Rotavirus Specific Maternal Antibodies and Immune Response to RV3-BB Neonatal Rotavirus Vaccine in New Zealand

Background: Rotavirus specific maternal antibodies acquired passively via placental and/or breast milk may contribute to the reduced oral rotavirus vaccine efficacy observed in children in developing countries. This study aimed to investigate the effect of rotavirus specific maternal antibodies on the serum IgA response or stool excretion of vaccine virus after any dose of an oral neonatal rotavirus vaccine, RV3-BB, in parallel to a Phase IIa clinical trial conducted at Dunedin Hospital, New Zealand. Methods: Rotavirus specific IgG and serum neutralizing antibody (SNA) levels in cord blood and IgA levels in colostrum and breast milk samples collected ~4 weeks, ~20 weeks and ~28 weeks after birth were measured. Infants were randomised to receive the first dose of vaccine at 0–5 days after birth (neonatal schedule) or at 8 weeks (infant schedule). Breast feeding was with-held for 30 minutes before and after vaccine administration. Data for IgA response and stool vaccine virus excretion after RV3-BB rotavirus vaccine was obtained from the Phase IIa clinical trial. The relationship between rotavirus specific IgA in colostrum or breast milk at the time of first active dose of RV3-BB vaccine and rotavirus specific IgG and SNA levels in cord blood, and level of IgA response and stool vaccine virus excretion after three doses of vaccine was assessed using linear and logistic regression. The relationship between rotavirus specific IgA in colostrum and rotavirus specific IgG a nd SNA levels in cord blood, and level of IgA response and stool vaccine virus excretion after a single neonatal dose of vaccine in the neonatal schedule group was also assessed. Results: Twenty one infants in the neonatal schedule group and 19 infants in the infant schedule group received 3 doses of RV3-BB rotavirus vaccine and were included in the analysis. Rotavirus specific IgA in colostrum and breast milk at 4 weeks was identified in 14/21 (67%) and 14/17 (82%) of infants in the neonatal and infant schedule groups respectively. IgA responses after 3 doses were identified in 76% and 74% of infants in the neonatal and infant groups, stool excretion of vaccine virus in 71% and 79% of infants. There was no evidence of an association between IgA in colostrum or breast milk IgA at 4 weeks and IgA response or stool excretion after three doses of RV3-BB, or after one dose (neonatal schedule). There was little evidence of an association between cord IgG or SNA level and level of IgA response and stool excretion after one neonatal dose or after 3 doses of RV3-BB. Conclusions: The level of IgA in colostrum or breast milk and placental IgG and SNA did not affect the serum IgA response or stool excretion following three doses of RV3-BB Rotavirus Vaccine administered using a neonatal or infant schedule in New Zealand infants

Rotavirus Specific Maternal Antibodies and Immune Response to RV3-BB Neonatal Rotavirus Vaccine in New Zealand

Background: Rotavirus specific maternal antibodies acquired passively via placental and/or breast milk may contribute to the reduced oral rotavirus vaccine efficacy observed in children in developing countries. This study aimed to investigate the effect of rotavirus specific maternal antibodies on the serum IgA response or stool excretion of vaccine virus after any dose of an oral neonatal rotavirus vaccine, RV3-BB, in parallel to a Phase IIa clinical trial conducted at Dunedin Hospital, New Zealand. Methods: Rotavirus specific IgG and serum neutralizing antibody (SNA) levels in cord blood and IgA levels in colostrum and breast milk samples collected ~4 weeks, ~20 weeks and ~28 weeks after birth were measured. Infants were randomised to receive the first dose of vaccine at 0–5 days after birth (neonatal schedule) or at 8 weeks (infant schedule). Breast feeding was with-held for 30 minutes before and after vaccine administration. Data for IgA response and stool vaccine virus excretion after RV3-BB rotavirus vaccine was obtained from the Phase IIa clinical trial. The relationship between rotavirus specific IgA in colostrum or breast milk at the time of first active dose of RV3-BB vaccine and rotavirus specific IgG and SNA levels in cord blood, and level of IgA response and stool vaccine virus excretion after three doses of vaccine was assessed using linear and logistic regression. The relationship between rotavirus specific IgA in colostrum and rotavirus specific IgG a nd SNA levels in cord blood, and level of IgA response and stool vaccine virus excretion after a single neonatal dose of vaccine in the neonatal schedule group was also assessed. Results: Twenty one infants in the neonatal schedule group and 19 infants in the infant schedule group received 3 doses of RV3-BB rotavirus vaccine and were included in the analysis. Rotavirus specific IgA in colostrum and breast milk at 4 weeks was identified in 14/21 (67%) and 14/17 (82%) of infants in the neonatal and infant schedule groups respectively. IgA responses after 3 doses were identified in 76% and 74% of infants in the neonatal and infant groups, stool excretion of vaccine virus in 71% and 79% of infants. There was no evidence of an association between IgA in colostrum or breast milk IgA at 4 weeks and IgA response or stool excretion after three doses of RV3-BB, or after one dose (neonatal schedule). There was little evidence of an association between cord IgG or SNA level and level of IgA response and stool excretion after one neonatal dose or after 3 doses of RV3-BB. Conclusions: The level of IgA in colostrum or breast milk and placental IgG and SNA did not affect the serum IgA response or stool excretion following three doses of RV3-BB Rotavirus Vaccine administered using a neonatal or infant schedule in New Zealand infants

Leveque-Type Similarity Transformation for a Thermally Developing Viscous Dissipative Flow in a Parallel Plate Channel

Compared to the existing more elaborate eigenvalues-eigenfunction analytical solution where the solution of a thermally developing forced convection problem converges very slowly at the beginning of thermal entrant region, Leveque-type similarity transformation method provides a more convenient way to look into the insights of the problem. Assuming that the wall heat flux and viscous dissipation only has an effect within the thin thermal boundary layer at the beginning of the thermal entrance region, this study intends to solve the governing thermal energy equation for a thermally developing flow in a parallel plate channel, subjected to uniform heat flux, by means of Leveque-type similarity transformation. The resulting ordinary differential equation, is subsequently solved by a fourth order Runge Kutta method. A comparison of the Nusselt number along the axial direction, at the beginning of the thermally developing region with the literature, reveals less than 10% discrepancy for Brinkman number less than one, which is a commonly acceptable range for practical applications. Although its accuracy depletes downstream the channel, similarity transformation provides sufficiently accurate temperature distribution, and captures the heat transfer insights for a thermally developing viscous dissipative forced convection

Performance enhancement of subcooled flow boiling on graphene nanostructured surfaces with tunable wettability

Modifying the surface wettability at the solid-liquid interface can significantly improve flow boiling heat transfer. The graphene nanoplatelets (GNPs) and epoxy additives form nanocomposites coatings with tunable wettability (superhydrophilic, superhydrophobic and hydrophobic) via a thermal curing process. They are applied for enhancing the subcooled flow boiling heat transfer in a minichannel. By comparing with the uncoated surface, the superhydrophilic GNPs coating shows the highest boiling heat transfer coefficient with a maximum enhancement of 64.9 %. The nanocapillary-networks of the superhydrophilic GNPs coatings facilitate the fast water permeation effect and induce an effective filmwise boiling heat transfer. Moreover, the superhydrophilic GNPs coatings facilitate bubble detachment process and suppress the formation of dry spot during the boiling process. On the contrary, the hydrophobic and superhydrophobic GNPs coatings act as impervious blankets for the intercalation of water and deteriorate the flow boiling rates. The effects of the subcooled degree and the mass flux of the bulk flow on the performance enhancement are also investigated. This study aims to investigate the flow boiling enhancement attributed to the graphene functionalized coatings and provides interesting insights of the ultrafast water permeation mechanism of graphene into the subcooled flow boiling heat transfer

Entropy generation analysis of turbulent convection in a heat exchanger with self-rotating turbulator inserts

Turbulator inserts are commonly applied to enhance the thermal performance of heat exchangers with an accompanying rise in pressure drop due to the generation of the secondary swirl flow. We study the effect of inter-turbulator distance of rotating turbulator inserts on the heat transfer enhancement and entropy generation of forced convection in the turbulent flow region of a heat exchanger. Attributed to the turbulator inserts, the maximum rise of Nusselt number is 360% and 240%, for non-rotating and rotating cases, respectively, while the friction factor is increased significantly in the flow disturbed by the turbulator inserts. The Nusselt number and friction factor are augmented as the inter-turbulator distance is reduced. The partitioning of tube by the turbulator insert induces the swirl flow that leads to the enhancement of forced convection. From the second-law analysis, the entropy generation rate of the non-rotating case increases up to 202% comparing to that of the rotating case. This shows that the rotating turbulator insert is a more thermodynamically advantageous configuration, as it enhances the thermal performance appreciably while reducing the entropy generation significantly

Effects of silver epoxy reinforcement on graphene nanoplatelets functionalized surface in pool boiling heat transfer enhancement

Silver Epoxy reinforcement is pivotal to enhance the adhesive strength of Graphene nanoplatelets (GNP) on the substrate. This experimental study seeks to scrutinize the effects of Silver Epoxy reinforced GNP functionalized surface on the heat transfer of pool boiling. Three different GNP-based coatings are analyzed: simple GNP, uncured GNP reinforced with Silver Epoxy, and cured GNP reinforced with Silver Epoxy, all applied to copper substrate. For each coating, the surface morphology, chemical bonding, and wettability are examined. Under a heat flux of 550 kW/m2, the experimentally derived heat transfer coefficient improves by 194%, 36%, and 77% respectively on pristine GNP, uncured GNP/Epoxy, and cured GNP/Epoxy compared to the bare copper surface. The epoxy reinforcement weakens the exceptional boiling improvement achieved by a GNP functionalized surface. Although the thermal curing process turns the GNP/epoxy coating from hydrophobic to hydrophilic and recovers partly the level of boiling enhancement, the biphilicity of GNP tends to dominate boiling heat transfer enhancement by enhancing the bubble dynamics. The hydrophilicity has a subordinate effect by re-wetting the dry spots and preventing the vapour blanket. Silver Epoxy reinforcement significantly enhances the adhesive strength of GNP on a substrate but at the expense of boiling heat transfer enhancement

Anomalously enhanced subcooled flow boiling in superhydrophobic graphene-nanoplatelets-coated microchannels

In boiling heat transfer, superhydrophobic surface is deemed to reduce the critical heat flux (CHF) due to the immediate formation of an insulating vapor film that inhibits effective heat transfer despite its smaller energy barrier for bubble nucleation than that of a superhydrophilic surface. Here, a subcooled flow boiling investigation is carried out in a microchannel heat sink at a low mass flux condition using the superhydrophilic and superhydrophobic graphene nanoplatelets (GNPs) composite coatings. Interestingly, the flow boiling performance of the superhydrophobic GNPs-coated microchannel significantly transcends that of its superhydrophilic counterpart. By benchmarking with the performance of an uncoated microchannel, the CHF and heat transfer coefficient of the superhydrophobic GNPs-coated microchannel are enhanced up to 134% and 135%, respectively. This anomaly is ascribed to the Cassie Baxter-to-Wenzel transition on the superhydrophobic GNPs-coated surface, which is infiltrated with liquid, restricting the nucleating bubbles from expanding into a vapor film and sustaining an efficient boiling. The initial Wenzel state of the superhydrophobic GNPs surface is primarily ascribed to the rapid intercalation of water molecules via the unique graphene nanostructure. This study sheds new light on the unique wetting behavior of graphene-nanostructured surfaces in the context of microscale flow boiling heat transfer

Rotavirus specific maternal antibodies and immune response to RV3-BB neonatal rotavirus vaccine in New Zealand

Background: Maternal antibodies, acquired passively via placenta and/or breast milk, may contribute to the reduced efficacy of oral rotavirus vaccines observed in children in developing countries. This study aimed to investigate the effect of rotavirus specific maternal antibodies on the serum IgA response or stool excretion of vaccine virus after any dose of an oral rotavirus vaccine, RV3-BB, in parallel to a Phase IIa clinical trial conducted at Dunedin Hospital, New Zealand. At the time of the study rotavirus vaccines had not been introduced in New Zealand and the burden of rotavirus disease was evident. Methods: Rotavirus specific IgG and serum neutralizing antibody (SNA) levels in cord blood and IgA levels in colostrum and breast milk samples collected ∼4 weeks, ∼20 weeks and ∼28 weeks after birth were measured. Infants were randomized to receive the first dose of vaccine at 0–5 d (neonatal schedule) or 8 weeks (infant schedule). Breast feeding was with-held for 30 minutes before and after vaccine administration. The relationship between rotavirus specific IgG and SNA levels in cord blood and IgA in colostrum and breast milk at the time of first active dose of RV3-BB vaccine and level of IgA response and stool excretion after 3 doses of vaccine was assessed using linear and logistic regression. Results: Forty infants received 3 doses of RV3-BB rotavirus vaccine and were included in the analysis of the neonatal and infant groups. Rotavirus specific IgA in colostrum (neonatal schedule group) and breast milk at 4 weeks (infant schedule group) was identified in 14/21 (67%) and 14/17 (82%) of infants respectively. There was little evidence of an association between IgA in colostrum or breast milk IgA at 4 weeks, or between cord IgG or SNA level, and IgA response or stool excretion after 3 doses of RV3-BB, or after one dose (neonatal schedule) (all p>0.05). Conclusions: The level of IgA in colostrum or breast milk and level of placental IgG and SNA did not impact on the serum IgA response or stool excretion following 3 doses of RV3-BB Rotavirus Vaccine administered using either a neonatal or infant schedule in New Zealand infants