The enhancement of laminar jet cooling effectiveness at very high surface temperature by using Al2O3 nanofluid as a coolant

In the current study, as per the requirement of various metal quenching industries, high heat removal rate, low consumption rate of the coolant, and the minimum operating cost of the process have been tried to be achieved in the Leidenfrost region by using a nanofluid low mass flux laminar jet. In this regard, an indigenously designed and fabricated experimental setup was used and before experimentation, the coolant (Al₂O₃+Water) thermophysical properties variation was monitored for the mapping of the transfer characteristics during the cooling process. The thermal analysis discloses that the critical heat flux (CHF) depicts a trend with the rising nanoparticle concentration in the mixture; however, at the medium concentration (0.10% Al₂O₃) except the CHF region, in the remaining region, better heat removal rate is observed. The comparison of the current cooling methodology with that reported in literature clearly approves that the proposed process methodology mitigates the requirements described above.     

Domestic use of dirty energy and its effects on human health: empirical evidence from Bhutan

Use of dirty fuels such as fuelwood, charcoal, cow dung and kerosene is common in developing countries, which adversely affects the health of people living in the dwellings, especially children and women. Using the data from a comprehensive and nationally representative Bhutan Living Standard Survey 2012, the present study examines the effects of dirty fuels on human health and household health expenditure. The result from propensity score-matching approach indicate that households using dirty fuels have a higher incidence of respiratory disease by 2.5–3% compared to households using cleaner fuels. The chances of household contracting tuberculosis are higher for households using dirty fuel in the range of 5–6%. It is also observed that the incidence of eye diseases and health expenditures among households using dirty fuels is higher. Hence the policy should focus on providing access to clean sources of energy to wider population.     

A Novel Multi-agent Formation Control Law With Collision Avoidance

In this paper a stable formation control law that simultaneously ensures collision avoidance has been proposed. It is assumed that the communication graph is undirected and connected. The proposed formation control law is a combination of the consensus term and the collision avoidance term (CAT). The first order consensus term is derived for the proposed model, while ensuring the Lyapunov stability. The consensus term creates and maintains the desired formation shape, while the CAT avoids the collision. During the collision avoidance, the potential function based CAT makes the agents repel from each other. This unrestricted repelling magnitude cannot ensure the graph connectivity at the time of collision avoidance. Hence we have proposed a formation control law, which ensures this connectivity even during the collision avoidance. This is achieved by the proposed novel adaptive potential function. The potential function adapts itself, with the online tuning of the critical variable associated with it. The tuning has been done based on the lower bound of the critical variable, which is derived from the proposed connectivity property. The efficacy of the proposed scheme has been validated using simulations done based on formations of six and thirty-two agents respectively.      

Effect of Artificial Defects on Electric and Magnetic Transport Properties in YBa2Cu3O7−δ Thick Film

The effect of 200 MeV Ag ions on YBa₂Cu₃O_7?δ /5 wt.% Y₂O₃ composite thick films is studied. The structural deformity is analysed with X-ray diffraction showing reduced peak intensity. The decrease of transition temperature as a function of ion fluence has been observed from temperature-dependent resistivity and magnetization measurement. Fluctuation conductivity studied within the framework of Aslamazov–Larkin and Lawrence–Doniach theories fits well for 3D and 2D regimes with the appearance of critical region beyond 3D regime. Pseudogap temperature estimated above 100 K shifts to lower temperature zone as a function of ion doses. We report an enhancement of critical current density and flux pinning due to dual impact of swift heavy ion and Y₂O₃ inclusions at isothermal temperatures 40 K and 60 K.     

Gelatin–PEG based metronidazole-loaded vaginal delivery systems: preparation,characterization and in vitro antimicrobial efficiency

Bacterial vaginosis (BV) is a condition often associated with the overgrowth of pathogenic microbes with a subsequent decrease in lactic acid producing bacteria in vagina. BV is predominant in reproductive women. It has been reported not only to cause pre-term labor but is also one of the major causes of fetal morbidity and mortality. There is an increase in the vaginal discharge in BV. Due to this reason, the locally applied drug formulations are quickly washed off. It is expected that the mucoadhesive delivery vehicles will improve the bioavailability of the drug for prolonged periods. Keeping this in mind, gelatin/PEG based composite hydrogels were developed and characterized as vaginal delivery systems for the treatment of BV. The hydrogels were prepared by varying the concentration of gelatin and PEG. The hydrogels were thoroughly characterized using SEM, FTIR, DSC, and impedance spectroscopy techniques and swelling, mucoadhesive, and texture analysis studies. The in vitro release behavior of metronidazole from the hydrogels was analyzed in-depth. The antimicrobial efficiency of the MZ-loaded hydrogels was tested against E. coli, occurrence of which is predominant in BV. The properties of the hydrogels were found to be dependent on the composition of the hydrogels. The hydrogels were found to be mucoadhesive and the MZ-loaded hydrogels have shown effective antimicrobial activity against E. coli. Based on the preliminary studies, the composite hydrogels were found to be suitable for controlled drug delivery for vaginal applications.     

Analysis of factors influencing deflection in sandwich panels subjected to low-velocity impact

Fiber reinforced sandwich structures typically respond very poorly to transverse impact events. This paper is an attempt to investigate the impact response of sandwich panels subjected to low-velocity impact. Experimental investigations were carried out on the influence of three design factors: height of fall, core thickness, and impactor mass, which are the most relevant parameters to be considered for deflection. The study of behavior of the mentioned response was done by using Design of Experiments tool. Response surface methodology (RSM), a sequential experimentation strategy for model building, is used to model the response in order to determine the most significant factor among the influential factors. In this case, full factorial face-centered central composite design was chosen due to the number of factors and their levels in the study. The specimen consisted of face sheets made up of bi-woven glass fiber cloth with polyurethane foam as core material. The parametric analysis reveals that deflection increases steadily with an increase in the height of fall when compared with the impactor mass and the core thickness. The reason for this study is imperative for the next generation aircraft, marine, road, and rail vehicles with improved lightweight stiff materials that can absorb higher impact energy with higher resistance to deflection.     

Enhancement of Flux Pinning in YBa2Cu3O7−δ + Ag Nanocomposites

YBa₂Cu₃O_7?δ /Ag thin film is prepared through pulsed laser deposition. The presence of Ag brings about significant inter- and intragranular modification in the microstructure of the composites. The resistive broadening in the tail part is suggested to be associated with the link between the grains and to be extremely sensitive to magnetic fields. It is assumed that the zero resistance state at the T _c0 region of the above high temperature superconductor is governed by the excitations in the weak link network. Invoking Beans critical state model, enhancement in critical current density J _c is observed.     

Rapid response oxygen-sensing nanofibers

Molecular oxygen has profound effects on cell and tissue viability. Relevant sensor forms that can rapidly determine dissolved oxygen levels under biologically relevant conditions provide critical metabolic information. Using 0.5 μm diameter electrospun polycaprolactone (PCL) fiber containing an oxygen-sensitive probe, tris (4,7-diphenyl-1,10-phenanthroline) ruthenium(II) dichloride, we observed a response time of 0.9 ± 0.12 s while the t₉₅ for the corresponding film was more than two orders of magnitude greater. Interestingly, the response and recovery times of slightly larger diameter PCL fibers were 1.79 ± 0.23 s and 2.29 ± 0.13 s, respectively, while the recovery time was not statistically different likely due to the more limited interactions of nitrogen with the polymer matrix. A more than 10-fold increase in PCL fiber diameter reduces oxygen sensitivity while having minor effects on response time; conversely, decreases in fiber diameter to less than 0.5 μm would likely decrease response times even further. In addition, a 50 °C heat treatment of the electrospun fiber resulted in both increased Stern–Volmer slope and linearity likely due to secondary recrystallization that further homogenized the probe microenvironment. At exposure times up to 3600 s in length, photobleaching was observed but was largely eliminated by the use of either polyethersulfone (PES) or a PES–PCL core–shell composition. However, this resulted in 2- and 3-fold slower response times. Finally, even the non-core shell compositions containing the Ru oxygen probe result in no apparent cytotoxicity in representative glioblastoma cell populations.