Depinning of liquid droplets on substrates by flow of a surrounding immiscible fluid is central to applications such as cross-flow microemulsification, oil recovery and waste cleanup. Surface roughness, either natural or engineered, can cause droplet pinning, so it is of both fundamental and practical interest to determine the flow strength of the surrounding fluid required for droplet depinning on rough substrates. Here, we develop a lubrication-theory-based model for droplet depinning on a substrate with topographical defects by flow of a surrounding immiscible fluid. The droplet and surrounding fluid are in a rectangular channel, a pressure gradient is imposed to drive flow and the defects are modelled as Gaussian-shaped bumps. Using a precursor-film/disjoining-pressure approach to capture contact-line motion, a nonlinear evolution equation is derived describing the droplet thickness as a function of distance along the channel and time. Numerical solutions of the evolution equation are used to investigate how the critical pressure gradient for droplet depinning depends on the viscosity ratio, surface wettability and droplet volume. Simple analytical models are able to account for many of the features observed in the numerical simulations. The influence of defect height is also investigated, and it is found that, when the maximum defect slope is larger than the receding contact angle of the droplet, smaller residual droplets are left behind at the defect after the original droplet depins and slides away. The model presented here yields considerably more information than commonly used models based on simple force balances, and provides a framework that can readily be extended to study more complicated situations involving chemical heterogeneity and three-dimensional effects.

Circular antenna array (CAA) is one of the most widely used antenna array designs. This paper addresses the design challenges of the CAA with the non-uniform single ring, which is placed in an X-Y plane with the best sidelobe level (SLL) and improved first null beamwidth (FNBW). It has been solved using differential evolution, craziness-based particle swarm optimization (CRPSO), and novel particle swarm optimization (NPSO) techniques. An optimal combination of feeding current and inter-element spacing provides an array pattern with the best SLL and improved FNBW, as well as some other parameter calculations of the antenna array like maximum directivity, maximum effective aperture, total effective aperture, maximum beam area, total beam area, circumference, and radius of the CAAs using these techniques. There are six designs of CAAs with different antenna elements (i.e., 10-, 12-, 16-, 20-, 36-, and 64-elements) which have been taken into account. Simulations are done in MATLAB. Based on various simulation results, we can analyze the performance of SLL and FNBW with other parameters using NPSO and compare them with different techniques of CAAs, as shown in the numerical analysis and simulation result section.

Evaporating sessile droplets are critical to many industrial applications and are also ubiquitous in nature. Two predominant evaporation models have emerged in the literature, one-sided and diffusion-limited, with differing assumptions on the evaporation process. Both models are used widely, and their predictions can differ greatly from each other, but the physical mechanisms responsible for these differences are not yet well understood. Here, we develop a lubrication-theory-based model of a thin evaporating sessile droplet, and compare predictions from both evaporation models to elucidate the origins of the differences in their predictions. For the one-sided model, we derive expressions for the droplet lifetime, show that in certain parameter regimes the total evaporation rate is proportional to the droplet surface area, and demonstrate that the contact line is always warmer than the bulk of the droplet. Furthermore, we show that differences in the structures of the evaporation models near the contact line lead to qualitatively different behaviour of the apparent contact angles and interface temperature profiles. The fundamental understanding gained from this work is expected to be helpful in determining which evaporation model is most appropriate for describing experimental observations.

In July 2021, Liverpool was removed from the prestigious List of World Heritage Sites, sending shockwaves around the global heritage community. More recently, the spotlight has shifted to another world famous site also located in the United Kingdom. During the same 44th Session of the World Heritage Committee, UNESCO threatened to place Stonehenge on the List in Danger if the required changes to a significant billion-pound road enhancement project were not implemented. Given what happened in Liverpool, there are fears that Stonehenge is in danger of moving towards delisting. An interesting critical line of inquiry to emerge from Liverpool, and other World Heritage Sites, concerns the local, national, and international ‘politics at the site’. This article develops this debate by analysing the role of different scalar actors involved in the Stonehenge World Heritage Site. More specifically, our article examines how the Stonehenge Alliance sought to engage in, what we define as, scalar manoeuvres that is evidenced by scale jumping and scalar alignments with more powerful players further up the heritage hierarchy in order to effect leverage over the future status of the World Heritage Site.

The temperature of maximum pyrolysis yield (known as Tmax) can be used to determine the level of thermal alteration in sedimentary organic matter; higher Tmax values represent higher thermal alteration. Tmax is commonly measured on petroleum source rocks or similar sediments with high organic carbon contents. It would be desirable to measure the Tmax of volcanic sediments because they can have complex patterns of thermal alteration. However, volcanic sediments often have low total organic carbon contents and consequently are susceptible to analytical interferences. Despite this, it can be shown that meaningful Tmax measurements can still be made in sediment with organic carbon contents as low as 0.2% and that interference caused by bitumen or ionizable salts can be mitigated by solvent extraction and rinsing with water. Thus, it is reasonable to use temperature programmed pyrolysis to assess levels of thermal alteration in even low total organic carbon volcanoclastic sediments.

Partially wetting droplets under an airflow can exhibit complex behaviours that arise from the coupling of surface tension, inertia of the external flow and contact-line dynamics. Recent experiments by Hooshanginejad et al. (J. Fluid Mech., vol. 901, 2020) revealed that a millimetric partially wetting water droplet under an impinging jet can oscillate in place, split or depin away from the jet, depending on the magnitude (i.e. $5\unicode{x2013}20\ {\rm m}\ {\rm s}^{-1}$) and position of the jet. To rationalise the experimental observations, we develop a two-dimensional lubrication model of the droplet that incorporates the external pressure of the impinging high-Reynolds-number jet, in addition to the capillary and hydrostatic pressures of the droplet. Distinct from the previous model by Hooshanginejad et al. (J. Fluid Mech., vol. 901, 2020), we simulate the motion of the contact line using precursor film and disjoining pressure, which allows us to capture a wider range of droplet behaviours, including the droplet dislodging to one side. Our simulations exhibit a comparable time-scale of droplet deformations and similar outcomes as the experimental observations. We also obtain the analytical steady-state solutions of the droplet shapes and construct the minimum criteria for splitting and depinning.

Capillary flow of liquids plays a key role in many applications including lab-on-a-chip devices, heat pipes and printed electronics manufacturing. Open rectangular microchannels often appear in these applications, with the lack of a top resulting in a complex free-surface morphology and evaporation. In this work we develop a theoretical model based on lubrication theory and kinetically limited evaporation to examine capillary flow of evaporating liquid solutions in open rectangular microchannels connected to circular reservoirs. The model accounts for the complex free-surface morphology, solvent evaporation, Marangoni flows due to gradients in solute concentration and temperature and finite-size reservoir effects. Significant differences are predicted in flow behaviour between pure liquids and liquid solutions due to solvent evaporation and solute transport. Marangoni flows are found to promote more uniform solute deposition patterns after solvent evaporation. Model predictions of meniscus position evolution are in good agreement with prior capillary-flow experiments of aqueous poly(vinyl alcohol) solutions in the presence of evaporation. The model reveals that the principal mechanism through which evaporation influences the meniscus position in the experiments is the increase in viscosity with solute concentration.

The study was undertaken to examine the relative abundance (RA) of the major developmental important candidate genes in different grades of immature oocytes (A-grade, B-grade, C-grade and D-grade) and various stages of in vitro-produced embryos (2-cell, 4-cell, 8–16-cell, morula, and blastocyst) of buffalo using RT-qPCR. Results showed that the RA of GLUT1, CX43, HSP70.1 and GDF9 was significantly higher (P < 0.05) in the A-grade of oocytes than the C-grade and D-grade but did not differ significantly from the B-grade of oocytes. Similarly, RA of BMP15 and Survivin were significantly higher (P < 0.05) in A-grade than the other grades of oocytes, however, poly(A) polymerase expression was not significantly different (P > 0.05) among the immature oocytes. The expression of GLUT1 was significantly higher (P < 0.05) in the blastocysts, but the expression of CX43 (P < 0.05; P > 0.05), HSP70.1 (P < 0.05; P > 0.05) and GDF9 (P > 0.05) was higher at the 2-cell stage than the other stages of embryos. Interestingly, the expression levels of poly(A) polymerase (P < 0.05), BMP15 (P < 0.05; P > 0.05) and Survivin (P > 0.05) were higher at the 8–16-cell stage than the other stages of embryos. It is concluded that A-grade of immature oocytes has shown more mRNA abundance for the major developmental important genes; therefore A-grade oocytes may be considered as the most developmentally competent and suitable for handmade cloning research in buffalo.

The coating of rotating discrete objects with surface topography is a problem commonly encountered in manufacturing processes. Surface topography may induce undesired disturbances in the coating, leading to coatings of non-uniform thickness. To study this problem, we model the flow of thin liquid coatings in three dimensions on topographically patterned cylinders that rotate about their horizontal axes. An evolution equation describing variations in the coating thickness as a function of the axial coordinate, the angular coordinate, and time is solved numerically using a variable time-step finite-difference scheme. In the limit of a rapidly rotating cylinder, we neglect the effects of gravity and find that liquid accumulates at either pattern crests or pattern troughs. Using a long-wave analysis, we derive an expression for the critical Weber number that separates these regimes. If gravity is reincorporated, the accumulation of liquid at crests or troughs may cause the coating to sag under its weight, leading to the formation of droplets or rings whose spacing at large rotation rates is controlled by the balance between centrifugal and surface-tension forces. At lower rotation rates, where gravitational forces dominate, simulation results indicate that cylinder topography tends to alter the rate at which droplets form, but does not necessarily systematically affect the spacing between droplets. Flow visualization experiments yield results that agree quantitatively with predictions of the simulations and long-wave analysis. We observe the most uniform coatings in experiments at moderate rotation rates, where disturbances in the coating thickness develop slowly. This indicates that to obtain nearly uniform coatings in practice, the coating must be solidified faster than disturbances can develop.

The present study was undertaken to analyze the relative abundance (RA) of pluripotency-associated genes (NANOG, OCT4, SOX2, c-MYC, and FOXD3) in different grades of immature oocytes and various stages of in vitro-produced buffalo embryos using RT-qPCR. Results showed that the RA of NANOG, OCT4, and FOXD3 transcripts was significantly higher (P < 0.05) in A grade oocytes compared with the other grades of oocytes. The RA of the c-MYC transcript was significantly higher (P < 0.05) in A grade compared with the C and D grades of oocytes, but the values did not differ significantly from the B grade of oocytes. The RA of the SOX2 transcript was almost similar in all grades of the oocytes. The expression levels of NANOG (P > 0.05), OCT4 (P > 0.05), c-MYC (P > 0.05) and SOX2 (P < 0.05) were higher in the blastocysts compared with the other stages of the embryos. Markedly, FOXD3 expression was significantly higher (P < 0.05) in 8–16-cell embryos compared with the 2-cell and 4-cell embryos and blastocyst, but did not differ significantly from the morula stage of the embryos. In the study, the majority of pluripotency-associated genes showed higher expression in A grade immature oocytes. Therefore, it is concluded that the A grade oocytes appeared to be more developmental competent and are suitable candidates for nuclear cloning research in buffalo. In buffalo, NANOG, OCT4, SOX2, and c-MYC are highly expressed in blastocysts compared with the other stages of embryos.

Spontaneous capillary flow of liquids in narrow spaces plays a key role in a plethora of applications including lab-on-a-chip devices, heat pipes, propellant management devices in spacecrafts and flexible printed electronics manufacturing. In this work we use a combination of theory and experiment to examine capillary-flow dynamics in open rectangular microchannels, which are often found in these applications. Scanning electron microscopy and profilometry are used to highlight the complexity of the free-surface morphology. We develop a self-similar lubrication-theory-based model accounting for this complexity and compare model predictions to those from the widely used modified Lucas–Washburn model, as well as experimental observations over a wide range of channel aspect ratios $\lambda$ and equilibrium contact angles $\theta _0$. We demonstrate that for large $\lambda$ the two model predictions are indistinguishable, whereas for smaller $\lambda$ the lubrication-theory-based model agrees better with experiments. The lubrication-theory-based model is also shown to have better agreement with experiments at smaller $\theta _0$, although as $\theta _0\rightarrow {\rm \pi}/4$ it fails to account for important axial curvature contributions to the free surface and the agreement worsens. Finally, we show that the lubrication-theory-based model also quantitatively predicts the dynamics of fingers that extend ahead of the meniscus. These findings elucidate the limitations of the modified Lucas–Washburn model and demonstrate the importance of accounting for the effects of complex free-surface morphology on capillary-flow dynamics in open rectangular microchannels.

Dynamic wetting failure in shear-thinning and shear-thickening liquids is examined in this paper. Flow visualization experiments using a curtain-coating geometry suggest that shear thinning postpones the onset of wetting failure and the resulting air entrainment. To advance the fundamental understanding of the underlying physical mechanisms, a hydrodynamic model consisting of liquid displacing air in a rectangular channel in the absence of inertia is developed. Both shear thinning and shear thickening are considered by using Carreau-type models to describe the liquid rheology. Steady-state solutions are calculated using the Galerkin finite-element method and the critical capillary number where wetting failure occurs is identified. Shear thinning is found to postpone the onset of wetting failure whereas shear thickening is found to promote it. The underlying mechanism involves thickening/thinning of the air film as a consequence of shear thinning/thickening of the liquid and the tangential stress balance. The results can be interpreted in terms of an effective viscosity, and demonstrate that similar physical mechanisms govern dynamic wetting failure in Newtonian, shear-thinning and shear-thickening liquids.

The photostability of two glycine molecules has been investigated using quantum mechanical methods i.e. at CASSCF/NEVPT2 level theory. It is found that the molecule in water shows vast photostability as a comparison to vacuum. The energies are calculated around HOMO and LUMO orbital. The NEVPT2 computed energies are reasonably matched with experimental results. The study shows that the molecule returns from higher electronically excited states to ground state through CI and AC crossings and these crossings provide a minimum energy path along derivative coupling and gradient differences vector.

Humite group minerals occur in the marbles of granulite grade at Ambasamudram, southern India. Detailed mineralogical and mineral chemical characterization indicate the mineral is a flourine-rich titanian-poor variety of clinohumite. Average MTi/Si values of 2.22 with typical XRD pattern indicate the mineral to be clinohumite. Petrological constraints on the clinohumite formation shows a high temperature (>700°C) and low aco2 during its formation. The fluorine content of these clinohumites is the highest reported in any environment, with F/(F+OH) ratio reaching a value of 0.70. The high fluorine content reflect the high P-T condition of formation. The OH content of the clinohumites is around 0.59 mole fraction. Preliminary FTIR spectra of the clinohumites show eight sharp absorption peaks between wave numbers 3700 and 3400 cm−1 and a broad absorption band with a peak at 3840 cm−1. The sharp peaks are due to OH in the clinohumite. The high fluorine content of the Ambasamudram clinohumites possibly resulted from the isochemical reactions involving (OH-F) silicates such as amphiboles or phlogopites. The internal fluid buffering is also supported by the stable isotope as well as the petrological studies of the marble assemblages.

Scheelite mineralization in the granulite-facies supracrustal sequences of the Kerala Khondalite Belt, southern India is reported. The supracrustal sequences where the mineralization is found comprise granulite-grade metasediments which underwent metamorphism at ∼550 Ma. The mineralization is assumed to have formed by late-stage metasomatism that overprinted the regional metamorphism of the country rock (garnet-biotite gneiss) and occurs along a quartz vein that intrudes the regional foliation. The paragenetic data from the vein demonstrate unambiguously a separate cycle of hydrothermal activity, resulting in metasomatism and mineralization. Scheelite is found in both the altered host rock along the foliation plane and in the quartz vein. Fluid inclusions preserved in the vein suggest that the mineralizing fluids were saline-aqueous in composition, while those in the country rocks were predominantly CO2-rich. The mineral chemistry and bulk-rock chemical composition of the mineralized domain reveal the unusual enrichment of Ca in the mineralised zone with the depletion of K. We propose that fluid discharging from a crystallizing deep-seated magma, mixing with deep circulating Ca-bearing palaeo-groundwater gave rise to the deposition of scheelite. The scheelite mineralization and the quartz vein emplacement occurred after the Pan-African regional metamorphism.

The coating of discrete objects is an important but poorly understood step in the manufacturing of a broad variety of products. An important model problem is the flow of a thin liquid film on a rotating cylinder, where instabilities can arise and compromise coating uniformity. In this work, we use lubrication theory and flow visualization experiments to study the influence of surfactant on these flows. Two coupled evolution equations describing the variation of film thickness and concentration of insoluble surfactant as a function of time, the angular coordinate and the axial coordinate are solved numerically. The results show that surface-tension forces arising from both axial and angular variations in the angular curvature drive flows in the axial direction that tend to smooth out free-surface perturbations and lead to a stable speed window in which axial perturbations do not grow. The presence of surfactant leads to Marangoni stresses that can cause the stable speed window to disappear by driving flow that opposes the stabilizing flow. In addition, Marangoni stresses tend to reduce the spacing between droplets that form at low rotation rates, and reduce the growth rate of rings that form at high rotation rates. Flow visualization experiments yield observations that are qualitatively consistent with predictions from linear stability analysis and the simulation results. The visualizations also indicate that surfactants tend to suppress dripping, slow the development of free-surface perturbations, and reduce the shifting and merging of rings and droplets, allowing more time for solidifying coatings in practical applications.

Solar rotation is still one of the unresolved concern of solar physics. We performed time series analysis on the bins formed on equally separated latitude regions on the soft X-ray images. These images are observed with the X-ray telescope (XRT) on board the Hinode satellite. The flux modulation method traces the passage of X-ray feature over the solar disc and statistical analysis of the time series data of the SXR images (one per day) for the period extends from year 2015 to 2017 gives the coronal rotation period as a function of latitude. The investigation provided quite systematic information of the solar rotation and its variability.

The protozoan parasite Leishmania is endemic in large parts of the world which causes leishmaniasis. Its visceral form is fatal if not treated and is caused mostly by Leishmania donovani, Leishmania infantum and Leishmania chagasi. Given the difficulties linked to vector (sandfly) control and the lack of an effective vaccine, the control of leishmaniasis relies mostly on chemotherapy. Unfortunately, the prevalence of parasites becoming resistant to the first-line drug pentavalent antimony (SbV) is increasing worldwide. Few alternative drugs are available that includes amphotericin B, pentamidine and miltefosine (oral). Already, decreases in efficacy, resistance and toxicity have been noted against these drugs. Dry antileishmanial pipeline further indicates the slow pace of drug discovery in this field where resistance as a major barrier. Full understanding of the genetic and molecular basis of the parasite is lagging. Since leishmaniasis is a neglected disease and occurs predominantly in the developing world largely, therefore, it is unaddressed. The pharma industry argues that development of the new drug is too costly and risky to invest in low return neglected diseases is very high. Research is also needed to identify new and effective drug targets. The lack of drug research and development for neglected diseases will require some new strategies. We have discussed the various cause of slow pace of antileishmanial drug discovery in this review to pay attention of researchers and also take the public and private initiative to make the process fast for new antileishmanial drug development.

Parthenotes are characterized by poor in vitro developmental potential either due to the ploidy status or the absence of paternal factors. In the present study, we demonstrate the beneficial role of sperm-derived factors (SDF) on the in vitro development of mouse parthenotes. Mature (MII) oocytes collected from superovulated Swiss albino mice were activated using strontium chloride (SrCl2) in the presence or absence of various concentrations of SDF in M16 medium. The presence of SDF in activation medium did not have any significant influence on the activation rate. However, a significant increase in the developmental potential of the embryos and increased blastocyst rate (P < 0.01) was observed at 50 µg/ml concentration. Furthermore, the activated oocytes from this group exhibited early cleavage and cortical distribution of cortical granules that was similar to that of normally fertilized zygotes. Culturing 2-cell stage parthenotes in the presence of SDF significantly improved the developmental potential (P < 0.05) indicating that they also play a significant role in embryo development. In conclusion, artificial activation of oocytes with SDF can improve the developmental potential of parthenotes in vitro.

A hydrodynamic model and flow visualization experiments are used to understand the mechanisms through which soluble surfactants can influence the onset of dynamic wetting failure. In the model, a Newtonian liquid displaces air in a rectangular channel in the absence of inertia. A Navier-slip boundary condition and constant contact angle are used to describe the dynamic contact line, and surfactants are allowed to adsorb to the interface and moving channel wall (substrate). The Galerkin finite element method is used to calculate steady states and identify the critical capillary number $Ca^{crit}$ at which wetting failure occurs. It is found that surfactant solubility weakens the influence of Marangoni stresses, which tend to promote the onset of wetting failure. Adsorption of surfactants to the substrate can delay the onset of wetting failure due to the emergence of Marangoni stresses that thicken the air film near the dynamic contact line. The experiments indicate that $Ca^{crit}$ increases with surfactant concentration. For the more viscous solutions used, this behaviour can largely be explained by accounting for changes to the mean surface tension and static contact angle produced by surfactants. For the lowest-viscosity solution used, comparison between the model predictions and experimental observations suggests that other surfactant-induced phenomena such as Marangoni stresses may play a more important role.