Uniform Shell Thickness Research Articles

Controlling TiO2 photocatalytic behaviour via perhydropolysilazane-derived SiO2 ultrathin shell.

This study addresses the inherent photocatalytic activity of pure titanium dioxide (TiO2), which limits its application as an industrial pigment. To mitigate this issue, a core-shell structure was employed, where TiO2 cores were encapsulated within SiO2 shells. Perhydropolysilazane (PHPS) was introduced as a superior SiO2 precursor over tetraethylorthosilicate (TEOS), resulting in thinner and more uniform SiO2 shells. Utilizing TiO2's photocatalytic properties, hydroxyl radicals facilitated the conversion of PHPS into SiO2via native Si-H bonds, eliminating the need for additional reducing agents. The formation of PHPS-derived TiO2@SiO2 core-shell nanoparticles demonstrated inherent self-limiting behaviour, ensuring uniform shell thickness regardless of PHPS concentration, simplifying the process for large-scale industrial applications compared to TEOS, which demands precise parameter control. Photocatalytic evaluations highlighted significant passivation of TiO2 photocatalytic activity by PHPS-derived TiO2@SiO2 core-shell particles and TiO2/SiO2 thin films. Specifically, TiO2@PHPS nanoparticles achieved 89-96% passivation compared to 30% with TiO2@TEOS, while TiO2/PHPS films degraded only 12% of Eosin B versus 80% with TiO2 films. Moreover, both PHPS-derived nanoparticles and films maintained TiO2's inherent high whiteness and high-refractive-index optical properties, underscoring their suitability for applications in white paint production, cosmetics, and high-refractive-index coatings.

Well-defined core/shell pDA@Ni-MOF heterostructures with photostable polydopamine as electron-transfer-template for efficient photoelectrochemical H2 evolution

Here, novel core/shell polydopamine@Ni-MOF (pDA@Ni-MOF) heterogeneous nanostructures are synthesized via a simple one-pot nucleation-growth technique. This rational core/shell design method provide a uniform Ni-MOF shell thickness (shell: ∼ 10 nm) as well as homogeneous wrapping of pDA templates with quite narrow size distributions. The obtained band properties of bare pDA ( E CB = −0.35 eV and E VB = 2.95 eV vs normal hydrogen electrode (NHE)) and bare Ni-MOF ( E CB = −0.49 eV and E VB = 2.85 eV vs NHE) clearly revealed charge separation is occurred on pDA by absorbing light due to π-π∗ transition, and photogenerated electrons on conduction band (CB) of pDA was migrated to CB of Ni-MOF. Specifically, the photoelectrochemical (PEC) water performance of pDA@Ni-MOF photoanodes with highest current density is recorded as 8.61 mA/cm 2 at 0.77 V vs. RHE under visible LED irradiation, which is significantly higher than bare pDA (0.008 V vs. RHE) and bare Ni-MOF (0.011 V vs. RHE) at the same conditions. Note that, the higher photon absorption properties of pDA in core together with high interaction valence bond between two semiconductors could generate electron rich state giving rise to faster electron transfer kinetics as next generation of MOF based hybrid materials with regular morphologies. • One-pot nucleation-growth me-thod is utilized to produce core/shell pDA@Ni-MOF. • Charge separation is done on pDA by absorbing light due to π-π∗ transition. • Photogenerated electrons on pDA is migrated to Ni-MOF. • Highest current density is recorded as 8.61 mA/cm 2 at 0.77 V vs. RHE. • The charge transfer mechanism is verified by XPS.

Effect of boundary condition and variable shell thickness on the vibration behavior of grid-stiffened composite conical shells

In this research, it is aimed to investigate the effect of boundary condition and variable shell thickness on the vibration behavior of grid-stiffened composite conical shells. In order to fabricate the stiffeners and shell for the experimental study, continuous and woven glass fibers have been used during a filament winding process, respectively. Due to the non-uniform distribution of the stiffeners in a stiffened conical shell, the equivalent thickness varies along the longitudinal axis. The stiffener and shell structures have been reduced into an equivalent shell using smeared method. The governing equations have been solved in order to evaluate the natural frequencies of the grid-stiffened conical shell by the use of first-shear deformation theory (FSDT) along with the power series method. In order to validate the analytical solutions, an experimental modal analysis have been carried out on a real grid-stiffened composite conical shell with uniform shell thickness. In addition, the finite element solution has been provided for further validations. Furthermore, the effects of various geometric parameters, variable shell thickness and boundary conditions have been discussed.

Flow Microreactor Synthesis of Zeolitic Imidazolate Framework (ZIF)@ZIF Core-Shell Metal-Organic Framework Particles and Their Adsorption Properties.

Metal-organic frameworks (MOFs) with core-shell structures enable to enhance intrinsic properties of constituent MOFs and impart additional functional activities. Although shell thickness is a key factor for regulating the properties of core-shell MOF particles, controlling it has been challenging. The widely used batch reactor synthesis cannot produce core-shell particles with uniform shell thickness because of poor reactant mixing. A microreactor could ensure excellent mixing, and that would allow to control shell thickness. In this study, we synthesized zeolitic imidazolate framework-8 (ZIF-8)@ZIF-67 and ZIF-67@ZIF-8 core-shell particles using a microreactor and investigated the effects of the mixing performance on the shell thickness of the obtained particles. Our results demonstrated that rapid mixing was critical for the uniformity of the synthesized particles. The concentration of core particles is another key factor that can preferentially induce heterogeneous nucleation on the surface of the core particles without inducing self-nucleation in the bulk solution, particularly when the self-nucleation rate of the shell MOF is high. The N2 adsorption isotherms of the synthesized particles revealed their unique adsorption properties, which were ascribed to the core-shell structures obtained at low shell formation rates. Our simple and versatile synthesis technique not only allowed the preparation of ZIF@ZIF particles with novel functionalities but also can be extended to synthesize core-shell MOF particles with different combinations of core particles and shells.

Ge Nanocages and Nanoparticles via Microwave-Assisted Galvanic Replacement for Energy Storage Applications

We report a systematic study on the synthesis of highly monodisperse hollow germanium (Ge) nanoparticles (NPs) via galvanic replacement reactions between GeI2 and Ag NPs. By fine-tuning the synthetic parameters such as temperature, precursor molar ratio, ligand concentration, and so forth, the morphology and surface structure of the Ge NPs can be precisely controlled. We also report a method to synthesize solid Ge NPs and Ag@Ge core–shell metal–semiconductor NPs with a controllable uniform shell thickness. An inward diffusion mechanism for galvanic replacement is proposed and supported by imaging the different stages of the reaction and analysis of the products. This mechanism allows the reaction to be self-terminated and achieves nanometer-sized accuracy. The galvanic reaction may be applied to other semiconductors and could serve as a powerful alternative to the classical nucleation-growth mechanism and subsequently advance the scale-up and further energy storage applications.

Construction of Carbon Dots Coated Magnetic Hollow Silica Spheres.

Magnetic hollow silica spheres (MHSS) with uniform cavity size and shell thickness were prepared using functionalized SiO₂ spheres as templates, on which the magnetic particles were uniformly deposited on their surface. The obtained MHSS exhibited a super-paramagnetic behavior at room temperature. Due to large hollow cavity space and super-paramagnetic characteristics, the MHSS were coated with carbon dots with assistance of (3-Aminopropyl) trimethoxysilane (APS). Thus, the preparedMHSS were mixed with citric acid and APS, followed by hydrothermal reaction at 180 °C, to generate carbon quantum dots coated MHSS (MHSS@CDs). Scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray powder scattering (XRD), X-ray energy dispersive spectral analysis (EDS), Raman spectra and laser scattering particle analyzer were applied to characterize the MHSS and MHSS@CDs.

Millimeter-sized capsules prepared using liquid marbles: Encapsulation of ingredients with high efficiency and preparation of spherical core-shell capsules with highly uniform shell thickness using centrifugal force

HypothesisIn our previous study, we prepared millimeter-sized spherical hard capsules by solidifying droplets of liquid monomer or polymer solution placed on superamphiphobic surface. Application of liquid marbles in place of the naked droplets for capsule preparation has a great potential to increase encapsulation efficiency of high volatile ingredients. Further, interfacial thermodynamic prediction of internal configuration of capsules from spreading coefficients may be effective to prepare core/shell capsule. ExperimentsDroplets of liquid monomer containing a volatile ingredient were rolled on superamphiphobic powders to prepare liquid marbles and solidified by photopolymerization. For preparation of core/shell capsules, the liquid marbles injected with an immiscible water droplet were also solidified. FindingsA volatile ingredient could be encapsulated with higher efficiency than our previous method. Interfacial thermodynamic prediction of internal configuration of capsules from spreading coefficients indicated successful formation of core/shell capsules. However, photopolymerization of the liquid marbles in a static condition resulted in formation of not only core/shell capsules but also acorn-type capsules. Furthermore, the core/shell capsules were distorted and the shell thickness was not uniform. Rolling of the liquid marbles, which generated centrifugal force inside of the liquid marbles, was effective to prepare spherical capsules with highly uniform shell thickness.

Topology optimization of shell-infill structures using a distance regularized parametric level-set method

This paper presents a novel topology optimization formulation for shell-infill structures based on a distance regularized parametric level-set method (PLSM). In this method, the outer shell and the infill are represented by two distinct level sets of a single-level set function (LSF). In order to obtain a controllable and uniform shell thickness, a distance regularization (DR) term is introduced to formulate a weighted bi-objective function. The DR term is minimized along with the original objective, regularizing the parametric LSF close to a signed distance function. With the signed distance property, the area between the two-level sets can be contoured as the shell with a uniform thickness. Additionally, the presented formulation retains one important merit of the PLSM that new holes are able to nucleate during the optimization process. With respect to the material of the shell, the infill is filled with a weaker and lighter material with tunable parameters. Particularly, the infill can be pre-designed with isotropic microstructures. Three compliance minimization examples are provided to demonstrate the effectiveness of this formulation.

Co-extrusion of zirconia core-shell rods with controlled porosity in the core

A method for manufacturing bi-layered zirconia rods of core-shell geometry with a porous core and a dense shell has been developed. Core-shell rods were successfully prepared by thermoplastic co-extrusion of assembled feed rods composed of core and shell zirconia feedstocks. Rheological analysis and adjustment of the feedstock viscosities enabled co-extrusion of regular core-shell rods of uniform shell thickness. Tapioca starch was used as a pore-forming agent in the core feedstock. Binder removal and high temperature treatment had to be modified in order to safely remove the starch particles. Sintering analysis revealed constrained sintering of porous cores in the core-shell rods due to the rigid dense shell, which resulted in an increased porosity in the core. Defect-free core-shell rods with a core porosity of up to 40% and different thicknesses of the dense shell were prepared.

Microencapsulated phase change material modified by graphene oxide with different degrees of oxidation for solar energy storage

High thermal performance of microencapsulated phase change material (MEPCM) helps to achieve good solar energy storage behavior. Here, n-dodecanol/melamine resin composite microcapsules modified by graphene oxide (GO) with different oxidation degrees were synthesized, which was applied to study how the oxidation degree of GO influenced the thermal properties of MEPCM. The as-prepared microcapsules were all spherical particles with the average latent heat of 170J/g. TEM analysis showed that MEPCMs with or without GO had obvious core-shell structure with uniform shell thickness. When the dosing of GO was about 0.6wt%, the thermal conductivity of MEPCM/GO with the minimum oxidation degree was enhanced by 115%, while MEPCM/GO with maximum oxidation degree was increased by 72% in thermal conductivity, greatly improving the energy storage efficiency. The result suggested the as-prepared microcapsules with large energy storage capacity and high energy storage efficiency could be a potential material used for solar energy storage.

Plume Activity and Tidal Deformation on Enceladus Influenced by Faults and Variable Ice Shell Thickness.

We investigated the effect of variations in ice shell thickness and of the tiger stripe fractures crossing Enceladus' south polar terrain on the moon's tidal deformation by performing finite element calculations in three-dimensional geometry. The combination of thinning in the polar region and the presence of faults has a synergistic effect that leads to an increase of both the displacement and stress in the south polar terrain by an order of magnitude compared to that of the traditional model with a uniform shell thickness and without faults. Assuming a simplified conductive heat transfer and neglecting the heat sources below the ice shell, we computed the global heat budget of the ice shell. For the inelastic properties of the shell described by a Maxwell viscoelastic model, we show that unrealistically low average viscosity of the order of 1013 Pa s is necessary for preserving the volume of the ocean, suggesting the important role of the heat sources in the deep interior. Similarly, low viscosity is required to predict the observed delay of the plume activity, which hints at other delaying mechanisms than just the viscoelasticity of the ice shell. The presence of faults results in large spatial and temporal heterogeneity of geysering activity compared to the traditional models without faults. Our model contributes to understanding the physical mechanisms that control the fault activity, and it provides potentially useful information for future missions that will sample the plume for evidence of life. Key Words: Enceladus—Tidal deformation—Faults—Variable ice shell thickness—Tidal heating—Plume activity and timing. Astrobiology 17, 941–954.

A Simple and “Green” Method for Synthesis of Magnetic Hollow Silica Spheres and Its <sup>99</sup>Tc<sup>m</sup> Labeled Targeting Studies

The magnetic hollow silica spheres (MHSS) with uniform cavity size and shell thickness were prepared by a simple and “green” method using functionalized SiO2 spheres as templates. Magnetic particles (Fe3O4) were deposited on the SiO2 surface by varying the molar ratio of [Fe2+]/[Fe3+] and the molar concentration of iron salts. The obtained magnetic hollow silica spheres exhibited a super-paramagnetic behavior at room temperature. Scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray powder scattering (XRD) were applied to characterize the MHSS. Besides, their unit cell parameters are calculated according to results indexing to XRD, the MHSS sample prepared at 0.10 M iron salts and 2:1 molar ratio of [Fe2+]/[Fe3+] has a largest cell angle (β) of unit cell. Due to large hollow cavity space and super-paramagnetic characteristics, the inner amino-functionalized MHSS could be labeled with radioisotope 99Tcm to study the MHSS’s magnetic targeting distribution in vivo. These results indicate that the MHSS has potential in the magnetic targeted drug delivery system which reduces the damage to normal cells and improves the therapeutic effect of cancer.

A facile one-pot oxidation-assisted dealloying protocol to massively synthesize monolithic core-shell architectured nanoporous copper@cuprous oxide nanonetworks for photodegradation of methyl orange.

In this report, a facile and effective one-pot oxidation-assisted dealloying protocol has been developed to massively synthesize monolithic core-shell architectured nanoporous copper@cuprous oxide nanonetworks (C-S NPC@Cu2O NNs) by chemical dealloying of melt-spun Al 37 at.% Cu alloy in an oxygen-rich alkaline solution at room temperature, which possesses superior photocatalytic activity towards photodegradation of methyl orange (MO). The experimental results show that the as-prepared nanocomposite exhibits an open, bicontinuous interpenetrating ligament-pore structure with length scales of 20 ± 5 nm, in which the ligaments comprising Cu and Cu2O are typical of core-shell architecture with uniform shell thickness of ca. 3.5 nm. The photodegradation experiments of C-S NPC@Cu2O NNs show their superior photocatalytic activities for the MO degradation under visible light irradiation with degradation rate as high as 6.67 mg min−1 gcat−1, which is a diffusion-controlled kinetic process in essence in light of the good linear correlation between photodegradation ratio and square root of irradiation time. The excellent photocatalytic activity can be ascribed to the synergistic effects between unique core-shell architecture and 3D nanoporous network with high specific surface area and fast mass transfer channel, indicating that the C-S NPC@Cu2O NNs will be a promising candidate for photocatalysts of MO degradation.

Study on transport phenomena in the beam blank continuous casting mould coupling copper mould with molten steel

The copper mould and molten steel were modelled simultaneously by a three-dimensional (3D) model, which couples fluid flow, heat transfer and solidification. Thermal boundary conditions (e.g. air gap distribution, slag resistance, contact resistance) along casting direction and circumference direction were discussed and applied. The results of solid shell thickness distribution were compared with reference experimental data and reasonable agreements were found. The calculations indicate that, the shell thickness distribution along circumference in web was affected by the cross-section sizes. The uniform shell thickness distributions at narrow face and R corner were caused by the scouring of fluid flow. The heat transfer fluxes at hot face of mould were various at different locations.

Effect of the tiger stripes on the deformation of Saturn's moon Enceladus

AbstractEnceladus is a small icy moon of Saturn with active jets of water emanating from fractures around the south pole, informally called tiger stripes, which might be connected to a subsurface water ocean. The effect of these features on periodic tidal deformation of the moon has so far been neglected because of the difficulties associated with implementation of faults in continuum mechanics models. Here we estimate the maximum possible impact of the tiger stripes on tidal deformation and heat production within Enceladus's ice shell by representing them as narrow zones with negligible frictional and bulk resistance passing vertically through the whole ice shell. Assuming a uniform ice shell thickness of 25 km, consistent with the recent estimate of libration, we demonstrate that the faults can dramatically change the distribution of stress and strain in Enceladus's south polar region, leading to a significant increase of the heat production in this area.

Synthesis of ZIF‐8 Hollow Spheres via MOF‐to‐MOF Conversion

AbstractWe report herein the synthesis of ZIF‐8 hollow spheres with uniform size and shell thickness from monodisperse MOF‐5 cubes via the MOF‐to‐MOF conversion strategy. The ZIF‐8 hollow spheres were obtained by reacting micron‐sized MOF‐5 cubes in the 2‐methylimidazole solution under the optimized experimental conditions. Their chemical composition, crystallinity, porosity, and thermal stability were well characterized and their formation was investigated by time‐dependent electron microscopy and X‐ray diffraction analysis. The porous nature of MOF‐5 and the stronger coordination interaction between 2‐methylimidazole and Zn ions are believed to be responsible for the formation of the ZIF‐8 hollow spheres.

Enhanced biomedical heat-triggered carriers via nanomagnetism tuning in ferrite-based nanoparticles

Biomedical nanomagnetic carriers are getting a higher impact in therapy and diagnosis schemes while their constraints and prerequisites are more and more successfully confronted. Such particles should possess a well-defined size with minimum agglomeration and they should be synthesized in a facile and reproducible high-yield way together with a controllable response to an applied static or dynamic field tailored for the specific application. Here, we attempt to enhance the heating efficiency in magnetic particle hyperthermia treatment through the proper adjustment of the core–shell morphology in ferrite particles, by controlling exchange and dipolar magnetic interactions at the nanoscale. Thus, core–shell nanoparticles with mutual coupling of magnetically hard (CoFe2O4) and soft (MnFe2O4) components are synthesized with facile synthetic controls resulting in uniform size and shell thickness as evidenced by high resolution transmission electron microscopy imaging, excellent crystallinity and size monodispersity. Such a magnetic coupling enables the fine tuning of magnetic anisotropy and magnetic interactions without sparing the good structural, chemical and colloidal stability. Consequently, the magnetic heating efficiency of CoFe2O4 and MnFe2O4 core–shell nanoparticles is distinctively different from that of their counterparts, even though all these nanocrystals were synthesized under similar conditions. For better understanding of the AC magnetic hyperthermia response and its correlation with magnetic-origin features we study the effect of the volume ratio of magnetic hard and soft phases in the bimagnetic core−shell nanocrystals. Eventually, such particles may be considered as novel heating carriers that under further biomedical functionalization may become adaptable multifunctional heat-triggered nanoplatforms.

Yolk–Shell Structured Mesoporous Nanoparticles with Thioether-Bridged Organosilica Frameworks

Organic functionalization and structural control of mesoporous materials are important for their applications. This study reports here that yolk–shell structured mesoporous nanoparticles with thioether-bridged organosilica frameworks can be successfully prepared by hydrothermal treatment of mesostructured organic–inorganic hybrid nanospheres. The thioether-bridged yolk–shell nanoparticles have ultrahigh condensation degree, i.e., (T3+Q4)/(Qn+Tm) = 94%, large surface area (400 m2 g–1), accessible ordered mesochannels (2.0 nm), large pore volume (0.67 cm3 g–1), and uniform diameter (290–90 nm), core size (180–40 nm), and shell thickness (19–8 nm). Thanks to the abundant thioether groups and the unique structure, the yolk–shell mesoporous nanoparticles can be used as nanoreactors to generate in situ polyhedral gold nanoparticles into their hollow spaces in a hot tetrachloride aurate aqueous solution. The gold loaded yolk–shell nanoparticles show two strong plasmon resonance bands at 577 and 633 nm with excellent photothermal efficiency. This shows a great potential for photothermal treatment. Furthermore, the thioether-bridged yolk–shell mesoporous nanoparticles exhibited excellent capability for convenient covalent connection of near-infrared dyes, which make them promising candidates for applications in cell and tumor imaging.

Atomic Layer Metal Deposition from Ethanol for Catalytic Applications

Core-shell architectures have been proven beneficial in enhancing nanocatalysts’ activity, selectivity and durability while increasing utilization of precious metals such as Pt, an expensive but highly active catalyst for various electrochemical and chemical reactions, for example the hydrogen oxidation reaction (HOR) and the oxygen reduction reaction (ORR) in proton exchange membrane (PEM) fuel cells. In order to fully utilize benefits of this approach, a reliable synthesis method is essential to produce core-shell nanoparticles with uniform shell thickness tunable in 1 – 3 monolayer range. Usually the Pt monolayer shell is formed via electrochemical routes, such as galvanic displacement of an underpotentially deposited Cu layer.[ 1 ]Here we report a surfactant-free, ethanol-based wet chemical approach to coating metal nanoparticles with uniform Pt atomic layers with high reproducibility and scalability. The principles applied in the coating method will be illustrated with two practical examples. The first example is ordered Ru-Pt core-shell nanocatalysts with enhanced carbon monoxide (CO) tolerance and dissolution resistance for the anodic HOR in PEM fuel cells.[ 2 ] While the hydrogen produced via steam reforming followed by water gas shift reaction contains about 1% of CO which can severely deactivate the current fuel-cell catalysts, recent advances have been made in removing CO to ~ 10 ppm via preferential oxidation of CO in hydrogen feeds (PROX)[ 3 ], renewing the interest in developing CO-tolerant catalysts for using inexpensive reformates (hydrogen with CO impurity) as the fuel other than pure hydrogen. The partial alloying between Ru and Pt is avoided, and thus single crystalline particles are formed though Ru and Pt have distinctly different crystal structures, hexagonal close-packed (hcp) for Ru, and face-centered cubic (fcc) for Pt. Ordered lattice structural transition from Ru(hcp) to Pt(fcc)at the core-shell interface is verified by X-ray diffraction (XRD) and scanning transmission electron microscopy (STEM), coupled with density functional theory (DFT) calculations. Furthermore, the Ru-Pt electrocatalysts with optimized structures and improved Pt utilizations exhibit significantly enhanced CO tolerance and excellent dissolution resistance at ultra-low catalyst loadings for the HOR in fuel-cell tests. This new level of atomic control also solves the dilemma in using a dissolution-prone metal (Ru) for alleviating the deactivating effect of CO. The second example is Pt monolayer coated on Pd nanoparticles with high activities and stabilities for the ORR, the cathodic reaction in PEM fuel cells. The uniformity of Pt shells is verified by various characterization techniques, and DFT calculations also show that two-dimensional growth of Pt on Pd is energetically favorable. The as-prepared Pt monolayer electrocatalysts exhibit high electrocatalytic performance toward the ORR. In conclusion, we have demonstrated a surfactant-free and high-yield chemical route for coating of Pt atomic layers on other metal nanoparticles, which ensures high reproducibility and scalability. The strategy illustrated here could be applicable to the fabrication of other bimetallic or multimetallic core-shell nanoparticles for various applications. Acknowledgements This research was performed at Brookhaven National Laboratory (BNL) under contract DE-AC02-98CH10886 with the U.S. Department of Energy (DOE).

Light-treated silica-coated gold nanorods having highly enhanced catalytic performances and reusability

A simple post-treatment method of irradiation with a Xe lamp for 2h has been observed to enhance the catalytic performances of a nanocatalyst on a large scale. The light treatment of mesoporous silica-coated gold nanorods having an average diameter of 17.5nm and a typical aspect ratio of 4 with a uniform shell thickness of 20nm improves the catalytic activity of the nanocatalyst for the reduction of 4-nitrophenol in the presence of NaBH4 extensively without deteriorating the encapsulation effect of mesoporous silica that enhances the stability and reusability of the nanocatalyst by preventing the aggregation and dissolution of gold nanorods. Irradiation increases the catalytic rate constant largely with reducing the activation energy and the induction time of the catalytic reaction substantially; surface atom restructuring induced by photothermal annealing during irradiation has rendered the metallic surface to adsorb reactants easily and to facilitate rapid electron relays from BH4− to 4-nitrophenol, lowering the kinetic barrier of the catalytic reaction considerably.