Spreading Properties Research Articles

Pressure-driven spreadable deferoxamine-laden hydrogels for vascularized skin flaps.

The development of hydrogels that support vascularization to improve the survival of skin flaps, yet establishing homogeneous angiogenic niches without compromising the ease of use in surgical settings remains a challenge. Here, pressure-driven spreadable hydrogels were developed utilizing beta-sheet rich silk nanofiber materials. These silk nanofiber-based hydrogels exhibited excellent spreading under mild pressure to form a thin coating to cover all the regions of the skin flaps. Deferoxamine (DFO) was loaded onto the silk nanofibers to support vascularization and these DFO-laden hydrogels were implanted under skin flaps in rats to fill the interface between the wound bed and the flap using the applied pressure. The thickness of the spread hydrogels was below 200 μm, minimizing the physical barrier effects from the hydrogels. The distribution of the hydrogels provided homogeneous angiogenic stimulation, accelerating rapid blood vessel network formation and significantly improving the survival of the skin flaps. The hydrogels also modulated the immune reactions, further facilitating the regeneration of the skin flaps. Considering the homogeneous distribution at the wound sites, improved vascularization, reduced barrier effects and low inflammation, these hydrogels appear to be promising candidates for use in tissue repair where a high blood supply is in demand. The pressure-driven spreading properties should simplify the use of the hydrogels in surgical settings to facilitate clinical translation.

Investigations of Surface Properties of SAW Fluxes Using CaO-SiO2-TiO2 & Al2O3-CaO-SiO2 Ternary Phase Systems

In the present paper, investigation on wettability and contact angle measurement of twenty-one SAW fluxes for CaO-SiO2-TiO2 & Al2O3-CaO-SiO2 welding flux system at a temperature of 1300 °C was studied. Wettability observed by measuring the contact angle properties of twenty-one SAW fluxes. The purity of flux constituents determined by the XRF technique. Si-O-Si and Al-O-Al symmetric bond behaviour and various crystalline phases observed using FTIR and XRD techniques. Lower contact angle gives higher wetting and spreading properties. The contact angle increased with the increase of TiO2/SiO2 ratio. For the composition range 1.5 to 2.0, there is a higher value of contact angle observed. A maximum increase of contact angle noticed for the composition range 1.5 to 2.0. There is a constant rise in the amount of contact angle for the composition that varies from 1.0 to 1.2.

Stacked invasion waves in a competition-diffusion model with three species

We investigate the spreading properties of a three-species competition-diffusion system, which is not order-preserving. We apply the Hamilton-Jacobi approach, due to Freidlin, Evans and Souganidis, to establish upper and lower estimates of spreading speed for the slowest species, which turn out to be dependent on the spreading speeds of the two faster species. The estimates we obtained are sharp in some situations. The spreading speed is being characterized as the free boundary point of the viscosity solution for certain variational inequality cast in the space of speeds. To the best of our knowledge, this is the first theoretical result on three-species competition system in unbounded domains.

Spreading properties of a three-component reaction-diffusion model for the population of farmers and hunter-gatherers

In this paper, we investigate the spreading properties of solutions of farmer and hunter-gatherer model which is a three-component reaction-diffusion system. Ecologically, the model describes the geographical spreading of an initially localized population of farmers into a region occupied by hunter-gatherers. This model was proposed by Aoki, Shida and Shigesada in 1996. By numerical simulations and some formal linearization arguments, they concluded that there are four different types of spreading behaviors depending on the parameter values. Despite such intriguing observations, no mathematically rigorous studies have been made to justify their claims. The main difficulty comes from the fact that the comparison principle does not hold for the entire system. In this paper, we give theoretical justification to all of the four types of spreading behaviors observed by Aoki et al. Furthermore, we show that a logarithmic phase drift of the front position occurs as in the scalar KPP equation. We also investigate the case where the motility of the hunter-gatherers is larger than that of the farmers, which is not discussed in the paper of Aoki et al.

Urban sensing as a random search process

We study a new random search process: the taxi drive. The motivation for this process comes from urban sensing in which sensors are mounted on moving vehicles such as taxis, allowing urban environments to be opportunistically monitored. Inspired by the movements of real taxis, the taxi drive is composed of both random and regular parts: passengers are brought to randomly chosen locations via deterministic (i.e. shortest paths) routes. We show through a numerical study that this hybrid motion endows the taxi drive with advantageous spreading properties. In particular, on certain graph topologies it offers reduced cover times compared to random walks and persistent random walks.

Dispersion and entropy-like measures of multidimensional harmonic systems: application to Rydberg states and high-dimensional oscillators

The spreading properties of the stationary states of the quantum multidimensional harmonic oscillator are analytically discussed by means of the main dispersion measures (radial expectation values) and the fundamental entropy-like quantities (Fisher information, Shannon and Renyi entropies, disequilibrium) of its quantum probability distribution together with their associated uncertainty relations. They are explicitly given, at times in a closed compact form, by means of the potential parameters (oscillator strength, dimensionality, D) and the hyperquantum numbers $$(n_r,\mu _1,\mu _2,\ldots ,\mu _{D-1})$$ which characterize the state. Emphasis is placed on the highly excited Rydberg (high radial hyperquantum number $$n_r$$ , fixed D) and the high-dimensional (high D, fixed hyperquantum numbers) states. We have used a methodology where the theoretical determination of the integral functionals of the Laguerre and Gegenbauer polynomials, which describe the spreading quantities, leans heavily on the algebraic properties and asymptotical behavior of some weighted $${\mathfrak {L}}_{q}$$ -norms of these orthogonal functions.

Propagation dynamics for monotone evolution systems without spatial translation invariance

In this paper, under an abstract setting we establish the existence of spatially inhomogeneous steady states and the asymptotic propagation properties for a large class of monotone evolution systems without spatial translation invariance. Then we apply the developed theory to study traveling waves and spatio-temporal propagation patterns for time-delayed nonlocal equations, reaction-diffusion equations in a cylinder, and asymptotically homogeneous KPP-type equations. We also obtain the existence of steady state solutions and asymptotic spreading properties of solutions for a time-delayed reaction-diffusion equation subject to the Dirichlet boundary condition.

Antibacterial activities and cytocompatibility of zinc-contained strontium phosphate coating on titanium

Periprosthetic joint infection (PJI) is one of the most pivotal issues accounting for clinical failure of titanium (Ti)-based implants. Therefore, it is of great significance to develop an antibacterial coating with high biocompatibility on the Ti implant surface. In this article, a novel zinc-doped strontium phosphate coating, denoted as Sr-Zn-PCC, was deposited on Ti substrates by phosphate chemical conversion (PCC) method. The texture characterizations indicated that continuous coatings containing SrHPO4, Sr3(PO4)2 and SrZn2(PO4)2 phases were formed on the Ti surface. It is found that the doping of Zn could tune the surface microstructure, roughness, wettability and corrosion resistance of the coatings. The Sr-Zn-PCC coating showed the same bacterial adhesion property at short time (2 h), but tended to hinder biofilm formation on coatings after incubation for up to 24 h. Up to 80% of Staphylococcus aureus (S. aureus) were killed within 24 h by contact with the Sr-Zn-PCC surface. Moreover, cytocompatibility assay indicated that MC-3T3 cells had good adhesion, spreading properties on the coatings, suggesting that it is a promising alloy with both excellent antibacterial ability and high biocompatibility for the applications on orthopedic implants.

Spreading linear triple systems and expander triple systems

The existence of Steiner triple systems STS(n) of order n containing no nontrivial subsystem is well known for every admissible n. We generalize this result in two ways. First we define the expander property of 3-uniform hypergraphs and show the existence of Steiner triple systems which are almost perfect expanders.Next we define the strong and weak spreading properties of linear hypergraphs, and determine the minimum size of a linear triple system with these properties, up to a small constant factor. This property is strongly connected to the connectivity of the structure and of the so-called influence maximization. We also discuss how the results are related to Erdős’ conjecture on locally sparse STSs, influence maximization, subsquare-free Latin squares and possible applications in finite geometry.

Anisotropic tempered diffusion equations

We introduce a functional framework which is specially suited to formulate several classes of anisotropic evolution equations of tempered diffusion type. Under an amenable set of hypothesis involving a very natural potential function, these models can be shown to belong to the entropy solution framework devised by Andreu et al. (2005), therefore ensuring well-posedness. We connect the properties of this potential with those of the associated cost function, thus providing a link with optimal transport theory and a supply of new examples of relativistic cost functions. Moreover, we characterize the anisotropic spreading properties of these models and we determine the Rankine–Hugoniot conditions that rule the temporal evolution of jump hypersurfaces under the given anisotropic flows.

Facile fabrication of super-hydrophilic porous graphene with ultra-fast spreading feature and capillary effect by direct laser writing

This study demonstrated a facile method to fabricate super-hydrophilic 3D porous graphene with high capillary force and ultra-fast spreading characteristic by direct laser writing on KMnO4-coated polyimide (PI) films. Highly oxidized laser-induced graphene (OLIG) was obtained with dominated sp2 carbon referring from Raman spectroscopy and X-ray diffraction. In addition, abundant oxygen functional groups and a 3D porous scaffold structure with foam-like flakes were produced based on the results of X-ray photoelectron pattern and scanning electron microscopy. OLIG showed ultra-fast spreading properties that water drops can spread completely within dozens of milliseconds. The morphology and chemical composition also render the new material with good capillary effect. The capillary rate-of-rise test with IR camera demonstrated that the wetted height of OLIG strip can reach around 16 mm within 5 min.

Effect of Ca element on oxygen content, wetting and spreading properties of Au–Ga filler metal

To meet the low oxygen content requirement on filler metals used in high reliable vacuum brazing of power device, Ca was doped into the Au–Ga filler metal, and the effects of Ca on the oxygen content, the wetting and spreading properties of the filler metal were investigated. The results reveal that Ca can effectively decrease the oxygen content in the Au-Ga-Ca filler metal, and the wettability and spreadability of the Au-Ga-Ca filler metal on the Cu substrate were significantly improved. With 0.004 wt % of Ca addition, the oxygen content in the filler metal decreased to 0.0032 wt % and the spreading area increased to a peak value of74.6 mm2. Proper amount of Ca addition can also effectively restrain the growth of intermetallic compounds (IMC) layer at the vacuum brazed filler metal/Cu interface and improve the shear strength of the joints. For the Cu/Au-Ga-0.004Ca/Cu joints vacuum brazed at 480 °C and a vacuum degree of 5 × 10−3 mbar, the IMC/filler metal interface is flat and the IMC layer is uniform in thickness, and shear strength of the joint was 48.3 MPa, 49.5% higher than the Cu/Au–Ga/Cu joint. It is demonstrated that the Au-Ga-0.004Ca filler metal has the best combination property, and high ratio of brazed area can be obtained with Au-Ga-0.004Ca filler metal at a proper vacuum degree in brazing of real components.

Spreading and coherence properties of a rectangular multi-Gaussian Schell-model beam propagating in biological tissues

Based on the extended Huygens–Fresnel integral, the cross-spectral density function of a rectangular multi-Gaussian Schell-model (RMGSM) beam propagating in biological tissues has been derived, and the spreading properties and spectral degree of coherence of an RMGSM beam propagating in biological tissues were studied by using the numerical examples. The results show that an RMGSM beam propagating in biological tissues will first evolve into a rectangular flat-topped beam and then evolve into a Gaussian-like beam due to the influences of the turbulence of biological tissues. It is also found that an RMGSM beam with smaller coherence length can maintain the rectangular flat-topped beam spot at the longer propagation distance.

Water wettability dependence on surface structure of a snail shell

There are many reports on the special wettability of hierarchical surface structures in nature. Snail shells with three types of roughness of 10, 100, and 500 µm have a unique wetting behavior. In the present study, we investigate the influence of the surface structure on the water wettability using snail shells with different surface roughness. The wettability of a water droplet on the samples was evaluated. The three types of roughness on the surface structure of snail shell had higher water droplet spreading properties than the two types of roughness 500 µm and, 10 or 100 µm. Surface structures of snail shells with different surface roughness were simulated using epoxy resins to clarify the mechanism for the dynamics wetting behavior. The contact angle with a hydrophobic nature, of the epoxy resin with the three types of roughness decreased with increasing time, indicating a hydrophilic nature. The base diameter of the epoxy resins with the three types of roughness increased with increasing time. This was larger than that for a flat epoxy resin with hydrophilicity. Other epoxy resins with shell texture containing 100 and 500 or 10 and 500 µm roughness showed almost no change in the contact angle and diameter of the droplet base. The three types of roughness on the sample surface contributed to development of the water droplet spreading. The 10 µm roughness of the sample surface influenced the dynamic contact angles.

In Vitro Functional and Structural Characterization of A Synthetic Clinical Pulmonary Surfactant with Enhanced Resistance to Inhibition

CHF5633 is a novel synthetic clinical pulmonary surfactant preparation composed by two phospholipid species, dipalmitoyl phosphatidylcholine (DPPC) and palmitoyloleoyl phosphatidylglycerol (POPG), and synthetic analogues of the hydrophobic surfactant proteins SP-B and SP-C. In this study, the interfacial properties of CHF5633 in the absence and in the presence of inhibitory serum proteins have been assessed in comparison with a native surfactant purified from porcine lungs and with poractant alpha, a widely used clinical surfactant preparation. The study of the spreading properties of CHF5633 in a Wilhelmy balance, its ability to adsorb and accumulate at air-liquid interfaces as revealed by a multiwell fluorescence assay, and its dynamic behavior under breathing-like compression-expansion cycling in a Captive Bubble Surfactometer (CBS), all revealed that CHF5633 exhibits a good behavior to reduce and sustain surface tensions to values below 5 mN/m. CHF5633 shows somehow slower initial interfacial adsorption than native surfactant or poractant alpha, but a better resistance to inhibition by serum proteins than the animal-derived clinical surfactant, comparable to that of the full native surfactant complex. Interfacial CHF5633 films formed in a Langmuir-Blodgett balance coupled with epifluorescence microscopy revealed similar propensity to segregate condensed lipid domains under compression than films made by native porcine surfactant or poractant alpha. This ability of CHF5633 to segregate condensed lipid phases can be related with a marked thermotropic transition from ordered to disordered membrane phases as exhibited by differential scanning calorimetry (DSC) of CHF5633 suspensions, occurring at similar temperatures but with higher associated enthalpy than that shown by poractant alpha. The good interfacial behavior of CHF5633 tested under physiologically meaningful conditions in vitro and its higher resistance to inactivation by serum proteins, together with its standardized and well-defined composition, makes it a particularly useful therapeutic preparation to be applied in situations associated with lung inflammation and edema, alone or in combined strategies to exploit surfactant-facilitated drug delivery.

Formulation, characterization and evaluation of nanoparticles based dry powder insufflation containing terbutaline sulphate and itraconazole for the treatment of asthma

Many factors affect the pulmonary drug delivery and stability of the nanoparticles an acupuncture consisting of bronchial asthma. Present research envisages on the development of dry powder nanoparticles as insufflation a acupuncture consisting of bronchial asthma (allergy due to Aspergillus fumigatus) using physical mixing and spray drying. Different founding are prepared and characterized with suitable excipients like lactose and trehalose. The particle size distribution of nano milled and spray-dried particles of Terbutaline Sulphate and Itraconazole showed unimodal size distribution. The formulations prepared with trehalose as the carrier showed less Dv90, Dv50 and Dv10 values due to the fineness in the particles of trehalose when compared to lactose. The Dv50 and Dv10 values were in the range of mountains of 0.43-0.89 µm and 0.21–0.49 µm for all formulations, which shows the primary particle size in the nanometer scale. Smooth and nearly spherical particles were produced for spray-dried formulations when compared to milled formulations. Zeta potential comes across until be between +17±0.13 to +32±0.12, which explains the particles as moderately stable. MMAD values ranges from 3.19 µm to 4.78 µm for milled nanoparticles and 3.45 µm to 4.21 µm for spray-dried particles. Formulated nanoparticles exhibited good spreading properties, which will allow all the particles to deposition palmy profusion territories consisting of the lung. In-vitro drug release studies explains that spray-dried formulations of Terbutaline sulpahte and Itraconazole using lactose as excipients released the drug upto 98.9% and 99.1% in 180mts.

Spreading properties of a multi-Gaussian Schell-modelvortex beam in slanted atmospheric turbulence

The cross-spectral density function of a multi-Gaussian Schell-model vortex (MGSMV) beam propagating through slanted atmospheric turbulence was derived, and the influences of the MGSMV beam parameter and slanted atmospheric turbulence on the spreading properties of a MGSMV beam are studied. One can find that a MGSMV beam propagating in slanted atmospheric turbulence can evolve into the flat-topped beam, and a MGSMV beam with larger index N and topological charge M propagating in slanted atmospheric turbulence will lose the dark hollow center and evolve into the Gaussian beam more slowly than the MGSMV beam with smaller index N and topological charge M. It is also found that a MGSMV beam propagating in slanted atmospheric turbulence with larger strucutre parameter C will evolve into Gaussian beam faster, but the influences of zenith angle α on the spreading properties of MGSMV beam in the far field can be ignored.

Preparation of Calcipotriol Emulsion Using Bacterial Exopolysaccharides as Emulsifier for Percutaneous Treatment of Psoriasis Vulgaris.

An exopolysaccharides/calcipotriol (EPS/CPT) emulsion was prepared using bacterial EPS as emulsifier, sunflower oil as an oil phase and CPT as the loaded drug, and the effect of this emulsion on psoriasis vulgaris treatment was evaluated. An EPS composed of mannose (70.56%) and glucose (29.44%) was obtained from the marine mangrove bacteria Bacillus amyloliquefaciens ZWJ (Zhu Wenjing) strain. The EPS has significant emulsifying activity at the concentration of 1.5%. The prepared EPS/CPT emulsion has small and stable particle size, with a drug content of 0.00492%, and good spreading properties. The in vitro drug release results revealed that the emulsion showed a certain sustained release effect. In vitro and in vivo animal experiments show that the EPS/CPT emulsion can effectively treat psoriasis vulgaris by increasing the accumulation of CPT in psoriatic skin lesions and reducing the levels of inflammatory cells and inflammatory factors (TNF and IL6). Additionally, it has a certain effect on reducing the side effects associated with CPT. This study lays a foundation for the research of EPS in the topical application of medical materials and treatment of psoriasis.

Microstructure and mechanical properties of cold metal transfer welded galvanized steel/magnesium alloy dissimilar joints

The joining of magnesium alloy to galvanized steel was realized by cold metal transfer method with AZ31 magnesium alloy welding wire. Weld appearance, microstructure and tensile properties of Mg–steel joints under various welding parameters were investigated with different welding heat inputs. The results showed that magnesium alloy-steel brazed joints had good weld appearance. When the welding heat input was 141 J/mm, Zn elements were enriched in the Zn-rich zone (ZRZ), and the interface layer was composed of a large portion of Mg–Zn phases and minor Mg–Al phases. With the increase of welding heat input, Zn elements in the ZRZ gradually decreased, Fe/Al phase appeared in the interface layer, and the strength of welding joint increased. When the welding heat input was 159 J/mm, the tensile strength of welding joint reached the maximum value of 198 MPa. However, when the welding input was increased to 181 J/mm, Zn element in the ZRZ was burnt and volatilized seriously, resulting in poor wetting and spreading properties of liquid phase at the interface zone of the steel.

A Super Anisotropic Wetting Microstructure Based on Combination of Sharp Edge and Sharp Corner

Anisotropic wetting is important in industrial, medical and agricultural applications. In this paper, a novel microstructure performing prominent ultra-anisotropic wetting properties is proposed, with MEMS fabrication process. This microstructure possesses both sharp edge and sharp corner (SESC) in topography. The sharp edge can hinder liquid spreading significantly, whereas the sharp corner enhance spreading. By lithography technology on polymer film, Parylene-C, the microstructure can be tailored into different shapes to achieve various liquid spreading properties, two of which are demonstrated here. 2-D SESC microstructure illustrates ultra-high contact angle difference in parallel and perpendicular directions as high as 93.8°, as well as bidirectional wetting properties. Another microstructure, namely 3-D SESC microstructure, demonstrates specific unidirectional wetting properties. The unique microstructure proposed in this paper provide new ideas for application of controlling liquid spreading on surface. [2019-0077]