This paper deals with the effect of input parameters of Powder Mixed Electric Discharge Machining (PMEDM) process on the surface roughness when processing cylindrical shaped parts. In this work, the ...workpiece material is 90CrSi alloy tool steel and the nanopowder is silicon carbide. Also, five input parameters including the pulse on time, the pulse off time, the powder concentration, the current and the server voltage were selected to investigate their influence on the surface roughness. Taguchi method and ANOVA analysis were used and the effect of input parameters on the surface roughness was presented. Moreover, optimum input parameters for minimum surface roughness was suggested.
Falls among the elderly are an important global health problem. This study assesses knowledge regarding risk factors of falls, as well as attitudes and practices towards fall prevention among older ...adults in the rural community. A cross-sectional study was performed in four rural communes in Thai Binh province, Vietnam. A total of 3038 older people were recruited. Knowledge was assessed by using Falls Risk Awareness Questionnaire. Questions about attitudes were based on the Health Belief Model. Other questions regarding attitudes and practices regarding fall prevention were also asked. Multivariate regression was performed to identify associated factors with knowledge, attitudes and practices. Results showed that the mean score of knowledge regarding risk factors of falls was low at 11.37/32. The highest scores were observed in terms of drug aspects, followed by medical condition and behavioural aspects. Older people mostly agreed with perceived severity, susceptibility, benefits and barriers, but their attitudes about cues to action, health motivation and actions were most neutral. Meanwhile, more than half of the participants practised recommended fall preventive measures. To conclude, health education interventions and fall prevention services that enhance community-based fall prevention knowledge, attitudes and practices for older adults should be performed to reduce the burden of falls in this population.
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DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Trends in the public perception and awareness of COVID-19 over time are poorly understood. We conducted a longitudinal study to analyze characteristics and trends of online information during a major ...COVID-19 outbreak in Da Nang province, Vietnam in July-August 2020 to understand public awareness and perceptions during an epidemic.
We collected online information on COVID-19 incidence and mortality from online platforms in Vietnam between 1 July and 15 September, 2020, and assessed their trends over time against the epidemic curve. We explored the associations between engagement, sentiment polarity, and other characteristics of online information with different outbreak phases using Poisson regression and multinomial logistic regression analysis. We assessed the frequency of keywords over time, and conducted a semantic analysis of keywords using word segmentation.
We found a close association between collected online information and the evolution of the COVID-19 situation in Vietnam. Online information generated higher engagements during compared to before the outbreak. There was a close relationship between sentiment polarity and posts' topics: the emotional tendencies about COVID-19 mortality were significantly more negative, and more neutral or positive about COVID-19 incidence. Online newspaper reported significantly more information in negative or positive sentiment than online forums or social media. Most topics of public concern followed closely the progression of the COVID-19 situation during the outbreak: development of the global pandemic and vaccination; the unfolding outbreak in Vietnam; and the subsiding of the outbreak after two months.
This study shows how online information can reflect a public health threat in real time, and provides important insights about public awareness and perception during different outbreak phases. Our findings can help public health decision makers in Vietnam and other low and middle income countries with high internet penetration rates to design more effective communication strategies during critical phases of an epidemic.
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DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Alginate/lignin is a synthetic polymer rich in biological activity and is of great interest. Alginate is extracted from seaweed and lignin is extracted from corn stalks and leaves. In this paper, ...antioxidant activities of alginate/lignin were evaluated, such as total antioxidant activity, reducing power activity, DPPH free radical scavenging activity, and α-glucosidase inhibition activity. Anticancer activity was evaluated in three cell lines (Hep G2, MCF-7, and NCI H460) and fibroblast. Physico-chemistry characteristics of alginate/lignin were determined through FTIR, DSC, SEM_EDS, SEM_EDS mapping, XRD, XRF, and
H-NMR. The acute toxicity of alginate/lignin was studied on
mice. The results demonstrated that alginate/lignin possessed antioxidant activity, such as the total antioxidant activity, and reducing power activity, especially the α-glucosidase inhibition activity, and had no free radical scavenging activity. Alginate/lignin was not typical in cancer cell lines. Alginate/lignin existed in a thermally stable and regular spherical shape in the investigated thermal region. Six metals, three non-metals, and nineteen oxides were detected in alginate/lignin. Some specific functional groups of alginate and lignin did not exist in alginate/lignin crystal. Elements, such as C, O, Na, and S were popular in the alginate/lignin structure. LD
and LD
of alginate/lignin in mice were 3.91 g/kg and 9.77 g/kg, respectively. Alginate/lignin has potential for applications in pharmaceutical materials, functional foods, and supporting diabetes treatment.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
Trials of fluoxetine for recovery after stroke report conflicting results. The Assessment oF FluoxetINe In sTroke recoverY (AFFINITY) trial aimed to show if daily oral fluoxetine for 6 months after ...stroke improves functional outcome in an ethnically diverse population.
AFFINITY was a randomised, parallel-group, double-blind, placebo-controlled trial done in 43 hospital stroke units in Australia (n=29), New Zealand (four), and Vietnam (ten). Eligible patients were adults (aged ≥18 years) with a clinical diagnosis of acute stroke in the previous 2–15 days, brain imaging consistent with ischaemic or haemorrhagic stroke, and a persisting neurological deficit that produced a modified Rankin Scale (mRS) score of 1 or more. Patients were randomly assigned 1:1 via a web-based system using a minimisation algorithm to once daily, oral fluoxetine 20 mg capsules or matching placebo for 6 months. Patients, carers, investigators, and outcome assessors were masked to the treatment allocation. The primary outcome was functional status, measured by the mRS, at 6 months. The primary analysis was an ordinal logistic regression of the mRS at 6 months, adjusted for minimisation variables. Primary and safety analyses were done according to the patient's treatment allocation. The trial is registered with the Australian New Zealand Clinical Trials Registry, ACTRN12611000774921.
Between Jan 11, 2013, and June 30, 2019, 1280 patients were recruited in Australia (n=532), New Zealand (n=42), and Vietnam (n=706), of whom 642 were randomly assigned to fluoxetine and 638 were randomly assigned to placebo. Mean duration of trial treatment was 167 days (SD 48·1). At 6 months, mRS data were available in 624 (97%) patients in the fluoxetine group and 632 (99%) in the placebo group. The distribution of mRS categories was similar in the fluoxetine and placebo groups (adjusted common odds ratio 0·94, 95% CI 0·76–1·15; p=0·53). Compared with patients in the placebo group, patients in the fluoxetine group had more falls (20 3% vs seven 1%; p=0·018), bone fractures (19 3% vs six 1%; p=0·014), and epileptic seizures (ten 2% vs two <1%; p=0·038) at 6 months.
Oral fluoxetine 20 mg daily for 6 months after acute stroke did not improve functional outcome and increased the risk of falls, bone fractures, and epileptic seizures. These results do not support the use of fluoxetine to improve functional outcome after stroke.
National Health and Medical Research Council of Australia.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
We prepared epoxidized soybean oil (ESO) grafted with carboxyl-terminated poly(acrylonitrile-co-butadiene) (CTBN) (ESO-g-CTBN) by a ring-opening reaction between the epoxide group and the carboxyl ...group. The structural features of the resulting product were determined using modern analytical techniques, such as Fourier transform infrared (FTIR) spectroscopy, proton nuclear magnetic resonance (1H NMR) spectroscopy, and gel permeation chromatography (GPC). The ESO-g-CTBN was applied as a toughener for an epoxy resin-based composite that was fabricated by blending the epoxy resin with diethylenetriamine (DETA) as the curing agent. The main aim of this procedure is to simultaneously improve the mechanical properties and fracture toughness of a bisphenol A-based epoxy resin. When 15 phr of ESO-g-CTBN was added to the EP/DETA mixture, the resin fracture toughness (KIC) and tensile strength increased from 0.65 to 1.09 MPa m1/2 and from 34.42 to 42.55 MPa, respectively. The ESO-g-CTBN existed in the EP matrix as a separate phase and induced an increase in the KIC via stopping crack growth or changing the crack direction.The epoxydized soybean oil grafted with CTBN (ESO-g-CTBN) was synthesized from ring opening reaction between epoxide group and carboxyl group. The ESO-g-CTBN help to improve the fracture toughness of epoxy resin by the mechanism as shown in the figure.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
A superior approach is presented to study quantitatively fine structure of C‐doped ZnO nanostructure using transmission electron microscopy (TEM) from which the role of carbon in ZnO crystal to form ...ferromagnetism is revealed at the first time. Electron diffraction in TEM shows Wurtzite structure in the nanoparticles with lattice parameters (a = 0.327 ± 0.03 nm and c = 0.529 ± 0.04 nm) slightly different from the original structure. Interestingly, the Zn–C bonding with a bonding length of 2.58 Å is experimentally determined using atomic pair distribution function (PDF) calculated from electron diffraction data. Together with other bondings, such as C–C, Zn–O obtained from the PDF, this demonstrates migration of C atoms into ZnO crystal to substitute O vacancies. This is furthermore visualized by high‐resolution TEM imaging and elemental mapping, and strongly supports the proposal of origin of ferromagnetism in the C‐doped ZnO nanoparticles where the s–p and p–p hybridizations formed by C2p–Zn4s, and O2p–C2p orbitals are believed to cause ferromagnetism.
The paper presents a superior approach to understand the role of carbon in ZnO to form ferromagnetism. ZnC and CC bonds with the lengths of 2.58 and 1.42 Å, respectively are determined using atomic pair distribution function calculated from electron diffraction in transmission electron microscopy indicating substitution of C for O to form the ferromagnetism via s–p and p–p orbital hybridizations.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
In recent years, serosurveillance has gained momentum as a way of determining disease transmission and immunity in populations, particularly with respect to vaccine-preventable diseases. At the end ...of 2017, the Oxford University Clinical Research Unit and the National Institute of Hygiene and Epidemiology held a meeting in Vietnam with national policy makers, researchers, and international experts to discuss current seroepidemiologic projects in Vietnam and future needs and plans for nationwide serosurveillance. This report summarizes the meeting and the plans that were discussed to set up nationwide serosurveillance in Vietnam.
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DOBA, IZUM, KILJ, NUK, ODKLJ, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Eight polythiophene derivatives containing pyrazoline side groups were synthesized by a chemical oxidative coupling polymerization using FeCl
3
. The crystal structures of four monomers were ...determined which confirm the almost perpendicular orientation of the thiophene and pyrazoline rings, while the other substituents are more coplanar. Analyses of IR,
1
H-NMR, Raman and UV-Vis spectra demonstrated that the suggested polymerization was successful to generate the synthesized polythiophenes with the expected structures. The morphology of the synthesized polythiophenes was studied by SEM. The different substituents attached to the 1- and 3-positions of the pyrazoline side chain led to differences in optical properties, electrical conductivity, and thermal stability of the synthesized polythiophenes. By adding a pyrazoline side chain to polythiophenes, some polymers achieve good solubility, electrical conductivity of about 1.3 × 10
-6
S/cm, high fluorescence intensity (above 40,000 a.u.) at 505-550 nm and thermal stability up to 590°C in the air.
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DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
Photocatalysis under low energy light is of great importance for study of environmental pollution impact. There is an increasing demand for preparing integrated photocatalysts to show their potential ...in persistent organic compound degradation under visible and near-infrared light. In this work, we have reported the structural combination of three functional components of NaYF
4
:Yb,Er, TiO
2
, Cu into photocatalytic nanocomposites for near-infrared light (NIR) photocatalysis. Uniform and monodisperse NaYF
4
:Yb,Er nanocubes prepared by hydrothermolysis were used as a photon converter and they were combined with TiO
2
semiconductor and Cu co-catalysts by sequential deposition to fabricate NIR-active photocatalysts. The Cu/TiO
2
/NaYF
4
:Yb,Er nanocomposites were investigated for the organic degradation under NIR light. The Cu/TiO
2
/NaYF
4
:Yb,Er photocatalysts were photoactive with NIR light and full decomposition of methylene blue was reached for 90 min. These nanocomposites exhibit the NIR photocatalytic response caused by the NIR light absorption and photon electron transfer over NaYF
4
:Yb,Er, TiO
2
, and Cu components.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OBVAL, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
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