Nano silica dispersion in epoxy: the investigation of heat, milling speed and duration effect

Nano composites are a promising development but the challenge of homogenous and discrete dispersion of the nano fillers are barriers that must be overcome before they can be effectively implemented. Although the common dispersion methods such as particle surface modification, comprehensive milling metrologies and the usage of solvents bear results, these are time consuming and not cost effective. In this paper, we explore the efficiency of coupling the usage of ball-media and heat on the dispersion of nano silica in epoxy. No solvents are involved. The effects of milling speed and duration are also studied albeit under a fixed ball media : silica-epoxy volume ratio of 3:5. The experiment set-up involves a simple 3-blade mixer, round bottom flask and 60 ? m zirconia ball. At nano silica loading of 10 wt % the nano silica clusters are systematically reduced from 1.5 - 2 ? m to 100 - 200 nm with the usage of ball media and application of heat. At the optimum milling speed and duration of 500 rpm for 5 hours, the aggregate sizes were further reduced to 30 - 70 nm, which is almost a discrete dispersion

Carbon Nanotube-Modified MnO2: An Efficient Electrocatalyst for Oxygen Reduction Reaction

In this work, manganese dioxide/carbon nanotube (MnO2/CNT) have been synthesized by sonochemical-coprecipitation method and demonstrated that it could be an effective electrocatalyst for oxygen reduction reaction (ORR). Moreover, the effect of CNT inclusion with MnO2 was also investigated for ORR. The physical and electrochemical properties of the MnO2/CNT were examined by powder X-ray diffraction (XRD), Fourier Transform Infrared (FT-IR) spectroscopy, Brunauer-Emmett-Teller (BET), Transmission Electron Microscopy (TEM), Field Emission Scanning Electron Microscopy/Energy Dispersive X-ray (FESEM/EDX), Cyclic Voltammetry (CV), Electrochemical Impedance Spectroscopy (EIS), Mott-Schottky and Rotating Disk Electrode (RDE) analysis. CV showed higher currents for the ORR in MnO2/CNT than CNT; however, ORR current dropped when the MnO2 loading was increased from 20–40 %. The EIS analysis showed that charge-transfer resistance for MnO2/CNT was significantly lower compared to the MnO2 indicating that MnO2 has good contact with CNT and the composite possess high electrical conductivity. Mott-Schottky results demonstrated that incorporation of CNT into MnO2 resulted in producing larger electron density in n-type MnO2/CNT compared to MnO2 which is liable for efficient electron donation from the Mn3+ to adsorbed oxygen in the rate determining step. RDE results showed that MnO2/CNT follows 4e− transfer pathway, indicating its ability to act as an effective ORR electrocatalyst

A multi-center study on the attitudes of Malaysian emergency health care staff towards allowing family presence during resuscitation of adult patients

BACKGROUND The practice of allowing family members to witness on-going active resuscitation has been gaining ground in many developed countries since it was first introduced in the early 1990s. In many Asian countries, the acceptability of this practice has not been well studied. AIM We conducted a multi-center questionnaire study to determine the attitudes of health care professionals in Malaysia towards family presence to witness ongoing medical procedures during resuscitation. METHODS Using a bilingual questionnaire (in Malay and English language), we asked our respondents about their attitudes towards allowing family presence (FP) as well as their actual experience of requests from families to be allowed to witness resuscitations. Multiple logistic regression was used to analyze the association between the many variables and a positive attitude towards FP. RESULTS Out of 300 health care professionals who received forms, 270 responded (a 90% response rate). Generally only 15.8% of our respondents agreed to allow relatives to witness resuscitations, although more than twice the number (38.5%) agreed that relatives do have a right to be around during resuscitation. Health care providers are significantly more likely to allow FP if the procedures are perceived as likely to be successful (e.g., intravenous cannulation and blood taking as compared to chest tube insertion). Doctors were more than twice as likely as paramedics to agree to FP (p-value = 0.002). This is probably due to the Malaysian work culture in our health care systems in which paramedics usually adopt a 'follow-the-leader' attitude in their daily practice. CONCLUSION The concept of allowing FP is not well accepted among our Malaysian health care providers

COVID-19 Related Mobility Reduction: Heterogenous Effects on Sleep and Physical Activity Rhythms

Mobility restrictions imposed to suppress coronavirus transmission can alter physical activity (PA) and sleep patterns. Characterization of response heterogeneity and their underlying reasons may assist in tailoring customized interventions. We obtained wearable data covering baseline, incremental movement restriction and lockdown periods from 1824 city-dwelling, working adults aged 21 to 40 years, incorporating 206,381 nights of sleep and 334,038 days of PA. Four distinct rest activity rhythms (RARs) were identified using k-means clustering of participants' temporally distributed step counts. Hierarchical clustering of the proportion of time spent in each of these RAR revealed 4 groups who expressed different mixtures of RAR profiles before and during the lockdown. Substantial but asymmetric delays in bedtime and waketime resulted in a 24 min increase in weekday sleep duration with no loss in sleep efficiency. Resting heart rate declined 2 bpm. PA dropped an average of 38%. 4 groups with different compositions of RAR profiles were found. Three were better able to maintain PA and weekday/weekend differentiation during lockdown. The least active group comprising 51 percent of the sample, were younger and predominantly singles. Habitually less active already, this group showed the greatest reduction in PA during lockdown with little weekday/weekend differences. Among different mobility restrictions, removal of habitual social cues by lockdown had the largest effect on PA and sleep. Sleep and resting heart rate unexpectedly improved. RAR evaluation uncovered heterogeneity of responses to lockdown and can identify characteristics of persons at risk of decline in health and wellbeing.Comment: 30 pages, 3 main figures, 3 tables, 4 supplementary figure

Predictors of high-cost hospitalization in the treatment of acute coronary syndrome in Asia: findings from EPICOR Asia.

BACKGROUND: The EPICOR Asia (long-tErm follow-uP of antithrombotic management patterns In acute CORonary syndrome patients in Asia) study (NCT01361386) was an observational study of patients hospitalized for acute coronary syndromes (ACS) enrolled in 218 hospitals in eight countries/regions in Asia. This study examined costs, length of stay and the predictors of high costs during an ACS hospitalization. METHODS AND RESULTS: Data for patients hospitalized for an ACS (n = 12,922) were collected on demographics, medical history, event characteristics, socioeconomic and insurance status at discharge. Patients were followed up at 6 weeks' post-hospitalization for an ACS event to assess associated treatment costs from a health sector perspective. Primary outcome was the incurring of costs in the highest quintile by country and index event diagnosis, and identification of associated predictors. Cost data were available for 10,819 patients. Mean length of stay was 10.1 days. The highest-cost countries were China, Singapore, and South Korea. Significant predictors of high-cost care were age, male sex, income, country, prior disease history, hospitalization in 3 months before index event, no dependency before index event, having an invasive procedure, hospital type and length of stay. CONCLUSIONS: Substantial variability exists in healthcare costs for hospitalized ACS patients across Asia. Of concern is the observation that the highest costs were reported in China, given the rapidly increasing numbers of procedures in recent years. TRIAL REGISTRATION: NCT01361386

Cyclic Tetrapyrrolic Photosensitisers from the leaves of Phaeanthus ophthalmicus

<p>Abstract</p> <p>Background</p> <p>Twenty-seven extracts from 26 plants were identified as photo-cytotoxic in the course of our bioassay guided screening program for photosensitisers from 128 extracts prepared from 64 terrestrial plants in two different collection sites in Malaysia - Royal Belum Forest Reserve in the State of Perak and Gunung Nuang in the State of Selangor. One of the photo-cytotoxic extracts from the leaves of <it>Phaeanthus ophtalmicus </it>was further investigated.</p> <p>Results</p> <p>The ethanolic extract of the leaves from <it>Phaeanthus ophtalmicus </it>was able to reduce the <it>in vitro </it>viability of leukaemic HL60 cells to < 50% when exposed to 9.6 J/cm²of a broad spectrum light at a concentration of 20 μg/mL. Dereplication of the photo-cytotoxic fractions from <it>P. ophthalmicus </it>extracts based on TLC R_fvalues and HPLC co-injection of reference tetrapyrrolic compounds enabled quick identification of known photosensitisers, pheophorbide-<it>a</it>, pheophorbide-<it>a </it>methyl ester, 13²-hydroxypheophorbide-<it>a </it>methyl ester, pheophytin-<it>a </it>and 15¹-hydroxypurpurin 7-lactone dimethyl ester. In addition, compound <b>1 </b>which was not previously isolated as a natural product was also identified as 7-formyl-15¹-hydroxypurpurin-7-lactone methyl ester using standard spectroscopic techniques.</p> <p>Conclusions</p> <p>Our results suggest that the main photosensitisers in plants are based on the cyclic tetrapyrrole structure and photosensitisers with other structures, if present, are present in very minor amounts or are not as active as those with the cyclic tetrapyrrole structure.</p

Riverine sustainment 2012

Student Integrated ProjectIncludes supplementary materialThis technical report analyzed the Navy's proposed Riverine Force (RF) structure and capabilities for 2012. The Riverine Sustainment 2012 Team (RST) examined the cost and performance of systems of systems which increased RF sustainment in logistically barren environments. RF sustainment was decomposed into its functional areas of supply, repair, and force protection. The functional and physical architectures were developed in parallel and were used to construct an operational architecture for the RF. The RST used mathematical, agent-based and queuing models to analyze various supply, repair and force protection system alternatives. Extraction of modeling data revealed several key insights. Waterborne heavy lift connectors such as the LCU-2000 are vital in the re-supply of the RF when it is operating up river in a non-permissive environment. Airborne heavy lift connectors such as the MV-22 were ineffective and dominated by the waterborne variants in the same environment. Increase in manpower and facilities did appreciable add to the operational availability of the RF. Mean supply response time was the biggest factor effecting operational availability and should be kept below 24 hours to maintain operational availability rates above 80%. Current mortar defenses proposed by the RF are insufficient.N

Resisting Sleep Pressure:Impact on Resting State Functional Network Connectivity

In today's 24/7 society, sleep restriction is a common phenomenon which leads to increased levels of sleep pressure in daily life. However, the magnitude and extent of impairment of brain functioning due to increased sleep pressure is still not completely understood. Resting state network (RSN) analyses have become increasingly popular because they allow us to investigate brain activity patterns in the absence of a specific task and to identify changes under different levels of vigilance (e.g. due to increased sleep pressure). RSNs are commonly derived from BOLD fMRI signals but studies progressively also employ cerebral blood flow (CBF) signals. To investigate the impact of sleep pressure on RSNs, we examined RSNs of participants under high (19 h awake) and normal (10 h awake) sleep pressure with three imaging modalities (arterial spin labeling, BOLD, pseudo BOLD) while providing confirmation of vigilance states in most conditions. We demonstrated that CBF and pseudo BOLD signals (measured with arterial spin labeling) are suited to derive independent component analysis based RSNs. The spatial map differences of these RSNs were rather small, suggesting a strong biological substrate underlying these networks. Interestingly, increased sleep pressure, namely longer time awake, specifically changed the functional network connectivity (FNC) between RSNs. In summary, all FNCs of the default mode network with any other network or component showed increasing effects as a function of increased 'time awake'. All other FNCs became more anti-correlated with increased 'time awake'. The sensorimotor networks were the only ones who showed a within network change of FNC, namely decreased connectivity as function of 'time awake'. These specific changes of FNC could reflect both compensatory mechanisms aiming to fight sleep as well as a first reduction of consciousness while becoming drowsy. We think that the specific changes observed in functional network connectivity could imply an impairment of information transfer between the affected RSNs

Recurrent Fusion Genes in Gastric Cancer: CLDN18-ARHGAP26 Induces Loss of Epithelial Integrity.

Genome rearrangements, a hallmark of cancer, can result in gene fusions with oncogenic properties. Using DNA paired-end-tag (DNA-PET) whole-genome sequencing, we analyzed 15 gastric cancers (GCs) from Southeast Asians. Rearrangements were enriched in open chromatin and shaped by chromatin structure. We identified seven rearrangement hot spots and 136 gene fusions. In three out of 100 GC cases, we found recurrent fusions between CLDN18, a tight junction gene, and ARHGAP26, a gene encoding a RHOA inhibitor. Epithelial cell lines expressing CLDN18-ARHGAP26 displayed a dramatic loss of epithelial phenotype and long protrusions indicative of epithelial-mesenchymal transition (EMT). Fusion-positive cell lines showed impaired barrier properties, reduced cell-cell and cell-extracellular matrix adhesion, retarded wound healing, and inhibition of RHOA. Gain of invasion was seen in cancer cell lines expressing the fusion. Thus, CLDN18-ARHGAP26 mediates epithelial disintegration, possibly leading to stomach H(+) leakage, and the fusion might contribute to invasiveness once a cell is transformed. Cell Rep 2015 Jul 14; 12(2):272-285