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In this work, we propose a new fire shaping approach for manufacturing glass nozzles that heats a rotating vertical capillary at the Top of a Lateral Flame (TLF). We use image analysis to evaluate its performance focusing on the reproducibility in the nozzle size and shape, and on its symmetry. Our results show that this new approach has satisfactory diameter reproducibility, and produces highly axisymmetric nozzles (with very little nozzle neck offset or misalignment). The shape reproducibility is very good for the same heating position, and additionally, it allows to produce nozzles of different shapes by working at different positions. TLF overcomes the problems of the previous fire shaping approaches, which used a vertical flame. In comparison with pulling, which is a well-established method, TLF has a similar diameter reproducibility and produces a superior symmetry. [ABSTRACT FROM AUTHOR]

The breakup of a charged liquid column is studied numerically using Volume-OF-Fluid (VOF) for a range of timescales where electrokinetic phenomena may become significant, i.e when the time to breakup becomes comparable or shorter than the diffusion and the electroosmotic migration times of charged species. Here we propose a conservative method to deal with the diffusion of a tracer in VOF schemes when the diffusion is limited to one of the phases. The method consists in weighing the diffusivity with the value of the volume fraction computed from the analytically reconstructed interface. In this way, the interface is made impermeable to the tracer, which is conservatively kept within one of the phases. The performance of this method is first tested by comparing simple configurations with existing analytical solutions. In the cases when the diffusion, electroosmotic motion and hydrodynamic singularities compete, the results indicate that, after breakup, charges distribute between droplets differently from models assuming homogeneous and constant electrical conductivities (i.e. no electrokinetic effects). However, such departure does not alter the main hydrodynamic balances leading to well-established scaling laws of breakup. [ABSTRACT FROM AUTHOR]

Abstract: In this review, we aim at establishing a relationship between the fundamentals of the microfluidics technologies used in the Pharmacy field, and the achievements accomplished by those technologies. We describe the main methods for manufacturing micrometer drops, bubbles, and capsules, as well as the corresponding underlying physical mechanisms. In this regard, the review is intended to show non-specialist readers the dynamical processes which determine the success of microfluidics techniques. Flow focusing (FF) is a droplet-based method widely used to produce different types of fluid entities on a continuous basis by applying an extensional co-flow. We take this technique as an example to illustrate how microfluidics technologies for drug delivery are progressing from a deep understanding of the physics of fluids involved. Specifically, we describe the limitations of FF, and review novel methods which enhance its stability and robustness. In the last part of this paper, we review some of the accomplishments of microfluidics when it comes to drug manufacturing and delivery. Special attention is paid to the production of the microencapsulated form because this fluidic structure gathers the main functionalities sought for in Pharmacy. We also show how FF has been adapted to satisfy an ample variety of pharmaceutical requirements to date. [Copyright &y& Elsevier]

Abstract: Fluorescently encoded polymeric microparticles are acquiring great importance in the development of simultaneous multianalyte screening assays. We have developed a very versatile and straightforward method for the production of dye-labeled microparticles with a very reproducible size distribution and freely-chosen and discernible fluorescent properties. Our method combines Flow Focusing technology with a solvent evaporation/extraction procedure in a single step, yielding spherical, non-aggregate and non-porous particles. We have designed a multi-coloured bead array which includes the possibility of modifying the surface properties of the microparticles, which offer excellent properties for covalent attachment of biomolecules such as peptides, oligonucleotides, proteins, etc. We also show the potential of the fluorescently labeled microspheres for the detection of biomolecule (peptides and oligonucelotides) interactions using flow cytometry. [Copyright &y& Elsevier]

Ethylene, a biologically active natural compound, inhibited aflatoxin accumulation by Aspergillus parasiticus on a solid growth medium in a dose-dependent manner at concentrations of 0.1 to 150 ppm. The activity of the nor-1 promoter (an early aflatoxin gene) was reduced to nondetectable levels by similar quantities of ethylene, suggesting that the inhibitory effect on toxin synthesis occurred, at least in part, at the level of transcription. The inhibitory effect of ethylene on aflatoxin accumulation was also observed when A. parasiticus was grown on raw peanuts. Under similar growth conditions and doses, ethylene strongly inhibited development of asci and ascospores in Aspergillus nidulans, with no detectable effect on Hülle cell formation, conidiation, or sterigmatocystin accumulation. During early growth, A. parasiticus and A. nidulans produced ethylene with approximately twofold higher quantities measured in continuous light than in the dark. 1-Methylcyclopropene (an inhibitor of ethylene receptors in plants), light, CO2, temperature, and growth medium composition altered the effect of ethylene on A. nidulans and A. parasiticus. These observations are consistent with the existence of an ethylene sensor molecule that mediates the function of an ethylene-responsive signaling pathway(s) in Aspergillus. [ABSTRACT FROM AUTHOR]

Samples of nine different papers in use in the library, including two mould-contaminated papers, were irradiated with 14.4 kGy in a Co-60 facility. Five of the samples were subsequently subjected to an accelerated UV-ageing process. mechanical (tensile energy absorption and stretch) and optical properties were measured on control and irradiated samples, before and after ageing.For most samples, the effect of ageing on mechanical properties turned out to be larger than that of irradiation. Irradiated and control samples were similarly affected by the accelerated ageing. Mould contaminated samples were still in acceptable conditions of use after irradiation. No discoloration effect was observed after irradiation and/or ageing. [Copyright &y& Elsevier]

• Agronomical biofortification increased Selenium (Se) in Iberian pig diets. • These Se-biofortified diets increased the antioxidant capacity of Iberian pork. • These biofortified diets increased Se in meat but not in blood plasma. • Main meat effects persisted for 2 months after biofortified diet withdrawal. • This biofortification was inexpensive, safe and had long-lasting effects. Due to its valuable high intramuscular fat content and lipid composition, Iberian pork is very prone to rancidity. Selenium (Se) supplementation delays meat post-mortem oxidation, but organic Se reaches tissues more efficiently and durably than the inorganic forms, which may even be toxic at high concentrations. Agronomical Se biofortification (incorporating Se to crops) provides organic Se, is not expensive and is effective and safe for producing animal feed and human food. This study aimed to: (1) Determine the effectiveness of Se-biofortification in triticale crops. (2) Evaluate the use of Se-biofortified triticale grain in Iberian pigs during the pre-finishing vs the pre-finishing + finishing periods to determine the permanence of Se and the effects on pork antioxidant capacity. A 4-ha triticale plot was sprayed with sodium selenate (10 g Se/ha) and a similar, control plot was not sprayed. Treated plot grain had greater Se concentration (430 ± 22 µg Se/kg) than that from the control one (<25 µg). Starting at 7 months of age (m), castrated Iberian pigs were fed with standard concentrate, containing 45 % of triticale, which was standard (Control; Ctrl , n = 10), or the Se-biofortified one (Treated groups; Trt), which were fed until they were 12 m (Se-1 ; n = 10) or until slaughter time (60 days later; Se-2 ; n = 10). Blood samples were collected at the end of the finishing period for Se content and metabolic parameters. Pre-slaughter loin and gluteal ultrasonography was performed. Carcass and prime cuts were weighed, and meat samples analyzed for Se content and meat quality (before or after 7-day maturation; d0 or d7 respectively). Meat Se content was greater in Trt vs Ctrl, and greater in Se-2 vs Se-1. Treatment did not affect body weight nor blood Se content, but it increased ultrasonographic subcutaneous fat thickness in Se-1 and triglyceride blood levels in Se-2. Compared with Ctrl, Se-1 and Se-2 had higher pH on d0 and lower L* and b* colors on d7. Cooking losses were lowest for Se-1. Loin TBARS was greatest (more oxidized pork) on d7 in Ctrl. Pork springiness and resilience at 20% compression were greatest for Se-2. These results suggest (for the first time, as far as we know) a great potential for this sustainable strategy to increase meat antioxidant capacity through agronomical Se biofortification for animal feeding and for Iberian pigs in particular, even after a 2-month period of concentrate withdrawal, which is required for montanera -finished (free-ranging, acorn-fed) animals. [ABSTRACT FROM AUTHOR]

• We describe the whipping instability in gaseous flow focusing. • Whipping instability is explained in terms of the global stability analysis. • We analyze the influence of the geometry on the whipping instability. We study both theoretically and experimentally the whipping instability in axisymmetric gaseous flow focusing realized in a converging-diverging nozzle. The lateral oscillation of both the tapering meniscus and emitted jet is explained in terms of the global linear instability of the lateral mode with the azimuthal number m = 1. A comparison with previous experiments shows good agreement. The distance between the feeding capillary and the nozzle neck hardly affects the m = 1 stability limit for the conditions considered in those experiments. We analyze the influence of the nozzle shape on the parameter conditions leading to whipping. As the nozzle convergence rate (the inverse of the length over which the diameter reduction takes place) increases, the flow becomes more stable under m = 1 perturbations. The above results are in marked contrast with those of the axisymmetric mode m = 0. For the axisymmetric mode, the minimum flow rate increases with the nozzle convergence rate, while the capillary-to-neck distance has considerable influence on the jetting-to-dripping transition. We also conduct experiments with different nozzles and capillary-to-neck distances to examine the effect of those factors on the stability of the jetting regime. The experiments allow us to distinguish between absolute whipping, in which both the tapering meniscus and the emitted jet oscillate, and convective whipping, in which the jet oscillates while the meniscus remains practically steady. Absolute whipping is observed for water and 1-cSt silicone oil focused with the nozzle with the smallest convergence rate and capillary-to-neck distance. The increase of the liquid viscosity stabilizes the liquid meniscus, producing the transition from absolute to convective whipping. In the high-viscosity case, the oscillation of the emitted jet far away from the discharge orifice is considerably affected by the shape of the nozzle in front of its neck. In fact, the increase of the convergence rate and capillary-to-neck distance eliminates the convective whipping as well. The reduction of surface tension enhances absolute whipping. We explain the appearance of the two types of whipping in terms of the flow pattern induced by the nozzle shape in front of the neck. [ABSTRACT FROM AUTHOR]

Coaxial electrospray is a well established procedure to generate coaxial micro- and nano-structures (microcapsules and coaxial fibers). In this work we show the capabilities of a high-precision numerical code using dynamic mapping, analytic Jacobian formulation and the Taylor–Melcher leaky dielectric model (LDM) to deal with real coaxial electrospray configurations. Since the number of parameters involved in the problem is large, we focus on an experimentally tested liquid pair configuration where the thickness, relative position, and end sharpness of the coaxial feeding tubes are geometrical parameters of interest. The effects of those parameters and the voltage applied at the tubes on the coaxial liquid menisci, liquid streamlines, size of jet and core, and electric current are discussed. • The influence of the outlet tube geometry on coaxial electrosprays is studied. • Accurate numerical solutions are given using Taylor–Melcher Leaky Dielectric model • Protruding, flush and recessed tube outlet setups, and edge sharpening are explored • Physical details (streamline patterns, menisci geometries, stresses) are provided [ABSTRACT FROM AUTHOR]

Flow focusing is providing new tools in Analytical Chemistry for its unique combination of simplicity, droplet size control just above the micrometer scale, and aerosol beam collimation. However, the most interesting droplet size range lies at the stability limit of the standard flow focusing operating mode. Nevertheless, that stability limit can be forced down to produce jets on the submicrometer scale by underpinning the cone-like meniscus at the tip of a hypodermic needle. Using a nebulizer design based on that concept, we show that the flow focusing steady jetting regime extends down to the limit imposed by the instability of jet itself, even for Reynolds numbers as low as 10 −2 . This stability enhancement leads to droplet sizes well below those previously obtained with flow focusing. In this work, we experimentally determine the influence on the jet's radius of the liquid flow rate and viscosity, as well as the focusing orifice. We analyze the instability mechanisms that impose the minimum values of the issued flow rate and jet's size. Finally, the jet's breakup and the size of the resulting micron-sized droplets are examined from high-speed optical imaging. [ABSTRACT FROM AUTHOR]

The production of viscoelastic capillary jets with gaseous flow focusing is studied experimentally. In this technique, the liquid is injected at a constant flow rate through a feeding capillary located in front of the discharge orifice. A gas stream coflows with the jet across the orifice driven by a constant pressure drop. The gas stream sucks and drags the liquid, reducing the jet’s diameter well below the orifice diameter. Because of the rheological nature of the liquid, this focusing phenomenon differs from the Newtonian one in several regards. For given values of the polymer concentration, the injected flow rate, and the applied pressure drop, there is an interval of the capillary-to-orifice distance for which the jetting regime is reached. Outside that interval, the jet either suffers from the pull-out instability or breaks up before reaching the discharge orifice. Significant free surface oscillations can be observed in most of the jetting realizations. This oscillatory behavior is caused by a transient die swell effect which continuously appears right at the capillary exit. Ejection interrupts because the jet bulges to such an extent that the free surface pinches. Because of the stabilizing effect of the polymeric contribution to the axial stress, micrometer filaments with lengths up to 1 cm and Weber numbers on the order of 10 − 4 can be produced in front of the discharge orifice. The shear viscous stresses exerted on the emitted jet by the gas stream beyond the discharge orifice prevent the macromolecule recoiling. The resulting extensional viscosity inhibits the break-up process, and thus very long jets are produced. [ABSTRACT FROM AUTHOR]

A novel microfluidic technique has been recently proposed to produce quasi-monodisperse collections of microbubbles with a controlled size. In this technique, a gaseous stream is injected through a T-junction into a microchannel transporting a liquid current. The gas adheres to a hydrophobic strip printed on the channel surface. When the gas and liquid flow rates are set appropriately, a gaseous rivulet flows over that strip. The rivulet breaks up downstream due to a capillary pearling instability, which leads to a quasi-monodisperse collection of microbubbles. Motivated by this application, we here analyze the stability of both gas and liquid rivulets coflowing with a current in a quadrangular microfluidic channel. The results essentially differ from those of cylindrical jets because the contact-line-anchorage condition affects fundamentally the rivulet’s instability nature. The temporal stability analysis shows that the rivulet becomes unstable not only for (unperturbed) contact angles larger than 90° (as can be expected) but also for values smaller than that angle. Interestingly enough, the maximum growth factor exhibits a non-monotonic dependence with respect to the Reynolds number (i.e., the viscosities). In fact, there are intervals of that parameter where the fluid system becomes unstable, while all the perturbations are damped outside that interval. The gaseous rivulet does not stabilize as the Reynolds number decreases, which means that it can be unstable even in the Stokes limit and for contact angles less than 90°. In addition, the stability of a flowing liquid rivulet is not determined by its contact angle exclusively (as occurs in the static case), but by the Reynolds number as well. Liquid rivulets with contact angles less than 90° can be unstable for sufficiently high Reynolds numbers. [ABSTRACT FROM AUTHOR]

The validity of the one-dimensional (1D) (slenderness) approximation to describing the cone-jet mode of electrospraying is examined by comparing its results with those obtained from the two-dimensional (2D) leaky-dielectric model. This comparison shows that the 1D approach provides accurate predictions for the relevant quantities if the (dimensionless) electrical conductivity and/or the Ohnesorge number are sufficiently high. By using the procedure proposed in Gañán-Calvo, A.M. (1999b) (The surface charge in electrospraying: Its nature and its universal scaling laws. Journal of Aerosol Science, 30 , 863–872), we show the suitability of the 1D model to precisely “measure” those quantities in an electrospray experiment. Our method combines a super-resolution image processing technique to detect the liquid free surface in the experimental images, and the numerical integration of the 1D model. In this way, the conduction and surface convection contributions to the current intensity, as well as the electric field over the jet’ surface, are determined in an experimental realization. [ABSTRACT FROM AUTHOR]

Abstract: Light is a major environmental stimulus that has a broad effect on organisms, triggering a cellular response that results in an optimal adaptation enhancing fitness and survival. In fungi, light affects growth, and causes diverse morphological changes such as those leading to reproduction. Light can also affect fungal metabolism, including the biosynthesis of natural products. In this study we show that in Aspergillus nidulans the effect of light on the production of the sterigmatocystin (ST) toxin depends on the glucose concentration. In cultures grown with 1% glucose and exposed to light, ST production was lower than when grown in the dark. This lower ST production coincided with an elevated rate of cellular damage with partial loss of nuclear integrity and vacuolated cytoplasm. However, in cultures grown with 2% glucose these effects were reversed and light enhanced ST production. Glucose abundance also affected the light-dependent subcellular localization of the VeA (velvet) protein, a key regulator necessary for normal light-dependent morphogenesis and secondary metabolism in Aspergilli and other fungal genera. The role of other VeA-associated proteins, particularly the blue-light-sensing proteins LreA and LreB (WC-1 and WC-2 orthologs), on conidiation could also be modified by the abundance of glucose. We also show that LreA and LreB, as well as the phytochrome FphA, modulate not only the synthesis of sterigmatocystin, but also the production of the antibiotic penicillin. [Copyright &y& Elsevier]

• We analyze the stability of transonic flow focusing. • We determine the minimum liquid flow rate for steady jetting. • We derive a scaling law for the jet diameter. We study numerically and experimentally the stability of the transonic flow focusing used in serial femtosecond crystallography (SFX) to place complex biochemical species into the beam focus. Both the numerical and experimental results indicate that the minimum flow rate for steady jetting increases slightly with the gas stagnation pressure. There is a remarkable agreement between the stability limit predicted by the global stability analysis and that obtained experimentally. Our simulations show that the steady jetting interruption at the critical flow rate is caused by the growth of a perturbation with a constant phase shift. This result is consistent with the experimental observations, which indicate that both the meniscus tip and the emitted jet collapse almost simultaneously at the stability limit. We derive a scaling law for the jet diameter as a function of the liquid flow rate and gas density/pressure from more than one hundred simulations. The scaling law provides accurate predictions for the jet diameter within the range of values [0.549,10.9] μ m analyzed in this work. [ABSTRACT FROM AUTHOR]

Abstract: In the present work, two methods for the preparation of lidocaine-loaded PLGA microparticles are compared. The differences between the polymeric particles obtained by solvent evaporation (SEVM) or flow focusing (FF) were studied by means of scanning electron microscopy and surface thermodynamics determinations. A detailed investigation of the capabilities of the polymer particles to load this drug is described. The physical state of the drug in the polymeric particles and the existence of interactions between both entities were studied by differential scanning calorimetry. The main factors determining the lidocaine incorporation and the release kinetics were the synthesis procedure followed, the amount of drug dissolved in the organic phase during the synthesis routine, the type of polymer (molecular weight and end chemical groups) and the size and the hydrophobic/hydrophilic properties of the particles. The FF technology allowed higher drug incorporations and slower release kinetics. The release studies showed a biphasic profile probably due to diffusion-cum-degradation mediated processes. [Copyright &y& Elsevier]

We report a method to generate steady coaxial jets of immiscible liquids with diameters in the range of micrometer/nanometer size. This compound jet is generated by the action of electro-hydrodynamic (EHD) forces with a diameter that ranges from tens of nanometers to tens of micrometers. The eventual jet breakup results in an aerosol of monodisperse compound droplets with the outer Liquid surrounding or encapsulating the inner one. Following this approach, we have produced monodisperse capsules with diameters varying between 10 and 0.15 micrometers, depending on the running parameters. [ABSTRACT FROM AUTHOR]