Controlled Growth Kinetics Research Articles

Constructing Long and Stable Ag‐Al2O3 Core–Shell Nanowires for Humidity Sensing and Triboelectric Energy Generation

Silver nanowires (AgNWs) are a promising alternative material to indium tin oxide as flexible transparent electrodes owing to their excellent optoelectrical properties and mechanical performance. However, the main challenge is the poor stability under diverse environments, ranging from high humidity, chemical exposure, and dynamic mechanical deformation. Herein, ultralong AgNWs (≈100 μm) have been synthesized via controlling growth kinetics by a facile acetic acid‐assisted solvothermal method, further decorated with a thin Al2O3 layer by electrodeposition to form a core–shell architecture. The resultant films based on Ag‐Al2O3 core–shell nanowires (NWs) possess a higher conductivity while preserving the optical transparency due to the enhanced NWs contact. More importantly, the constructed films exhibit strong resistance to various conditions, such as exposure to high temperature/humidity and immersion in NaCl, HCl, and Na2S solutions. The laser‐etched interdigital electrodes based on the chemically stable AgNWs are further integrated with graphene oxide layer for humidity sensing and respiration monitoring. Furthermore, the developed NWs with superior mechanical stability are constructed as triboelectric nanogenerators for electricity generation, and reliable output performance has been demonstrated. This work provides a convenient, scalable, and cost‐effective solution that offers great potential for designing robust, transparent electrodes for next‐generation flexible electronics.

In vitro, modulation of the dominant intestinal microbiota in type 2 diabetics by controlling antimicrobial activity with the methanolic extract of Pistacia lentiscus L.

The intestinal microbiota has become known as the ‘second brain’ a complementary organ for most metabolic and defensive reactions. The study aims to investigate the potential of the methanolic extract of Pistacia lentiscus leaves to modulate the dominant flora in type 2 diabetic patients compared to healthy subjects, by controlling growth kinetics. Comparative study between the dominant flora of type two diabitics (DT2) and helthy subjects (HS) stools. Using fully sterilized experimental space and materials, the germs were isolated through an antimicrobial study, and their microbial growth kinetics, were analyzed both with and without phytotherapeutic treatment in vitro. This was carried out as part of a study into the effect of methanolic extract from the leaves of the Pistacia lentiscus L. plant harvested in north-west Algeria. The study found a decrease in the quantity of lactobacilli and streptococci in DT2 and an inverse relationship between enterobacteria and streptococci in all microbiotas. On the molecular side. The methanolic extract of P lentiscus leaves gave a super antimicrobial effect for E coli and Clostridium sp at concentrations below their Minimum Inhibitory Concentration (2 mg mL-1), compared with the other gram positives studied, lactobacillus and Streptococcus (4 mg mL-1). This beneficial action confirms the high antimicrobial effect of the methanolic extract of P lentiscus leaves with lower concentration for the quantitative restauration of intestinal microbiota, the intermediary between insoluno-resistance and metabolism. Pistacia lentiscus has the potential to modulate the dominant flora in type 2 diabetics, through its regulatory antimicrobial power.

Structural and Electrical Studies on ZnS Quantum Dots Using PEG as Capping Agent

AbstractZinc sulfide (ZnS) nanoparticles are produced in this study utilizing a simple wet‐chemical precipitation procedure using polyethylene glycol (PEG) as a capping agent. To analyze the structural, morphological, electrical, and electronic properties of the material, the ZnS nano powder is studied using X‐ray diffraction (XRD), scanning electron microscopy (SEM), FTIR, UV–visible absorption spectroscopy, and impedance spectroscopy techniques. The XRD patterns confirm the formation of the cubic phase in as‐prepared ZnS samples, whereas SEM and AFM images show the formation of prismatic and spherical morphology of nano crystallites, confirming the XRD results. FTIR spectra confirm formation of ZnS stoichiometric compound with a partial shifting of vibration bands in the presence of PEG in precursor solution. Optical band gap spectra show a blue shift of band gap with decrease in particle size. The controlled growth kinetics in the presence of PEG the ZnS synthesized nanoparticles show a better quantum confinement effect and enhancement of electrical conductivity behavior as predicted from impedance measurements. For the temperature range of the current investigation, the temperature dependence of conductivity is found to obey the Davis‐Mott model.

Study of plasmid-based expression level heterogeneity under plasmid-curing like conditions in Cupriavidus necator

Plasmid expression level heterogeneity in Cupriavidus necator was studied in response to stringent culture conditions, supposed to enhance plasmid instability, through plasmid curing strategies. Two plasmid curing strategies were compared based on their efficiency at generating heterogeneity in batch: rifampicin addition and temperature increase. A temperature increase from 30° to 37 °C was the most efficient plasmid curing strategy. To generate a heterogeneous population in terms of plasmid expression levels, successive batches at supra-optimal culture temperature (i.e. 37 °C) were initially conducted. Three distinct fluorescent subpopulations P0 (not fluorescent), P1 (low fluorescence intensity, median = 1 103) and P2 (high fluorescence intensity, median = 6 103) were obtained. From there, the chemostat culture was implemented to study the long-term stress response under well-controlled environment at defined dilution rates. For dilution rates comprised between 0.05 and 0.10 h-1, the subpopulation P2 (62% vs 90%) was favored compared to P1 cells (54% vs 1%), especially when growth rate increased. Our biosensor was efficient at discriminating subpopulation presenting different expression levels under stringent culture conditions. Plus, we showed that controlling growth kinetics had a stabilizing impact on plasmid expression levels, even under heterogeneous expression conditions.

Stable and highly efficient blue-emitting CsPbBr3 perovskite nanomaterials via kinetic-controlled growth

Compared to the classical II-VI quantum dots (QDs), the reaction kinetics of cesium lead halide perovskite nanocrystals (NCs) are not clear yet because of the fast reaction rate. Here, an Ag+-assisted slow-release strategy is proposed to synthesize CsPbBr3 nanomaterials, where the reaction rate is decreased and the reaction time is prolonged to days. It is found that the Ag+ ions can bind with the PbBr2 precursor, which makes the formation of PbBr64- as the rate-limiting step. Shape conversion from dots to nanowires and then to platelets has been observed for the CsPbBr3. Pure blue-emitting nanoplatelets (NPLs) with near unity photoluminescence quantum yield (QY) are acquired. In addition, the blue-emitting CsPbBr3 solution is very stable, which has been stored for over 1.5 years without performance degradation. A liquid light-emitting diode (LED) prototype is further fabricated and exhibits excellent stability towards driving currents.

Modulation of Growth Kinetics of Vacuum-Deposited CsPbBr3 Films for Efficient Light-Emitting Diodes.

Because of its excellent optical properties and good stability, all-inorganic halide perovskite CsPbX3 (X = I, Br, Cl) has been attracting interest for use in light-emitting diodes (LEDs). One challenge is improving the efficacy of the spatial confinement of excitons for higher luminescence efficiency. Here, we present a simple yet very effective strategy to form fine-grain-structured CsPbBr3 polycrystalline films prepared by thermal co-evaporation. The strategy involves controlling growth kinetics by adjusting the deposition rate, which, along with growth temperature, determines the nucleation rate and therefore the eventual grain structure. A correlation between deposition rate and average grain size was noted except for a very large deposition rate when there were large hillocks, which we attributed to the peculiar growth behavior of PbBr2 films. The growth conditions that produced a nanoscale grain structure and textured orientations without large hillocks also resulted in the highest luminescence efficiency as we anticipated. With the optimized CsPbBr3 light emitters, we demonstrate a green-light-emitting (at 524 nm) LED with a maximum current efficiency of 1.07 cd/A and an extremely narrow electroluminescence spectrum of 18 nm, a result that highlights the potential of vacuum-processed CsPbBr3 films for high-efficiency LEDs.

Analysis of Potentiostatic Current Transients for Multiple Nucleation with Diffusion and Kinetic Controlled Growth

The theoretical aspects of the electrocrystallization on an inert electrode under potentiostatic conditions are considered. The common growth theory of a single new-phase nucleus is analyzed. Two theoretical approaches to the mathematical description of 3D multiple nucleation with diffusion or kinetic controlled growth and their basic assumptions are discussed. Significant differences between above mechanisms of phase formation illustrates in detail. The formulas for obtaining the main nucleation and growth parameters in these models are given.

On the theory of 3D multiple nucleation with kinetic controlled growth

The general theory of the potentiostatic current transients for 3D multiple nucleation with kinetic controlled growth has been analyzed. Analytical expressions for the determination of nucleation/growth parameters have been derived. The cases of instantaneous and progressive nucleation have been considered.

Icosahedral Pt-Ni Nanocrystalline Electrocatalyst: Growth Mechanism and Oxygen Reduction Activity.

Engineering the structure of Pt alloy offers an effective way to the design of high performance electrocatalysts. Herein, we synthesize a sandwich-structured, icosahedral Pt2.1 Ni catalyst through a hot injection method. Its growth involves three steps: 1) burst nucleation of Pt atoms to form a Pt-enriched core, 2) heterogeneous nucleation of Ni atoms onto the Pt core to form a Ni-enriched interlayer, and 3) kinetic controlled growth of a Pt-enriched shell. The Pt-enriched core protects the nanostructure from collapse and mitigates the strain change caused by lattice mismatch, and thus enhances the stability of the structure. The Ni-enriched interlayer induces the electronic modification of the outermost Pt shell, and in turn tunes the activity. The Pt-enriched shell provides more active sites through the exposure of (1 1 1) facets and retards the dissolution of Ni atoms. As a result, this sandwich-structure enables impressive electrocatalytic activity (0.91 mA cm-2 and 0.32 AmgPt-1 @ 0.9 V) and duability.

Electrochemical Nucleation and Growth of Cobalt from Methanesulfonic Acid Electrolyte

Electrochemical nucleation and growth of cobalt onto glassy carbon electrode (GCE) from methanesulfonic acid (MSA) electrolyte was investigated, the influence of pH and cobalt concentration on the electrocrystallization mechanism was also examined. Cyclic voltammetry experiments indicate a pH and cobalt concentration dependence of the onset potential and a deposit phase change with decreasing pH was also noted. From analysis of current transients, the diffusion coefficient of cobalt ion was estimated as 1.89 × 10−5 cm2s−1. The electrocrystallization mechanism for 0.6 mol/L Co2+ follows the instantaneous nucleation with kinetic controlled growth and is independent of the bath pH while the mechanism for 0.2 mol/L Co2+ follows the progressive nucleation with diffusion controlled growth at pH = 2.0 and then goes to instantaneous nucleation with kinetic controlled growth at pH = 1.5 and exhibits a process of progressive nucleation with kinetic controlled growth with lower pH of 1.0.

Influence of temperature on the controlled growth kinetics and superstructural phase formation of indium on a reconstructed Si (113) 3 × 2 surface

The kinetics of growth, thermal stability and superstructural phase formation of the indium atom on a reconstructed Si (113) 3 × 2 surface at room temperature (RT), as well as at high substrate temperature (HT), is discussed. It was observed that at a very low flux rate of 0.08 ML min−1, In-adsorption at RT follows the Frank-van der Merwe (FM) growth mode, while for HT (>200 °C), In-islands (the Volmer–Weber-growth mode) were formed. The residual thermal desorption (RTD) analysis revealed the anomalous behaviour of temperature-driven layering to the clustering rearrangement of In atoms on the Si (113) surface for RT- and 200 °C-grown systems. The RTD study also demonstrates the effect of temperature on growth kinetics as well as on the multilayer/monolayer desorption pathway. The calculated bilayer desorption energy was found to be different for RT- (TB, 0.48 eV) and HT- (TB, 1.57 eV) grown In/Si(113) systems, while the monolayer desorption energy (TM, 2.56 eV) was the same in both the cases. Various coverage-dependent superstructural phases, such as Si(113) 3 × 2 + 3 × 1, 3 × 1, 3 × 2 + 1 × 3 and 1 × 1, have been observed during the RT- and HT-growth of In on the Si (113) surface. A complete phase diagram of In/Si(113) is deduced which depicts the evolution of novel phases as a function of substrate temperature and coverage.

Modeling the growth kinetics of a multi-component stoichiometric compound

The maximal entropy production principle was applied to model the growth kinetics of a multi-component stoichiometric compound. Compared with the solid-solution phase and the non-stoichiometric compound, the dissipation by the trans-interface diffusion makes the interface slow down by decreasing the effective interface mobility and does not result in solute trapping or disorder trapping. An application to the crystallization of a CuZr stoichiometric compound shows that the transition from the thermodynamic-controlled to the kinetic-controlled growth can be predicted.

Surface-Initiated Activators Generated by Electron Transfer for Atom Transfer Radical Polymerization in Detection of DNA Point Mutation

Amplification-by-Polymerization reportedly offers a sensitive and detector-free approach for DNA detection. However, the requirement for an oxygen-free environment when classic radical polymerization reactions are used in signal amplification significantly limits the mobility of this approach for point-of-need applications. We report here the employment of a purge-free controlled/"living" polymerization reaction, activators generated by electron transfer for atom transfer radical polymerization (AGET ATRP), to achieve signal amplification upon DNA hybridization. Its aptitude in simplifying assay procedure and shortening assay turn-around has been demonstrated in this report, which substantiates the feasibility of using Amplification-by-Polymerization for high throughput or portable screening of genetic mutations. In addition, employment of water-soluble ascorbic acid as the reducing agent has overcome the hurdles encountered by heterogeneous AGET ATRP reactions. Optimization of AGET ATRP in the presence of oligonucleotides has been conducted where tris[(2-pyridyl)methyl]amine (TPMA) was selected as the catalyst ligand for its mild reaction rate. Effective polymer growth has been achieved when the concentration of the Cu(II) catalyst was controlled at 20 mM and ascorbic acid at 18 mM. The propagation and termination reaction constants have been derived, purporting the speculated controlled growth kinetics during polymer grafting. A linear relationship between the grafted polymer film thickness and the amount of captured DNA target sequences has been established, which provides the quantification basis during DNA detection. Detection of DNA sequences with single-point mutations has been successful regardless of the mutation site.

Electrochemical impedance spectroscopy study of the SEI formation on graphite and metal electrodes

The long-term formation kinetics of the solid electrolyte interphase (SEI) was studied on graphite electrodes in 1 M LiClO 4/PC with 5% acrylonitrile (AN) as electrolyte additive by electrochemical impedance spectroscopy at 1.0 and 0.5 V versus Li/Li +, i.e. mainly outside the graphite intercalation region. To support the interpretation of the results, comparative experiments with Ni and Pt electrodes were performed at the same potentials. The resistance of the SEI on graphite and nickel shows similar time dependence. Whereas, R SEI of both electrodes exhibits a linear increase after 5–10 h at 1.0 V, a parabolic behavior could be observed at 0.5 V (and even more expressed for Ni at 0.05 V) typical of diffusion controlled growth kinetics. Temperature dependent measurements yielded activation energies for the ionic conduction of the SEI between 0.61 and 0.66 eV. The results were the same for graphite at 0.5 V and nickel at 1.0, 0.5 and 0.05 V.

High-voltage SPM oxidation of ZrN: materials for multiscale applications

Scanning probe microscope (SPM) oxidation was used to form zirconium oxide features on200 nm thick ZrN films. The features exhibit rapid yet controlled growth kinetics, even incontact mode with 70 V dc applied between the probe tip and substrate. The featuresgrown for times longer than 10 s are higher than 200 nm, and reach more than 1000 nm inheight after 300 s. Long-time oxidation experiments and selective etching of the oxides andnitrides lead us to propose that as the oxidation reaches the silicon substrate, delaminationoccurs with the simultaneous formation of a thin layer of new material at the ZrN/Siinterface. High-voltage oxide growth on ZrN is fast and sustainable, and the robust oxidefeatures are promising candidates for multiscale (nanometre-to-micrometre) applications.

Functional oxide nanobelts: materials, properties and potential applications in nanosystems and biotechnology.

Nanobelt is a quasi-one-dimensional structurally controlled nanomaterial that has well-defined chemical composition, crystallographic structure, and surfaces (e.g., growth direction, top/bottom surface, and side surfaces). This article reviews the nanobelt family of functional oxides, including ZnO, SnO2, In2O3, Ga2O3, CdO, and PbO2 and the relevant hierarchical and complex nanorods and nanowires that have been synthesized by a solid-vapor process. The nanobelts are single crystalline and dislocation free, and their surfaces are atomically flat. The oxides are semiconductors that have been used for fabrication of nanosize functional devices of key importance for nanosystems and biotechnology, such as field-effect transistors, gas sensors, nanoresonators, and nanocantilevers. The structurally controlled ZnO nanobelts that exhibit piezoelectric properties are also reviewed. By controlling growth kinetics, we show the success of growing nanobelt-based novel structures whose surfaces are dominated by the polarized +-(0001) facets. Owing to the positive and negative ionic charges on the zinc- and oxygen-terminated +-(0001) surfaces, respectively, a spontaneous polarization is induced across the nanobelt thickness. As a result, helical nanostructures and nanorings are formed by rolling up single-crystal nanobelts; this phenomenon is a consequence of minimizing the total energy contributed by spontaneous polarization and elasticity. The polar surface-dominated ZnO nanobelts are likely to be an ideal system for understanding piezoelectricity and polarization-induced ferroelectricity at nano-scale and they could have applications as one-dimensional nano-scale sensors, transducers, and resonators.

Gold Dendrite Simulation: Root Cause Determination

While dendritic growth for Ag, Sn, and other metals provides jeopardy for the exterior of packaged integrated circuits, we observed Au dendrites inside ceramic packages. The key factors controlling growth kinetics are a combination of bias and two residual chemicals: one hygroscopic component from the die attach material, and gold plating salts. We found dendritic growth rate to be linear with plating salt concentration during laboratory simulations, but were unable to measure the current density dependence. However, the key factor was the presence or absence of residual nonylphenol, tracked down to an inadequate die attach bake schedule. Laboratory simulations produced the same dendrite morphology as seen for failed units. Furthermore, we found dendritic growth would occur only if all three factors were present-bias, nonylphenol, and the plating salts.

Lysozyme crystal growth kinetics in microgravity.

Mach-Zehnder interferometry is applied to quantitatively characterize growth of lysozyme crystals in microgravity. Experiments were performed by the Free Interface Diffusion technique into APCF FID reactors using large seeds. Tracking of the experiments using interferometry allowed to monitor the onset of supersaturation and the seed growth. A large and stable concentration depletion zone around the growing crystal developed, whose time evolution was analyzed. The interferograms were analyzed taking into account finite thickness of the cell by integrating the concentration over the straight lines through the optical path. It was concluded that there may be a quasi-steady state growth mode at the stage when the spacial concentration distribution did not change but its absolute value over all the cell was slowly diminishing. From this portion of the data, an estimate was made of the dimensionless parameter beta R/D where beta is the face kinetic coefficient, R is the effective crystal size and D is the lysozyme diffusivity in solution, as followed from the steady state model. For the assumed quasi steady state data portion, the parameter varies between 0.7 and 0.9 suggesting mixed diffusion-interface kinetic controlled growth.

Interferometric Study of MgSO4·7H2O Single Crystal Growth Kinetics from Solution

The study of surface reaction controlled growth kinetics of a magnesium sulphate heptahydrate single crystal in [110] direction at T = 15 - 32.5 °C and σ = 0.0002 - 0.135 has been performed with the use of interferometric technique. At lower supersaturations the model of dislocation growth fits the experimental data; at higher supersaturations growth is accelerated due to polynuclear two-dimensional nucleation according to the “Birth + Spread” model.

Electrodeposition of cobalt and zinccobalt alloys from a lewis acidic zinc chloride-1-ethyl-3-methylimidazolium chloride molten salt

The electrodeposition of cobalt and zinccobalt alloys on nickel, tungsten, copper, and glassy carbon electrodes was investigated in 40.0–60.0 mole percent (mol%) zinc chloride-1-ethyl-3-methylimidazolium chloride molten salt containing cobalt(II) at 80°C. At potentials positive of 0.15 V (vs. Zn), cobalt deposition on nickel occurs via three-dimensional instantaneous nucleation with diffusion controlled growth of the nuclei. At potentials between 0.1 and 0.0 V, underpotential deposition of zinc on cobalt occurs. At potentials more negative than −0.1 V, bulk zinc deposition takes place via three-dimensional instantaneous nucleation with mixed diffusion and kinetic controlled growth. The zinc content of the ZnCo alloys was found to vary nonlinearly with the deposition potential. X-ray diffraction measurements indicate that the ZnCo deposits with a low zinc content may be amorphous and the crystalline nature of the ZnCo electrodeposits increases as the zinc content of the deposits increases. Addition of propylene carbonate co-solvent to the melt solution decreases the melting temperature of the solution and enables the electrodeposition to be performed at 40°C.