Search

The frequent variation of influenza virus hemagglutinin (HA) antigen is the main cause of influenza pandemic. Therefore, the study of B cell epitopes of HA is of great significance in the prevention and control of influenza virus. In this study, the cleavage vaccine of 2009 H1N1 influenza virus was used as immunogen, and the monoclonal antibodies (mAbs) were prepared by conventional hybridoma fusion and screening techniques. The characteristics of mAbs were identified by ELISA method, Western-blot test and hemagglutination inhibition test (HI). Using the obtained mAbs as a tool, the B cell epitopes of HA were predicted by ELISA blocking test, sandwich ELISA method and computer simulation method. Finally, four mAbs against HA antigen of H1N1 influenza virus were obtained. The results of ELISA and computer prediction showed that there were at least two types of epitopes on HA of influenza virus. This study provides experimental data for improving the prediction of HA epitopes of influenza viruses and developing potential influenza vaccines, and also provides a new method for the prediction of other pathogenic microorganisms.

A kind of cylinder sand mold was designed to investigate the heat-transfer-coefficients (HTCs) between aluminum alloy and organic/inorganic binder bonded sand mold during the solidification processes. Temperature during the solidification process was recorded and input into the simulation software. The inverse model of MAGMA was used to calculate the HTC based on the actual temperature. Results show that the temperature of the inorganic sand mold increased faster than the organic sand mold; while the temperature of the casting part with the inorganic sand mold decreased faster. The optimal HTCs between Al and the organic/inorganic sand mold are confirmed to be 300 to 700 and 1000 to 1800 W·m-2·K-1, respectively, along with the change of solid-liquid phase line. The simulated temperature curves show the same trend as the measured ones. The maximum deviation between the two temperature curves are 17.32 °C and 18.77 °C for castings by inorganic and organic sand molds.

Gas pores on the top face of engine crankcases which are produced by Low Pressure Die Casting (LPDC) have been studied. Micrographic analysis has been conducted to investigate the evolution of such kind of casting defects. Results show that the surface of such casting defects have meandering shapes and random sizes. Microstructures of the cross section of the defects displayed folded feather shapes, which can be produced by the folded oxide film into the melt during the filling process. Oxide inclusions have been found below the filter at the ingate area. Thus, it is confirmed that the folded oxide films came from turbulence of the metal in the die cavity. Numerical simulation has been carried out to study the filling behavior of the crankcase. Results show that gating velocity suddenly increased when the liquid metal got into the waterfall structure and led to the turbulence. Moreover, the air entrained behavior is related with the gating velocity. With increasing gating velocity, turbulence happened when metal confluences, and became more intensely in the middle of the casting due to its waterfall structure. Finally, this kind of casting defect was confirmed as gas entrainment.

Low Pressure Die Casting (LPDC) is widely used in crankcase production. Owing to the unstable production situation and the complex shape of crankcase, porosity defect usually occurs in LPDC process which leads to loss in quality and productivity. In this paper, we apply data mining methods to predict the porosity defect in advance, so that we can take actions to prevent it from reoccurring in the next production part, thereby increasing the quality and productivity. To do it, firstly, we collect production data from a real-world casting line. Secondly, we prepare the data for prediction by feature extraction and feature selection. Thirdly, we apply an ensemble algorithm named Forest of Local Trees (FLT) for defect prediction. Finally, we present a thorough experimental study of the proposed method. The results show that our method outperforms other five algorithms on five real-world datasets in terms of three indicators, recall, precision and F-measure.

COVID-19 caused by a novel coronavirus SARS-CoV-2 emerged in Wuhan, Hubei province since December 2019, and caused a rapid outbreak throughout China and globally. Cities outside Hubei are also facing great challenge and require implementing of effective and feasible strategy in precision diagnosing novel coronavirus pneumonia (NCP).We described a multicenter prospective study on diagnostic strategy of suspected NCP patients from January 22nd to February 9th, 2020 in Eastern China cities. Nasopharyngeal swabs were collected from the patients. The epidemiological characteristics, clinical symptoms, laboratory assessments, and computed tomographic (CT) scans were obtained. Pathogen screen were performed including RT-PCR, multiplex PCR, rapid flu antigen tests and mNGS.We enrolled 53 suspected NCP patients, among whom 20 were laboratory-confirmed. Fourteen (70%) and 3 (15%) patients were positive for the first and second SARS-CoV-2 RT-PCR test, respectively. All NCP patients were positive for mNGS. Chest CT images and the symptoms of early stage NCP patients were similar to other viral pneumonia patients. We identified 11 of 20 co-infections in NCP cases, including regular respiratory virus, fungi and bacteria synchronously. Genomic analysis showed that 8 of 10 cases had no mutation in virus genome, while 2 cases had only one single mutation in N gene.Our study discovered that a combination of chest CT, SARS-CoV-2 RT-PCR and multi-plex PCR is recommended in regions outside Hubei province. Co-infection of other pathogens with SARS-CoV-2 exists and should be acknowledged. Repeated sampling, change of specimen type or metagenomics sequencing could further facilitate during critical clinical cases.

Fe

Nanofiltration (NF) membranes with simultaneous high rejection of divalent cations and anions and high water permeation were designed and fabricated via interfacial polymerization (IP) on three-channel capillary ultrafiltration (UF) membranes. MWCNTs-COOH were modified with poly(amidoamine) (PAMAM) and the as-synthesized MWCNTs-PAMAM were embedded into the inner polyamide skin-layer of the NF membranes by incorporating them into a piperazine (PIP) aqueous solution, followed by IP with trimesoyl chloride (TMC). The rigid MWCNTs and the dendrimer PAMAM molecules endow the as-fabricated NF membranes with high porosity and good hydrophilicity. Additionally, the –NH2 groups of PAMAM introduce some positive sites into the polyamide layer. The as-prepared NF membranes with incorporated MWCNTs-PAMAM exhibit a pure water flux of 48.7 L m−2 h−1 and 92.6% and 88.5% rejection for Na2SO4 and MgCl2, respectively, at 4 bar. Moreover, the NF membranes display high rejection for sulfates and metal cations, including heavy metal ions. The practicability of the membranes for mine-wastewater treatment was tested, and the membranes showed above 80% rejection of heavy metals and solution flux of about 30 L m−2 h−1. In addition, their separation performance and stability were satisfactory during the long-term run. The high rejection of the membranes for metal cations is ascribed to the positive sites offered by MWCNTs-PAMAM and the narrow membrane pores since both electrostatic repulsion and size exclusion play a role during membrane filtration. The good separation performance of the membranes for multivalent anions and heavy metal cations illustrates their potential for applications in heavy metal wastewater treatment.

Water pollution is a growing issue that requires remediation. Surfactants, used in many domestic and industrial applications, are one of the emerging contaminants that require immediate concern. Removing low-concentration surfactants using nanofiltration (NF) membrane is a study that deserves attention. In this case, a mixed polyamide-based NF membrane was fabricated via interfacial polymerization (IP) using polyethylenimine (PEI) and piperazine (PIP) as monomers in aqueous solution. UiO66-NH2 and UiO66 were synthesized and incorporated into the polyamide layer to enhance the permeability of the prepared NF membranes. The pure water flux of the NF membranes reached 16.6 L m−2 h−1 bar−1 when UiO66-NH2 concentration in aqueous solution is 0.005 wt%, and the membrane showed decent rejection to divalent salts, 96.5% to MgCl2 and 85.6% to Na2SO4. The prepared membranes were utilized to remove surfactants with the concentration (100 mg L−1) below the critical micelle concentration (CMC) from water, and they showed good removal to both anionic and cationic surfactants. In addition, the durability of the fabricated NF membranes is acceptable. This work provides a feasible strategy for the fabrication of highly permeable NF membranes and demonstrates the capability of NF membrane for surfactants removal.

High-performance nanofiltration (NF) membranes have profound implications for water purification. Here, we reported a novelty polyamide NF membrane through introducing bis (2-hydroxyethyl) dimethyl-ammonium chloride (BHDA) in interfacial polymerization (IP) process on three-channel substrate membrane. This new monomer bearing abundant quaternary ammonium (N+) and hydroxyl could participate in the reaction between piperazine (PIP) and trimesoyl chloride (TMC). Then, not only was positive charge introduced into the NF membrane, but the hydrophilic of the resultant NF membrane was also significantly improved. Thus, the as-prepared PIP/BHDA-TMC (MPQ) membrane exhibited enhanced pure water flux (12.9 L·m−2·h−1·bar−1) which is 2.4 times as high as that of the PIP-TMC (MP) membrane, coupled with the salt rejection sequence as MgSO4 (93.46%) > Na2SO4 (91.61%) > MgCl2 (88.15%) > NaCl (22.03%). Meanwhile, MPQ exhibited a promising separation performance to various heavy metal salts (96.43% CuSO4, 96.16% ZnSO4, 91.69% Cu(NO3)2, 89.69% ZnCl2, 88.37% Pb(NO3)2). The stability of MPQ was tested with simulated wastewater, and the results illustrated that it has a potential applicability for heavy metals removal.

Fe3O4/Polyvinylidene fluoride (PVDF) three-channel hollow fiber catalytic membrane was successfully fabricated via non-solvent induced phase inversion and used for organic wastewater degradation in this work. The effects of Fe3O4 nanoparticles addition on the surface and cross-section morphologies, hydrophilicity and thermal properties of the catalytic membrane were characterized by the field emission scanning electron microscopy (SEM), water contact angle and thermogravimetric analysis (TGA), respectively. The obtained catalytic membrane exhibited good hydrophilicity, a high pure water flux of 175.8 L m−2 h−1 and a high removal of methylene blue (up to 97.6%) with Fenton catalytic reaction. Meanwhile, the catalytic membrane shows excellent anti-fouling property due to the presence of Fenton reaction. Our results show that Fe3O4/PVDF three-channel hollow fiber catalytic membrane was a promising alternative for the degradation of organic contaminants.