid measure for assessing the attitudes toward euthanasia in medical professionals. © The Author(s) 2010.link_to_subscribed_fulltex

An integrated approach for water minimisation in a PVC manufacturing process

This paper presents a water minimisation study carried out for a polyvinyl chloride (PVC) resins manufacturing plant. Due to the complexity of the mixed batch and continuous polymerisation process, an integrated process integration approach, which consists of process synthesis, analysis and optimisation was used for this work. A simulation model was first developed in a batch process simulation software, SuperPro Designer V6.0, based on the operating condition of a PVC manufacturing process. The batch simulation model captured the essential information needed for a water minimisation study, e.g. process duration, water mass flow, etc. Data extracted from the simulation model was later used in the water minimisation study, utilising the widely established process synthesis technique of water pinch analysis. Two water saving scenarios were presented. Scenario 1 reports a fresh water and wastewater reduction of 28.5 and 90.1% respectively, for the maximum water recovery scheme without water storage system. In Scenario 2, higher fresh water and wastewater reduction are reported at 31.7 and 100% respectively, when water storage tank is installed in the water network

False-positive SARS-CoV-2 serology in 3 children with Kawasaki disease

BACKGROUND: Kawasaki disease (KD) is an acute febrile and eruptive disease with systemic vasculitis predominantly affecting young East Asian children. Recent reports showed that children with KD-like disease from KD low prevalence regions had positive SARS-CoV-2 serology despite a negative SARS-CoV-2 polymerase chain reaction (PCR) in respiratory samples. OBJECTIVES: To describe 3 pediatric Kawasaki Disease patients with false positive SARS-CoV-2 serology. STUDY DESIGN: We retrospectively recruited children with KD diagnosed during the COVID-19 outbreak in Hong Kong. Clinical characteristics and laboratory test results including SARS-CoV-2 PCR results were retrieved. We performed a microparticle-based immunoassay for the detection of IgG against nucleoprotein (NP) and spike protein receptor binding domain (RBD), and a microneutralization assay for the detection of neutralizing antibodies. RESULTS: Three Chinese children with typical KD were identified. They had no epidemiological links with COVID-19 patients and tested negative for SARS-CoV-2 NPA PCR. They were treated with IVIG and aspirin, and were discharged without complications. Subsequently 2 of them were tested positive against anti-RBD and anti-NP antibodies and 1 was tested positive against anti- RBD antibodies. However, microneutralization assay showed that neutralizing antibodies were absent, suggesting a false-positive IgG result. CONCLUSION: Detection of neutralizing antibodies is recommended to confirm previous SARS-CoV-2 infection in IgG-positive but PCR-negative patients

Prognostic value of medulloblastoma extent of resection after accounting for molecular subgroup: a retrospective integrated clinical and molecular analysis

Background Patients with incomplete surgical resection of medulloblastoma are controversially regarded as having a marker of high-risk disease, which leads to patients undergoing aggressive surgical resections, so-called second-look surgeries, and intensified chemoradiotherapy. All previous studies assessing the clinical importance of extent of resection have not accounted for molecular subgroup. We analysed the prognostic value of extent of resection in a subgroup-specific manner. Methods We retrospectively identified patients who had a histological diagnosis of medulloblastoma and complete data about extent of resection and survival from centres participating in the Medulloblastoma Advanced Genomics International Consortium. We collected from resections done between April, 1997, and February, 2013, at 35 international institutions. We established medulloblastoma subgroup affiliation by gene expression profiling on frozen or formalin-fixed paraffin-embedded tissues. We classified extent of resection on the basis of postoperative imaging as gross total resection (no residual tumour), near-total resection (= 1.5 cm(2) tumour remaining). We did multivariable analyses of overall survival and progression-free survival using the variables molecular subgroup (WNT, SHH, group 4, and group 3), age (= 3 years old), metastatic status (metastases vs no metastases), geographical location of therapy (North America/Australia vs rest of the world), receipt of chemotherapy (yes vs no) and receipt of craniospinal irradiation ( 30 Gy vs no craniospinal irradiation). The primary analysis outcome was the effect of extent of resection by molecular subgroup and the effects of other clinical variables on overall and progression-free survival. Findings We included 787 patients with medulloblastoma (86 with WNT tumours, 242 with SHH tumours, 163 with group 3 tumours, and 296 with group 4 tumours) in our multivariable Cox models of progression-free and overall survival. We found that the prognostic benefit of increased extent of resection for patients with medulloblastoma is attenuated after molecular subgroup affiliation is taken into account. We identified a progression-free survival benefit for gross total resection over sub-total resection (hazard ratio [HR] 1.45, 95% CI 1.07-1.96, p=0.16) but no overall survival benefit (HR 1.23, 0.87-1.72, p=0.24). We saw no progression-free survival or overall survival benefit for gross total resection compared with near-total resection (HR 1.05, 0.71-1.53, p=0.8158 for progression-free survival and HR 1.14, 0.75-1.72, p=0.55 for overall survival). No significant survival benefit existed for greater extent of resection for patients with WNT, SHH, or group 3 tumours (HR 1.03, 0.67-1.58, p=0.89 for sub-total resection vs gross total resection). For patients with group 4 tumours, gross total resection conferred a benefit to progression-free survival compared with sub-total resection (HR 1.97, 1.22-3.17, p= 0.0056), especially for those with metastatic disease (HR 2.22, 1.00-4.93, p= 0.050). However, gross total resection had no effect on overall survival compared with sub-total resection in patients with group 4 tumours (HR 1.67, 0.93-2.99, p= 0.084). Interpretation The prognostic benefit of increased extent of resection for patients with medulloblastoma is attenuated after molecular subgroup affiliation is taken into account. Although maximum safe surgical resection should remain the standard of care, surgical removal of small residual portions of medulloblastoma is not recommended when the likelihood of neurological morbidity is high because there is no definitive benefit to gross total resection compared with near-total resection