Tomography reveals three-dimensional Turing patterns created by the Belousov-Zhabotinsky reaction running in a microemulsion.

Abstract Chemical systems that remain kinetically dormant until activated have numerous applications in materials science. Herein we present a method for the control of gelation exploits an inbuilt switch: increase pH after induction period urease‐catalyzed hydrolysis urea was used to trigger base‐catalyzed Michael addition water‐soluble trithiol polyethylene glycol diacrylate. The time (minutes hours) either preset through initial concentrations or reaction initiated locally by base, thus...

The interaction of H2+ CO2 has been investigated on Rh dispersed MgO, TiO2, SiO2 and Al2O3 supports. adsorption measurements revealed that, with the exception Rh/SiO2, presence H2 greatly enhances uptake by samples at 373 K. I.r. spectroscopic showed that adsorbed CO formate ion are formed in surface CO2. On Rh/SiO2 there was no enhanced adsorption, only identified i.r. spectroscopy. No such phenomenon observed absence Rh, i.e. support alone. spectra differed from during CO; twin band...

The vapor-phase decomposition of formic acid was studied over Au supported on various materials, with the aim producing CO-free H2. With regards to and H2 formation, Au/SiO2 found be most active catalyst. reaction started at 373 K complete 523 K. Depending nature supports, significant differences were experienced in pathways. On deposited SiO2, CeO2, carbon Norit, dehydrogenation predominated, whereas Al2O3, ZSM-5, TiO2-supported Au, dehydration favored. Pure obtained Au/CeO2 below 473 No...

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTInfrared spectroscopic study of the adsorption isocyanic acidF. Solymosi and T. BansagiCite this: J. Phys. Chem. 1979, 83, 4, 552–553Publication Date (Print):February 1, 1979Publication History Published online1 May 2002Published inissue 1 February 1979https://pubs.acs.org/doi/10.1021/j100467a026https://doi.org/10.1021/j100467a026research-articleACS PublicationsRequest reuse permissionsArticle Views252Altmetric-Citations74LEARN ABOUT THESE...

Density fingering of the chlorite–tetrathionate reaction is studied experimentally in a Hele-Shaw cell. It shown that dispersion curve describing linear regime evolution pattern formation strongly affected by orientation Both growth rate and range wave numbers associated with unstable modes decrease on increasing tilt angle from vertical. From curves, dependence most mode determined compared existing theories. The ratio marginal number, separating stable modes, to number maximum indicates...

Abstract Chemical systems that remain kinetically dormant until activated have numerous applications in materials science. Herein we present a method for the control of gelation exploits an inbuilt switch: increase pH after induction period urease‐catalyzed hydrolysis urea was used to trigger base‐catalyzed Michael addition water‐soluble trithiol polyethylene glycol diacrylate. The time (minutes hours) either preset through initial concentrations or reaction initiated locally by base, thus...

A bistable switch from a low pH (unreacted “off”) state to high (reacted “on”) was obtained in enzyme-loaded gel beads response supra-threshold substrate concentrations.

Abstract The reaction and diffusion of small molecules is used to initiate the formation protective polymeric layers, or biofilms, that attach cells surfaces. Here, inspired by biofilm formation, we present a general method for growth hydrogels from urease enzyme-particles combining production ammonia with pH-regulated polymerization in solution. We show through experiments simulations how propagating basic front thiol-acrylate were continuously maintained localized presence urea, resulting...

Macrotubes with nanostructures are formed at rates of cm s−1 when aqueous zinc sulfate is injected into a silicate solution and gas bubble pinned to the reaction zone. Straight, long (>10 cm), hollow structures diameters 500 μm can be grown, which upon heating luminescent, photodegrade rhodamine B (RhB). The presence ZnO on interior surface confirmed by electron X-ray diffraction.

As a result of the bell-shaped pH-rate characteristic enzymatic processes, feedback may arise in enzyme reactions having non-neutral products. This special type product activation has been shown to lead self-sustained pH oscillations an enzyme-loaded membrane. We investigate possibility model urea-urease reaction, prompted by recent experimental discovery this reaction. An open system is considered which acid and urea are transported cell containing enzyme. Using linear stability analysis we...

The flow injection of sodium silicate solution into a large reservoir lighter cupric sulfate creates single, downward growing precipitation tubes. These hollow structures have diameters in the range 0.8−2.4 mm and can grow several centimeters length. Four distinct growth regimes are observed, their stability terms rate concentration is investigated. Three these resemble behavior reported earlier for solution. However "reverse" conditions studied here reveal one distinctly different regime...

Chemical oscillations in the classic Belousov-Zhabotinsky (BZ) system typically have a period of few minutes, which can be increased significantly by changing organic substrate. Here we show that temperature and concentrations, an increase 3-4 orders magnitude frequency BZ obtained. At elevated temperatures, high concentration mixtures, cerium-catalyzed reaction exhibits sinusoidal with frequencies 10 Hz or greater. We report effect on shape experiments under batch conditions four-variable...

Small-molecule amphiphiles such as aspirin have unique properties arising from a combination of an aromatic hydrophobic part and hydrophilic part. We show that crystals are capable generating convective flows at the air-aqueous interface both Marangoni effects (through weak surface activity) capillarity (surface deformations). The flow-driven motion millimeter-sized was found to depend on presence other ions in solution well distance orientation crystals. interactions lead formation groups...

Feedback driven by enzyme catalyzed reactions occurs widely in biology and has been well characterized single celled organisms such as yeast. There are still few examples of robust oscillators vitro that might be used to study nonlinear dynamical behavior. One the simplest is urea–urease reaction displays autocatalysis increase pH accompanying production ammonia. A clock was obtained from low high batch reactor bistability oscillations were reported a continuous flow rector. However, found...

Density fingering of exothermic autocatalytic fronts in vertically oriented porous media and Hele-Shaw cells is studied theoretically for chemical reactions where the solutal thermal contribution to density changes have opposite signs. The competition between these two effects leads plumes ascending fronts. descending behave strikingly differently as they can feature, some values parameters, fingers constant amplitude wavelength. differences up down going are discussed terms dispersion...

We describe a novel nucleation mechanism of scroll rings in three-dimensional reaction-diffusion systems with anomalous dispersion. The vortices form after the collision two spherical wave fronts from third, trailing that only partially annihilates wake its predecessor. Depending on relative positions three relevant sources, one obtains untwisted or twisted rings. formation both vortex structures is demonstrated for modified Belousov-Zhabotinsky reaction.

Scroll rings are three-dimensional spiral waves of excitation that rotate around circular filaments. In a modified Belousov-Zhabotinsky reaction, these filaments expand, buckle, and build up gradients in rotation phase. The instability is caused by negative filament tension (-4.3x10;{-4}cm;{2}s) . Initial deformations strongest the direction normal to filament's osculating plane, their growth rates decrease rapidly with increasing wave number.