Background With the unprecedented morbidity and mortality associated with the COVID-19 pandemic, a vaccine against COVID-19 is urgently needed. We investigated CoronaVac (Sinovac Life Sciences, Beijing, China), an inactivated vaccine candidate against COVID-19, containing inactivated severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), for its safety, tolerability and immunogenicity. Methods In this randomised, double-blind, placebo-controlled, phase 1/2 clinical trial, healthy adults aged 18-59 years were recruited from the community in Suining County of Jiangsu province, China. Adults with SARS-CoV-2 exposure or infection history, with axillary temperature above 37•0°C, or an allergic reaction to any vaccine component were excluded. The experimental vaccine for the phase 1 trial was manufactured using a cell factory process (CellSTACK Cell Culture Chamber 10, Corning, Wujiang, China) , whereas those for the phase 2 trial were produced through a bioreactor process (ReadyToProcess WAVE 25, GE, Umea, Sweden). The phase 1 trial was done in a dose-escalating manner. At screening, participants were initially separated (1:1), with no specific randomisation, into two vaccination schedule cohorts, the days 0 and 14 vaccination cohort and the days 0 and 28 vaccination cohort, and within each cohort the first 36 participants were assigned to block 1 (low dose CoronaVac [3 μg per 0•5 mL of aluminium hydroxide diluent per dose) then another 36 were assigned to block 2 (high-dose Coronavc [6 μg per 0•5 mL of aluminium hydroxide diluent per dse]). Within each block, participants were randomly assigned (2:1), using block randomisation with a block size of six, to either two doses of CoronaVac or two doses of placebo. In the phase 2 trial, at screening, participants were initially separated (1:1), with no specific randomisation, into the days 0 and 14 vaccination cohort and the days 0 and 28 vaccination cohort, and participants were randomly assigned (2:2:1), using block randomisation with a block size of five, to receive two doses of either low-dose CoronaVac, high-dose CoronaVac, or placebo. Participants, investigators, and laboratory staff were masked to treatment allocation. The primary safety endpoint was adverse reactions within 28 days after injection in all participants who were given at least one dose of study drug (safety population). The primary immunogenic outcome was seroconversion rates of neutralising antibodies to live SARS-CoV-2 at day 14 after the last dose in the days 0 and 14 cohort, and at day 28 after the last dose in the days 0 and 28 cohort in participants who completed their allocated two-dose vaccination schedule (per-protocol population). This trial is registered with ClinicalTrials.gov, NCT04352608, and is closed to accrual. Findings Between April 16 and April 25, 2020, 144 participants were enrolled in the phase 1 trial, and between May 3 and May 5, 2020, 600 participants were enrolled in the phase 2 trial. 743 participants received at least one dose of investigational product (n=143 for ph...

Previous research on cluster-based retrieval has been inconclusive as to whether it does bring improved retrieval effectiveness over document-based retrieval. Recent developments in the language modeling approach to IR have motivated us to re-examine this problem within this new retrieval framework. We propose two new models for cluster-based retrieval and evaluate them on several TREC collections. We show that cluster-based retrieval can perform consistently across collections of realistic size, and significant improvements over document-based retrieval can be obtained in a fully automatic manner and without relevance information provided by human.

Phlorotannins are a group of complex polymers of phloroglucinol (1,3,5-trihydroxybenzene), which are unique compounds from marine brown algae. In our present study, a procedure for extraction and enrichment of phlorotannins from S. fusiforme with highly antioxidant potentials was established. After comparison of different extraction methods, the optimal extraction conditions were established as follows. The freeze-dried seaweed powder was extracted with 30% ethanol-water solvent with a solid/liquid ratio of 1:5 at temperature of 25 °C for 30 min. After extraction, the phlorotannins were fractioned by different solvents, among which the ethyl acetate fraction exhibited both the highest total phlorotannin content (88.48 ± 0.30 mg PGE/100 mg extract) and the highest antioxidant activities. The extracts obtained from these locations were further purified and characterized using a modified UHPLC-QQQ-MS method. Compounds with 42 different molecular weights were detected and tentatively identified, among which the fuhalol-type phlorotannins were the dominant compounds, followed by phlorethols and fucophlorethols with diverse degree of polymerization. Eckol-type phlorotannins including some newly discovered carmalol derivatives were detected in Sargassum species for the first time. Our study not only described the complex phlorotannins composition in S. fusiforme, but also highlighted the challenges involved in structural elucidation of these compounds.

Previous research has shown that passage-level evidence can bring added benefits to document retrieval when documents are long or span different subject areas. Recent developments in language modeling approach to IR provided a new effective alternative to traditional retrieval models. These two streams of research motivate us to examine the use of passages in a language model framework. This paper reports on experiments using passages in a simple language model and a relevance model, and compares the results with document-based retrieval. Results from the INQUERY search engine, which is not based on a language modeling approach, are also given for comparison. Test data include two heterogeneous and one homogeneous document collections. Our experiments show that passage retrieval is feasible in the language modeling context, and more importantly, it can provide more reliable performance than retrieval based on full documents.

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We have investigated the magnetization dynamics of sputtered Co 40 Fe 40 B 20 thin films in a wide range of thicknesses used as free layers in MgO-based magnetic tunnel junctions, with the technique of broadband ferromagnetic resonance (FMR). We have observed a large interface-induced magnetic perpendicular anisotropy in the thin film limit. The out-of-plane angular dependence of the FMR measurement revealed the contributions of two different damping mechanisms in thick and thin film limits. In thinner films (< 2 nm), two-magnon scattering and inhomogeneous broadening are significant for the FMR linewidth, while the Gilbert damping dominates the linewidth in thicker films (! 4 nm). Lastly, we have observed an inverse scaling of Gilbert damping constant with film thickness, and an intrinsic damping constant of 0.004 in the CoFeB alloy film is determined. V

Recently, a conformal surface plasmon (CSP) structure has been successfully proposed, which is very promising for application of planar plasmonic devices in the frequency ranging from microwave to mid-infrared [Proc. Natl. Acad. Sci. U.S.A. 110, 40-45 (2013)]. Here we investigated the dispersions and electromagnetic (EM) field patterns of a symmetric CSP structure in which the two sides of the planar metal strip are symmetrically corrugated by groove arrays. The symmetric CSP structure can support both the symmetric mode (even mode) and the anti-symmetric mode (odd mode) of surface wave propagation. Based on the even mode, we analyzed the EM wave coupling between two adjacent symmetry CSP strips, and then designed and analyzed two planar CSP waveguide devices in the terahertz frequency: a frequency splitter and a 3 dB directional coupler. To verify the functionality and performance of these waveguide devices, we scaled down the working frequency to microwave and designed similar devices with scaled geometry. We implemented microwave experiments on the fabricated prototypes, and the tested device performances have clearly validated the functionality of our designs. The symmetric CSP structure is believed to be very applicable in future design of novel planar plasmonic device and circuitry.

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