Mechanical and thermal characterization of coir/hemp/polyester hybrid composite for lightweight applications

Individual applications of coir and hemp as reinforcement in composites have been exhaustively studied; however, their hybridization must also be investigated. In this context, this research investigates the utilization of coir and hemp fibers as reinforcements in a polyester-based hybrid composite system. The primary objective is to find out how these reinforcements affect the hybrid composites' mechanical (tensile, flexural, and impact) and thermo-gravimetric properties. To accomplish this, composite samples with varying weight proportions of coir and hemp fibers were fabricated, and extensive mechanical testing was performed. The findings from the tensile, flexural, and impact tests revealed an enhancement in the mechanical characteristics of the fabricated composites as the proportion of coir fiber grew and the proportion of hemp fiber reduced. The hybrid composite, containing 15% coir and 5% hemp fibers, had superior mechanical properties to the binary composite system. In addition, thermogravimetric analysis was performed to determine the thermal stability of the hybrid composites. Within a temperature range of 30 °C–800 °C, weight loss was observed, confirming the overall thermal resistance of the materials. Fourier Transform InfraRed Spectroscopy (FTIR) was used to determine the composite's chemical composition, revealing the presence of functional groups that contribute to the composite's performance. Utilizing Scanning Electron Microscopy (SEM), the surface morphology of hybrid composites was investigated, yielding valuable insights into the fiber-matrix interaction and composite structure. The results of this study demonstrate the potential of the coir/hemp/polyester hybrid composite as a lightweight material in a variety of industries

Evaluation of Preexisting Anti-Hemagglutinin Stalk Antibody as a Correlate of Protection in a Healthy Volunteer Challenge with Influenza A/H1N1pdm Virus

Influenza virus hemagglutinin (HA) surface glycoprotein is currently the primary target of licensed influenza vaccines. Recently, broadly reactive antibodies that target the stalk region of the HA have become a major focus of current novel vaccine development. These antibodies have been observed in humans after natural infection with influenza A virus, but the data are limited. Using samples and data from the uniquely controlled setting of an influenza A/H1N1 virus human challenge study of healthy volunteers, we performed a secondary analysis that for the first time explores the role of anti-HA stalk antibody as a human correlate of protection. An anti-HA stalk antibody enzyme-linked immunosorbent assay (ELISA) was performed on samples from 65 participants challenged with a 2009 H1N1pdm virus. Pre- and postchallenge anti-HA stalk titers were then correlated with multiple outcome measures to evaluate anti-HA stalk antibody titer as a correlate of protection. Anti-HA stalk antibody titers were present before challenge and rose in response to challenge in 64% of individuals. Those individuals with higher titers at baseline were less likely to develop shedding, but not less likely to develop symptoms. Similar to the hemagglutination inhibition (HAI) titer, the baseline anti-HA stalk antibody titer did not independently predict a decrease in the severity of influenza disease, while the antineuraminidase (neuraminidase inhibition [NAI]) titer did. As a correlate of protection, the naturally occurring anti-HA stalk antibody titer is predictive of a reduction of certain aspects of disease similar to HAI titer, but the NAI titer is the only identified correlate that is an independent predictor of a reduction of all assessed influenza clinical outcome measures

Influenza A Reinfection in Sequential Human Challenge: Implications for Protective Immunity and Universal Vaccine Development.

BACKGROUND: Identification of correlates of protection against human influenza A virus infection is important in development of broadly protective ( universal ) influenza vaccines. Certain assumptions underlie current vaccine developmental strategies including that infection with a particular influenza A virus should offer long term or lifelong protection against that strain, preventing reinfection. In this study we report observations made when 7 volunteers participated in sequential influenza challenge studies where they were challenged intranasally using the identical influenza A(H1N1)pdm09 virus approximately 1 year apart. We evaluate and describe the outcomes of these seven re-challenge participants and discuss what these results may suggest about correlates of protection and development of more broadly protective influenza vaccines. METHODS: Seven participants were enrolled in two viral challenge studies at 7.5 to 18.5 month intervals. Both challenge studies used the identical lot of influenza A (H1N1)pdm09 virus administered intranasally. We evaluated pre- and post-challenge HAI, NAI, and stalk antibody titers, peripheral blood leukocyte (PBL) host gene expression response profiles, daily viral detection via nasal wash, and clinical signs and symptoms. RESULTS: At least 3 of 7 participants demonstrated confirmed laboratory evidence of sequential infection with 5 of 7 demonstrating clinical evidence. CONCLUSION: The data presented in this report demonstrate that sequential infection with the identical influenza A virus can occur and suggest it may not be rare. These data raise questions about immune memory responses in an acute superficial respiratory mucosal infection and their implications in development of broadly protective influenza vaccines. Further investigation of these observations is warranted

Mucosal correlates of protection after influenza viral challenge of vaccinated and unvaccinated healthy volunteers

ABSTRACTThe induction of systemic antibody titers against hemagglutinin has long been the main focus of influenza vaccination strategies, but mucosal immunity has also been shown to play a key role in the protection against respiratory viruses. By vaccinating and challenging healthy volunteers, we demonstrated that inactivated influenza vaccine (IIV) modestly reduced the rate of influenza while predominantly boosting serum antibody titers against hemagglutinin (HA) and HA stalk, a consequence of the low neuraminidase (NA) content of IIV and the intramuscular route of administration. The viral challenge induced nasal and serum responses against both HA and NA. Correlations between mucosal IgA and serum IgG against specific antigens were low, whether before or after challenge, suggesting a compartmentalization of immune responses. Even so, volunteers who developed viral shedding for multiple days had lower baseline titers across both systemic and mucosal compartments as compared to those with no shedding or a single day of shedding. Regression analysis showed that pre-challenge HA inhibition titers were the most consistent correlate of protection across clinical outcomes combining shedding and symptoms, with NA inhibition titers and HA IgG levels only predicting the duration of shedding. Despite the inclusion of data from multiple binding and functional antibody assays against HA and NA performed on both serum and nasal samples, multivariate models were unable to account for the variability in outcomes, emphasizing our imperfect understanding of immune correlates in influenza and the importance of refining models with assessments of innate and cellular immune responses.IMPORTANCEThe devastating potential of influenza has been well known for over 100 years. Despite the development of vaccines since the middle of the 20th century, influenza continues to be responsible for substantial global morbidity and mortality. To develop next-generation vaccines with enhanced effectiveness, we must synthesize our understanding of the complex immune mechanisms culminating in protection. Our study outlines the differences in immune responses to influenza vaccine and influenza infection, identifying potential gaps in vaccine-induced immunity, particularly at the level of the nasal mucosa. Furthermore, this research underscores the need to refine our imperfect models while recognizing potential pitfalls in past and future attempts to identify and measure correlates of protection

Moral reasoning explained by personality traits and moral disengagement:a study among Dutch nurse practitioners and physician assistants

Aim To explore the direct and indirect effect of the personality meta‐traits ‘Stability’ and ‘Plasticity’ on moral reasoning among nurse practitioners and physician assistants. Background Moral reasoning is influenced by being prone to moral disengagement and personality traits. Moral disengagement is observed among professionals in many fields, including healthcare providers. Moral disengagement is known to be provoked by environmental stressors and influenced by certain personality traits. Design A cross‐sectional approach was used including self‐report questionnaires. Methods A convenience sample of Dutch nurse practitioners (N=67) and physician assistants (N=88) was surveyed via online questionnaires between January and March 2015, using: a) the Defining Issues Test; b) the BIG Five Inventory; and c) the Moral Disengagement Scale. Structural equation modeling (SEM) was employed for estimating the construct validity of two meta‐traits of personality and to test unidirectional influences on moral reasoning. Results Only the Stability trait was a direct predictor of moral reasoning whereas both Stability and Plasticity were precursors of moral disengagement. Both personality meta‐traits had statistically significant indirect effects on moral reasoning through a low level of moral disengagement. The influence of both personality traits on the level of moral reasoning was increased by strong self‐censure on entering into morally disengaged interactions. Conclusion The personality meta‐trait ‘Stability’ is an indicator of moral reasoning and is explained by a lower propensity to morally disengage among highly stable people. Although the meta‐trait Plasticity exerts an indirect effect through moral disengagement on moral reasoning, it is not a direct indicator of moral reasoning