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In this investigation, an effort has been made to analyze the abrasive wear characteristics of cotton grass (CG) reinforced epoxy composites through the hand layup technique. The abrasive wear test is conducted on a dry sand abrasion test machine based on ASTM G65; according to this, the specimen is fabricated with a dimension of 76 × 25 mm2. The engineering application for the composites requires that it should have high wear resistance, low water absorption, and robust strength. Mechanical properties such as tensile strength, hardness, and impact energy are experimentally investigated and optimized and the optimum results are obtained at 9 wt% of CG contents with magnitude of tensile strength of 45.81 MPa, hardness of 34.17 Hv, and impact energy of 2.2 J. The multiple responses of composites are analyzed using the Gray–Taguchi method and optimal factors settings to improve multiple responses, i.e., abrasive wear rate, water absorption, tensile strength, hardness, and impact energy. The results showed that the most critical factor influencing the properties of composites is CG content (9 wt%), accompanied by sliding velocity (96 m/s), normal load (15 N), and sliding distance (60 m). Scanning electron microscopy is used to analyze the composites’ worn surfaces to investigate the potential wear mechanism.

Background: Recombinant pertussis vaccines inducing long-lasting immune responses could help to control the rise in pertussis. We here report on persisting antibody responses 2 and 3 years after booster vaccination with a new generation recombinant acellular pertussis vaccine. Methods: Participants of a phase 2/3 randomised-controlled clinical trial with a monovalent pertussis vaccine containing genetically inactivated pertussis toxin (aPgen) or its tetanus and diphtheria toxoids combination (TdaPgen), or a chemically detoxified comparator vaccine (Tdapchem), (originally conducted between July and August 2015) were invited to participate in observational studies of persisting antibody responses 2 and 3 years after vaccination. Serum IgG against pertussis toxin (PT-IgG) and filamentous hemagglutinin (FHA-IgG) were assessed by ELISA, and PT-neutralising antibodies (PT-Nab) by Chinese Hamster Ovary cell assay. Findings: Waning of antibodies stabilised in aPgen and TdaPgen vaccinees 2 and 3 years after vaccination. Three years post-vaccination PT-neutralising antibodies remained 4·6-fold (95% Confidence Interval (CI) 2·6–8·1) and 3·7-fold (95% CI 2·2–6·1) higher, PT-IgG antibodies 3·0-fold (95% CI 2·2–4·1) and 2·5-fold (95% CI 1·9–3·3) higher, and FHA-IgG antibodies 1·8-fold (95% CI 1·3–2·5) and 1·6-fold (95% CI 1·2–2·1) higher than baseline in aPgen and TdaPgen recipients, respectively. In the Tdapchem group, PT-neutralising and PT-IgG and FHA-IgG antibodies were back at baseline levels 2 years post-vaccination. Three years post-vaccination seroconversion rates for PT-neutralising antibodies were 65·0% (95% CI 44·1–85·9) and 55·0% (95% CI 33·2–76·8) in aPgen and TdaPgen recipients, respectively. Interpretation: Considering the persistence of elevated antibody responses 3 years post-booster vaccination, genetically detoxified monovalent aPgen and TdaPgen vaccines can be expected to induce longer-lasting protection than chemically inactivated Tdap vaccines. Funding: BioNet-Asia

Background: An acellular Pertussis (aP) vaccine containing recombinant genetically detoxified Pertussis Toxin (PTgen), Filamentous Hemagglutinin (FHA) and Pertactin (PRN) has been developed by BioNet-Asia (BioNet). We present here the results of the first clinical study of this recombinant aP vaccine formulated alone or in combination with tetanus and diphtheria toxoids (TdaP). Methods: A phase I/II, observer-blind, randomized controlled trial was conducted at Mahidol University in Bangkok, Thailand in healthy adult volunteers aged 18–35 y. The eligible volunteers were randomized to receive one dose of either BioNet's aP or Tetanus toxoid-reduced Diphtheria toxoid-acellular Pertussis (TdaP) vaccine, or the Tdap Adacel® vaccine in a 1:1:1 ratio. Safety follow-up was performed for one month. Immunogenicity was assessed at baseline, at 7 and 28 d after vaccination. Anti-PT, anti-FHA, anti-PRN, anti-tetanus and anti-diphtheria IgG antibodies were assessed by ELISA. Anti-PT neutralizing antibodies were assessed also by CHO cell assay. Results: A total of 60 subjects (20 per each vaccine group) were enrolled and included in the safety analysis. Safety laboratory parameters, incidence of local and systemic post-immunization reactions during 7 d after vaccination and incidence of adverse events during one month after vaccination were similar in the 3 vaccine groups. One month after vaccination, seroresponse rates of anti-PT, anti-FHA and anti-PRN IgG antibodies exceeded 78% in all vaccine groups. The anti-PT IgG, anti-FHA IgG, and anti-PT neutralizing antibody geometric mean titers (GMTs) were significantly higher following immunization with BioNet's aP and BioNet's TdaP than Adacel® (P< 0.05). The anti-PRN IgG, anti-tetanus and anti-diphtheria GMTs at one month after immunization were comparable in all vaccine groups. All subjects had seroprotective titers of anti-tetanus and anti-diphtheria antibodies at baseline. Conclusion: In this first clinical study, PTgen-based BioNet's aP and TdaP vaccines showed a similar tolerability and safety profile to Adacel® and elicited significantly higher immune responses to PT and FHA.