Dual-layer remote phosphor structure: a novel technique to enhance the color quality scale and luminous flux of WLEDs

The effects of red light-emitting phosphor CaMgSi2O6:Eu2+,Mn2+ on the optical properties of single-layer remote phosphor structure (SRPS) and dual-layer remote phosphor structure (DRPS) are the focus of this study. The differences in color quality and luminous flux (LF) of white light-emitting diodes (WLEDs) between these two structures are also revealed and demonstrated based on the Mie theory. SRPS consists of one mixed phosphor layer betweenCaMgSi2O6:Eu2+,Mn2+ andYAG:Ce3+particles, while DRPS includes two separated layers: red phosphor layer and yellow phosphor layer. In this work, 5% SiO2 is added into the phosphor layers to increase scattering abilities. Discrepancies in structures greatly affect the optical characteristics of WLEDs. The results showed that the color rendering index (CRI) increased with the concentration in both structures with nearly equal values. Meanwhile, color quality scale (CQS) of DPRS is 74 at ACCTs ranging from 5600K to 8500K, higher than CQS of SRPS which is only 71 at 8500K. In addition, the luminous flux of DRPS is significantly higher than SRPS at 2% -14% of CaMgSi2O6:Eu2+,Mn2+. In summary, DRPS is better for color quality and lumen outputin comparison to SRPS and adding the right amount of red phosphor can enhance CQS and LF

A study on vegetative propagation of Huperzia serrata by cuttings in Sa Pa, Lao Cai

Huperzia serrata is a precious medicinal plant used in medicine to support and treat Alzheimer's disease. Currently, this species is in danger of extinction due to indiscriminate exploitation for commercial purposes. Furthermore, this species reproduces slowly and is difficult to cultivate artificially. The reproduction by spores of this species is very long and takes 15−20 years from the spore germination to mature plant, whereas asexual reproduction by tissue culture is also difficult. Therefore, cutting is an effective method to propagate this species on a large scale. In this study, we surveyed the factors affecting the survival rate, the rooting and the number of new leaves of the stem cuttings, including cutting length, growing substrate, and effects of growth-regulating hormones IBA (0 ppm, 500 ppm, 1000 ppm, 2000 ppm and 3000 ppm) and α-NAA (0 ppm, 10 ppm, 20 ppm, 30 ppm and 40 ppm). The experimental results showed that using cuttings of 6 cm in length treated with IBA at a concentration of 1000 ppm for 30 mins and cultured on the substrate mixture of soil, decomposed animal manure and rice husk at a ratio of 3:1:1 was the best for cuttings of H. serrata in Sa Pa. The results of this study will contribute to the conservation and development of genetic source of H. serrata in Vietnam.

Effect of addition of nanoclays on properties of vinyl ester

Vinyl ester resins have been used in many engineering applications such as matrix for composites used in ships, chemical reservoirs, pipes etc. It is desirable to enhance a few important properties of the resin such as flammability resistance, water absorption resistance, and fracture toughness. The addition of nanoclays has been shown to enhance these properties of epoxy resins. The work in this project is to investigate the effect of adding nanoclays on these properties of vinyl ester. Commercial vinyl esters usually contain styrene, which serves both as a diluent and a crosslinking agent. The presence of styrene complicates the incorporation of clays into the vinyl ester. As such two types of vinyl ester were used. One is commercial vinyl ester (Derakane 411- 350) which contains styrene, and the other is vinyl ester synthesized in the laboratory, which is kept free of styrene during the clay incorporation. Different types of clays were examined. Different methods of mixing the clays in the vinyl ester were investigated. The results show that among the different clays, composites made using vinyl ester and Cloisite 20A show better performance. If the mixing conditions are right, there is significant improvement in fracture toughness. However there is some reduction in flexural strength upon the addition of the clays.Peer reviewed: YesNRC publication: Ye

Miliutine C methyl ester, a new drimane sesquiterpene and bioactive alkaloids from the stems of <i>Miliusa velutina</i>

Previous results from the our research group have isolated numerous compounds, including novel ones, but the anticancer activity of Miliusa velutina has not been demonstrated. In this study, from the most active ethyl acetate extract of the stems of Miliusa velutina, seven compounds were isolated and determined structures, including a new drimane sesquiterpenoid compound named miliutine C methyl ester (1) and three bioactive alkaloids (5-7). These three alkaloids (5-7) exhibited strong anticancer activities against various cancer cell lines such as MCF-7, HepG2, HeLa, NCI H460 and normal fibroblasts. Especially, on MCF-7 and normal fibroblasts with values of IC50 (μM) in order for compounds 5 (3.38, 31.15), 6 (21.96, 102.00), 7 (7.90, greater than 300), to compare with positive control camptothecin (0.020, 4.51); which is highly noteworthy. These results contribute to elucidating and confirming the value of Miliusa velutina, similar to other published and folkloric findings.</p

Identification of potential anti-hyperglycemic compounds in <i>Cordyceps militaris</i> ethyl acetate extract: <i>in vitro</i> and <i>in silico</i> studies

Cordyceps militaris has been long known for valuable health benefits by folk experience and was recently reported with diabetes-tackling evidences, thus deserving extending efforts on screening for component-activity relationship. In this study, experiments were carried out to find the evidence, justification, and input for computations on the potential against diabetes-related protein structures: PDB-4W93, PDB-3W37, and PDB-4A3A. Liquid chromatography identified 14 bioactive compounds in the ethyl acetate extract (1–14) and quantified the contents of cordycepin (0.11%) and adenosine (0.01%). Bioassays revealed the overall potential of the extract against α-amylase (IC50 = 6.443 ± 0.364 mg.mL−1) and α-glucosidase (IC50 = 2.580 ± 0.194 mg.mL−1). A combination of different computational platforms was used to select the most promising candidates for applications as anti-diabetic bio-inhibitors, i.e. 1 (ground state: −888.49715 a.u.; dipole moment 3.779 Debye; DS¯ −12.3 kcal.mol−1; polarizability 34.7 Å3; logP − 1.30), 10 (ground state: −688.52406 a.u.; dipole moment 5.487 Debye; DS¯ −12.6 kcal.mol−1; polarizability 24.9 Å3; logP − 3.39), and 12 (ground state: −1460.07276 a.u.; dipole moment 3.976 Debye; DS¯ −12.5 kcal.mol−1; polarizability 52.4 Å3; logP − 4.39). The results encourage further experimental tests on cordycepin (1), mannitol (10), and adenosylribose (12) to validate their in-practice diabetes-related activities, thus conducive to hypoglycemic applications. Communicated by Ramaswamy H. Sarma</p

An observational study of breakthrough SARS-CoV-2 Delta variant infections among vaccinated healthcare workers in Vietnam

Background Data on breakthrough SARS-CoV-2 Delta variant infections in vaccinated individuals are limited. Methods We studied breakthrough infections among Oxford-AstraZeneca vaccinated healthcare workers in an infectious diseases hospital in Vietnam. We collected demographic and clinical data alongside serial PCR testing, measurement of SARS-CoV-2 antibodies, and viral whole-genome sequencing. Findings Between 11th–25th June 2021 (7-8 weeks after the second dose), 69 staff tested positive for SARS-CoV-2. 62 participated in the study. Most were asymptomatic or mildly symptomatic and all recovered. Twenty-two complete-genome sequences were obtained; all were Delta variant and were phylogenetically distinct from contemporary viruses obtained from the community or from hospital patients admitted prior to the outbreak. Viral loads inferred from Ct values were 251 times higher than in cases infected with the original strain in March/April 2020. Median time from diagnosis to negative PCR was 21 days (range 8–33). Neutralizing antibodies (expressed as percentage of inhibition) measured after the second vaccine dose, or at diagnosis, were lower in cases than in uninfected, fully vaccinated controls (median (IQR): 69.4 (50.7-89.1) vs. 91.3 (79.6-94.9), p=0.005 and 59.4 (32.5-73.1) vs. 91.1 (77.3-94.2), p=0.043). There was no correlation between vaccine-induced neutralizing antibody levels and peak viral loads or the development of symptoms. Interpretation Breakthrough Delta variant infections following Oxford-AstraZeneca vaccination may cause asymptomatic or mild disease, but are associated with high viral loads, prolonged PCR positivity and low levels of vaccine-induced neutralizing antibodies. Epidemiological and sequence data suggested ongoing transmission had occurred between fully vaccinated individuals