Shock induced aerobreakup of a droplet Sharma, Shubham; Pratap Singh, Awanish; Srinivas Rao, S. ...
Journal of fluid mechanics,
12/2021, Letnik:
929
Journal Article
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The multiscale dynamics of a shock–droplet interaction is crucial in understanding the atomisation of droplets due to external airflow. The interaction phenomena are classified into wave dynamics ...(stage I) and droplet breakup dynamics (stage II). Stage I involves the formation of different wave structures after an incident shock impacts the droplet surface. These waves momentarily change the droplet's ambient conditions, while in later times they are mainly influenced by shock-induced airflow. Stage II involves induced airflow interaction with the droplet that leads to its deformation and breakup. Primarily, two modes of droplet breakup, i.e. shear-induced entrainment and Rayleigh–Taylor piercing (RTP) (based on the modes of surface instabilities) were observed for the studied range of Weber numbers $(We\sim 30\text{--}15\,000)$. A criterion for the transition between two breakup modes is obtained, which successfully explains the observation of RTP mode of droplet breakup at high Weber numbers $(We\sim 800)$. For $We > 1000$, the breakup dynamics is governed by the shear-induced surface waves. After formation, the Kelvin–Helmholtz waves travel on the droplet surface and merge to form a liquid sheet near the droplet equator. Henceforth, the liquid sheet undergoes breakup processes via nucleation of several holes. The breakup process is recurrent until the complete droplet disintegrates or external drag acting on the droplet is insufficient for further disintegration. At lower Weber numbers, the droplet undergoes complete deformation like a flattened disk, and a multibag mode of breakup based on RTP is observed.
The health of the ocular surface is vital for clear vision and comfort. Various factors can adversely influence the ocular surface and tear film homeostasis, and these include procedures like ...cataract and corneal refractive surgery. It is, therefore, important to assess the integrity of the ocular surface in a rapid, predictable, and consistent manner in the clinic. Various tests and devices have been described, and while these are useful, this article highlights the importance of using fluorescein staining of the ocular surface in detecting changes. This is a simple, inexpensive, rapidly performed test that is available in most eye clinics. However, a proper technique of dye instillation and assessment is important to recognize the changes that can occur. Once detected, these changes can be quantified, and the location and patterns can be used to diagnose the diseases that are present; these changes can also be used to monitor treatment outcomes and disease progression. The article discusses the technique, assessment, and interpretation of fluorescein staining of the ocular surface, along with the role of the two other vital dyes - rose bengal and lissamine green.
Epstein-Barr virus (EBV) represents a major global health problem. Though it is associated with infectious mononucleosis and ∼200,000 cancers annually worldwide, a vaccine is not available. The major ...target of immunity is EBV glycoprotein 350/220 (gp350) that mediates attachment to B cells through complement receptor 2 (CR2/CD21). Here, we created self-assembling nanoparticles that displayed different domains of gp350 in a symmetric array. By focusing presentation of the CR2-binding domain on nanoparticles, potent neutralizing antibodies were elicited in mice and non-human primates. The structurally designed nanoparticle vaccine increased neutralization 10- to 100-fold compared to soluble gp350 by targeting a functionally conserved site of vulnerability, improving vaccine-induced protection in a mouse model. This rational approach to EBV vaccine design elicited potent neutralizing antibody responses by arrayed presentation of a conserved viral entry domain, a strategy that can be applied to other viruses.
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•Self-assembling nanoparticles present the conserved gp350 receptor-binding domain•The nanoparticles elicit more potent neutralizing antibodies than soluble gp350•These neutralizing antibodies predominantly target the CR2-binding site on gp350•The nanoparticles elicit potent neutralizing antibodies in mice and non-human primates
Structurally designed EBV vaccine candidates based on self-assembling nanoparticles elicit potent and durable virus-neutralizing antibodies that target the receptor-binding site on the viral envelope protein gp350, a site of vulnerability, serving as a template to develop an EBV vaccine and providing a basis for immunofocusing through rational vaccine design.
The paper presents a new design of a CP JLTFET, which is a type of transistor with potential applications in various electronic devices. The proposed CP JLTFET design is aimed at improving the ON ...current and surface potentials of the device. These improvements are essential for enhancing the device’s functionality. The source and drain regions in the intrinsic silicon material are induced using appropriate metal work functions. This design choice is made for ease of fabrication, which is a critical consideration in semiconductor device manufacturing. The cavity length is varied between 8 and 10 nm, and different dielectric constants are used in the simulation. These variations are designed to optimize the ON state performance of the device, including ON drive current, potential, and electric field. The increase in tunneling of electrons is attributed to high carrier recombination in the channel region. Carrier recombination is a key factor in device behavior and performance. The paper describes the simulation of various electrical parameters of the proposed device. This likely includes drain current, surface potentials, electric field, and energy bands. The excellent performance parameters of the proposed device, when combined with appropriate materials and the introduction of a cavity, make it suitable for sensing applications of biomolecules. The paper suggests that the excellent performance parameters of the proposed device, when combined with appropriate materials and the introduction of a cavity in the device, make it suitable for sensing applications, particularly for detecting biomolecules.
Agriculture has been considered as one of the contributors to greenhouse gas (GHG) emissions and it continues to increase with increase in crop production. Hence development of sustainable agro ...techniques with maximum crop production, and low global warming potential is need of the hour. Quantifying net global warming potential (NGWP) and greenhouse gas intensity (GHGI) of an agricultural activity is a method to assess the mitigation potential of the activity. But there is dearth of information on NGWP of conservation agriculture under rainfed conditions. Hence in this study two methods such as crop based (NGWPcrop) and soil based (NGWPsoil) were estimated from the data of the experiment initiated in 2009 in rainfed semiarid regions of Hyderabad, India with different tillage practices like conventional tillage (CT), reduced tillage (RT), zero tillage (ZT) and residue retention levels by harvesting at different heights which includes 0, 10 and 30 cm anchored residue in pigeonpea-castor systems. The results of the study revealed that under rainfed conditions CT recorded 24% higher yields over ZT, but CT and RT were on par with each other. However, the yield gap between the tillage treatments is narrowing down over 5 years of study. ZT and RT recorded 26 and 11% lower indirect GHG emissions (emissions from farm operations and input use) over CT, respectively. The percent contribution of CO2 eq. N2O emission is higher to total GHG emissions in both the crops. Both NGWPcrop, NGWPsoil, GHGIcrop, and GHGIsoil based were influenced by tillage and residue treatments. Further, castor grown on pigeonpea residue recorded 20% higher GHG emissions over pigeonpea grown on castor residues. The fuel consumption in ZT was reduced by 58% and 81% as compared to CT in pigeonpea and castor, respectively. Lower NGWP and GHGI based on crop and soil was observed with increase in crop residues and decrease in tillage intensity in both the crops. The results of the study indicate that, there is scope to reduce the NGWP emissions by reducing one tillage operation as in RT and increase in crop residue by harvesting at 10 and 30 cm height with minimal impact on the crop yields. However, the trade-off between higher yield and soil health versus GHG emissions should be considered while promoting conservation agriculture. The NGWPcrop estimation method indicated considerable benefits of residues to the soil and higher potential of GHG mitigation than by the NGWPsoil method and may overestimate the potential of GHG mitigation in agriculture system.
•CT recorded 24% higher yields over ZT but CT and RT were on par with each other.•Contribution of N2O based CO2 emissions were higher to total GHG emissions in pigeonpea and castor.•Two approaches NGWP crop and NGWP soil were used to estimate the GWP but they produced contradictory results.•Lower NGWP and GHGI was observed with increase in crop residues and decrease in tillage intensity.•The results depended largely on the method used.
To protect against human immunodeficiency virus (HIV-1) infection, broadly neutralizing antibodies (bnAbs) must be active at the portals of viral entry in the gastrointestinal or cervicovaginal ...tracts. The localization and persistence of antibodies at these sites is influenced by the neonatal Fc receptor (FcRn), whose role in protecting against infection in vivo has not been defined. Here, we show that a bnAb with enhanced FcRn binding has increased gut mucosal tissue localization, which improves protection against lentiviral infection in non-human primates. A bnAb directed to the CD4-binding site of the HIV-1 envelope (Env) protein (denoted VRC01) was modified by site-directed mutagenesis to increase its binding affinity for FcRn. This enhanced FcRn-binding mutant bnAb, denoted VRC01-LS, displayed increased transcytosis across human FcRn-expressing cellular monolayers in vitro while retaining FcγRIIIa binding and function, including antibody-dependent cell-mediated cytotoxicity (ADCC) activity, at levels similar to VRC01 (the wild type). VRC01-LS had a threefold longer serum half-life than VRC01 in non-human primates and persisted in the rectal mucosa even when it was no longer detectable in the serum. Notably, VRC01-LS mediated protection superior to that afforded by VRC01 against intrarectal infection with simian-human immunodeficiency virus (SHIV). These findings suggest that modification of FcRn binding provides a mechanism not only to increase serum half-life but also to enhance mucosal localization that confers immune protection. Mutations that enhance FcRn function could therefore increase the potency and durability of passive immunization strategies to prevent HIV-1 infection.
Influenza viruses pose a significant threat to the public and are a burden on global health systems. Each year, influenza vaccines must be rapidly produced to match circulating viruses, a process ...constrained by dated technology and vulnerable to unexpected strains emerging from humans and animal reservoirs. Here we use knowledge of protein structure to design self-assembling nanoparticles that elicit broader and more potent immunity than traditional influenza vaccines. The viral haemagglutinin was genetically fused to ferritin, a protein that naturally forms nanoparticles composed of 24 identical polypeptides. Haemagglutinin was inserted at the interface of adjacent subunits so that it spontaneously assembled and generated eight trimeric viral spikes on its surface. Immunization with this influenza nanoparticle vaccine elicited haemagglutination inhibition antibody titres more than tenfold higher than those from the licensed inactivated vaccine. Furthermore, it elicited neutralizing antibodies to two highly conserved vulnerable haemagglutinin structures that are targets of universal vaccines: the stem and the receptor binding site on the head. Antibodies elicited by a 1999 haemagglutinin-nanoparticle vaccine neutralized H1N1 viruses from 1934 to 2007 and protected ferrets from an unmatched 2007 H1N1 virus challenge. This structure-based, self-assembling synthetic nanoparticle vaccine improves the potency and breadth of influenza virus immunity, and it provides a foundation for building broader vaccine protection against emerging influenza viruses and other pathogens.
The antibody response to influenza is primarily focused on the head region of the hemagglutinin (HA) glycoprotein, which in turn undergoes antigenic drift, thus necessitating annual updates of ...influenza vaccines. In contrast, the immunogenically subdominant stem region of HA is highly conserved and recognized by antibodies capable of binding multiple HA subtypes. Here we report the structure-based development of an H1 HA stem-only immunogen that confers heterosubtypic protection in mice and ferrets. Six iterative cycles of structure-based design (Gen1-Gen6) yielded successive H1 HA stabilized-stem (HA-SS) immunogens that lack the immunodominant head domain. Antigenic characterization, determination of two HA-SS crystal structures in complex with stem-specific monoclonal antibodies and cryo-electron microscopy analysis of HA-SS on ferritin nanoparticles (H1-SS-np) confirmed the preservation of key structural elements. Vaccination of mice and ferrets with H1-SS-np elicited broadly cross-reactive antibodies that completely protected mice and partially protected ferrets against lethal heterosubtypic H5N1 influenza virus challenge despite the absence of detectable H5N1 neutralizing activity in vitro. Passive transfer of immunoglobulin from H1-SS-np-immunized mice to naive mice conferred protection against H5N1 challenge, indicating that vaccine-elicited HA stem-specific antibodies can protect against diverse group 1 influenza strains.
Three-dimensional reconstructions of thermal field in a differentially heated cylindrical cavity with dilute concentrations of nanofluids as the working medium have been reported. Experiments have ...been conducted in a specially designed tomography cell filled with dilute concentrations of Al
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nanofluids with ethylene glycol dimethacrylate (EGD) as the basefluid. The two horizontal walls of the cell have been differentially heated to apply the temperature potential across the fluid layer. Multiple projection data in the form of interferometric images have been recorded at every 20° view angle by slowly turning the cell over the range of 0 to 360°. The two-dimensional temperature fields retrieved through the quantitative analysis of interferometric images recorded at various view angles have been used to reconstruct the complete three-dimensional temperature field at select horizontal planes of the fluid layer. Iterative multiplicative algebraic reconstruction technique (MART) has been employed for tomography reconstructions. Based on the tomography reconstructions, possible fluid movement in the test cavity and the strong dependence of convective field on varying nanofluid concentrations and cavity temperature differences have been explained. Distribution of local temperature fields near the cavity wall surfaces revealed the phenomena of breakdown of large length scale fluid structures into multiple roll-like patterns with increasing concentration of nanoparticles. The distribution of the local Nusselt number, on select horizontal planes near the top and bottom wall surfaces of the cavity, highlighted the possible role of nanoparticles enhancing the heat transfer rates. An overall energy balance in the cavity was also to be seen based on the reconstructions of the local profiles of Nusselt numbers.
Electromagnetic (EM) brakes are gaining importance in aerospace vehicles for various critical applications. In guided missiles, they are primarily used for locking the actuator when the missile is in ...carriage either by road or by air such that the position of the actuator is not changed when servo is in the off condition. In this paper, a new EM brake is designed which is more energy efficient and reliable compared to a conventional solenoid operated brake. The nonlinear magnetic analysis is carried out on the brake, and the hardware is realized and tested. The test results are promising and this topology can be adapted for aerospace and other critical applications.
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