Catalytic Mode Research Articles

Challenges and opportunities in microwave-assisted catalytic pyrolysis of biomass: A review

Microwave-assisted catalytic pyrolysis (MACP) is one of the emerging technologies for efficiently converting the solid biomass residues to valuable products, including liquid bio-oil and solid biochar. However, due to the poor dielectric properties, low thermal-conductivity, and complex compositions of biomass feedstock, two major technical challenges of biomass MACP technologies are how to heat biomass efficiently by microwave, and how to tune the pyrolysis process to improve the quality of products by catalysis. In the literature, direct, indirect as well as hybrid (localized and segregated) heating modes have been explored to improve the heating performance of microwave reactors, and in-situ, ex-situ and hybrid (dual, layered and series) catalyst configurations have been applied using different microwave absorbents and catalysts. In this review, those heating and catalysis strategies are systematically and critically reviewed (data from about 80 lab-scale studies and 1 pilot-scale unit) to reveal their differences in terms of heating efficiency and product qualities. For some biomass feedstock with high dielectric properties or under high electromagnetic field, direct heating without the use of microwave absorbent could be used. Indirect heating, on the other hand, can be used for all feedstock in which heat is transferred to the biomass via conduction/convection from high temperature surfaces heated by microwave. Hybrid heating with the use of microwave absorbents can greatly increase the local heating rate, promote the pyrolysis reaction rate and tune the distribution of pyrolytic products. In-situ catalysis shows the capability to tune the quantity and quality of both bio-oil and biochar by promoting direct interaction of catalyst and biomass via the pyrolysis vapour, while ex-situ catalysis exhibits a better potential to adjust the bio-oil yield and selectivity of desired compounds in bio-oil, and extends the catalyst life by avoiding the direct contact between biochar and catalyst. Hybrid catalytic mode combines in-situ and ex-situ catalysis in a more complex setup, but shows a great potential to regulate the yield, composition and properties of multiple products. Techno-economic-environmental assessments were also reported on the benefits of MACP processes with different heating and catalytic strategies, mostly based on the lab and limited pilot scale performance data. Future research and development should be focused on the evaluation of different absorbent-catalyst integration, heating-catalysis synergistic effect, optimization of products yields and properties, and how to scale up the MACP reactor technologies toward commercialization with continuous biomass feeding.

Elucidating the Mechanism of Excited-State Bond Homolysis in Nickel-Bipyridine Photoredox Catalysts.

Ni 2,2'-bipyridine (bpy) complexes are commonly employed photoredox catalysts of bond-forming reactions in organic chemistry. However, the mechanisms by which they operate are still under investigation. One potential mode of catalysis is via entry into Ni(I)/Ni(III) cycles, which can be made possible by light-induced, excited-state Ni(II)-C bond homolysis. Here, we report experimental and computational analyses of a library of Ni(II)-bpy aryl halide complexes, Ni(Rbpy)(R'Ph)Cl (R = MeO, t-Bu, H, MeOOC; R' = CH3, H, OMe, F, CF3), to illuminate the mechanism of excited-state bond homolysis. At given excitation wavelengths, photochemical homolysis rate constants span 2 orders of magnitude across these structures and correlate linearly with Hammett parameters of both bpy and aryl ligands, reflecting structural control over key metal-to-ligand charge-transfer (MLCT) and ligand-to-metal charge-transfer (LMCT) excited-state potential energy surfaces (PESs). Temperature- and wavelength-dependent investigations reveal moderate excited-state barriers (ΔH‡ ∼ 4 kcal mol-1) and a minimum energy excitation threshold (∼55 kcal mol-1, 525 nm), respectively. Correlations to electronic structure calculations further support a mechanism in which repulsive triplet excited-state PESs featuring a critical aryl-to-Ni LMCT lead to bond rupture. Structural control over excited-state PESs provides a rational approach to utilize photonic energy and leverage excited-state bond homolysis processes in synthetic chemistry.

δ-MnO2 decorated layered double oxides in-situ grown on nickel foam towards electrothermal catalysis of n-heptane

Energy-saving and efficient monolithic catalysts are hotspots of catalytic purification of industrial gaseous pollutants. Here, we have developed an electrothermal catalytic mode, in which the ignition temperature required for the reaction is provided by Joule heat generated when the current flows through the catalyst. In this paper, Mn/NiAl/NF, Mn/NiFe/NF and Mn/NF metal-based monolithic catalysts were prepared using nickel foam (NF) as the carrier for thermal and electrothermal catalysis of n-heptane. The results indicated that Mn-based monolithic catalysts exhibit high activity in thermal and electrothermal catalysis. Mn/NiFe/NF achieve conversion of n-heptane more than 99% in electrothermal catalysis under a direct-current (DC) power of 6 W, and energy-saving is 54% compared with thermal catalysis. In addition, the results indicated that the introduction of NiAl (or NiFe) greatly enhanced the catalytic activity of Mn/NF, which attributed to the higher specific surface area, Mn3+/Mn4+, Ni3+/Ni2+, adsorbed oxygen species (Oads)/lattice oxygen species (Olatt), redox performance of the catalyst. Electrothermal catalytic activity was significantly higher than thermal catalytic activity before complete conversion, which may be related to electronic effects. Besides, Mn/NiFe/NF has good cyclic and long-term stability in electrothermal catalysis. This paper provided a theoretical basis for applying electrothermal catalysis in the field of VOCs elimination.

Catalytic semi-continuous operation modes for hydrogen generation from carbon derivatives of ammonia boranes

In the present study, the semi-continuous regime is evaluated for generating hydrogen (H2) from carbon derivatives of ammonia borane (AB) via hydrolysis in presence of cobalt-doped activated carbon catalyst (Co-AC). Methylamine borane (MeAB) and ethane 1,2 diamine borane (EDAB) is used as an H2 storage medium. At first, catalytic activity tests are performed between 20 °C and 80 °C. 0.2 M MeAB, EDAB, and also AB are hydrolyzed with - Co-AC catalyst, and the results are compared in two temperature regions. EDAB shows the lowest hydrogen generation rate at 64.38 mLH2/min.gCo-AC of all carbon derivatives of AB due to its higher thermal stability. The power-law model is used to describe the kinetic rate and activation energy (Ea) for all the reactants in the catalytic hydrolysis reaction and the reaction kinetics studied in two temperature regions as the low-temperature region (20–50 °C) and the high-temperature region (60–80 °C). The zero-order kinetic model describes each temperature region for each reactant. The Ea values of AB, MeAB, and EDAB are calculated as in the range of 48–65 kJ mol-1 for the low-temperature region and in the range of 33–51 kJ mol-1 for the high temperature region. The semi-continuous regimes were performed at 60 °C with the same amount of AB, MeAB, EDAB, and Co-AC catalyst used for catalytic activity tests. The hydrogen generation rates for the semi-continuous regime are calculated to be 2.46 L/h, 0.86 L/h, and 0.17 L/h for AB, MeAB, and EDAB, respectively. The used catalysts and the exhaust solutions are also characterized. After the semicontinuous regime, the characterization results show that Co-AC is stable and Co species does not leach into the exhaust solution. Also, boron is accumulated on the catalyst observed due to by-product formation during the hydrolyses.

1,2‐Boryl Migration Enables Efficient Access to Versatile Functionalized Boronates

AbstractOrganoboronates are synthetically useful and highly valuable building blocks in synthetic and medicinal chemistry. Two‐electron reactions allow for the rapid construction of organoboronates via nucleophilic 1,2‐boron shift of boron ate complexes or MIDA‐mediated 1,2‐boryl migration. Radical approaches through 1,2‐boron shift of neutral boronic esters or boron ate complexes have been demonstrated to be feasible, providing complementary methods to access these privileged scaffolds. In this Review, recent achievements are highlighted and future opportunities are discussed, with an emphasis on different operative modes of catalysis and reaction pathways.

Understanding the catalysis by bis-selenonium cations as bidentate chalcogen bond donors

The mode of activation and catalysis of bidentate bis-selenonium cations have been computationally explored in detail by means of Density Functional Theory calculations. To this end, the parent Diels–Alder cycloaddition reaction between cyclohexadiene and methyl vinyl ketone is compared to the analogous reaction mediated by selenonium cations. It is found that, although the catalyst induces a significant stabilization of the LUMO of the dienophile, the observed acceleration of the process is not due to an enhancement of the orbital interactions between the reactants but to a remarkable reduction of both the steric (Pauli) repulsion between them and the destabilizing strain energy. Issues such as the origin of the endo:exo selectivity of the transformation and the influence of the nature of the tether connecting both selenium centers on the activity of the catalysts are also analyzed in detail.

Synthesis of CaO from waste shells for microwave-assisted catalytic pyrolysis of waste cooking oil to produce aromatic-rich bio-oil

Energy shortage and environmental pollution have attracted long-term attention. In this study, CaO were prepared from waste eggshell (EGC), preserved egg shell (PEC), clam shell (CLC) and crab shell (CRC), which were then compared with commercial CaO (CMC) to catalyze microwave-assisted pyrolysis of waste cooking oil (WCO) for enrichment of aromatics in bio-oil. The characterization results indicated that EGC and CLC contained 95.54% and 95.61% CaO respectively, which were higher than that of CMC (95.11%), and the pore properties of EGC were the best. In addition, the effects of CaO type and catalytic mode on pyrolysis were studied. In CaO catalytic pyrolysis, CMC and CLC in-situ catalysis produced more aromatics than ex-situ catalysis, and PEC and CRC were more conducive to aromatics formation in ex-situ condition. EGC was conducive to produce benzene, toluene and xylene (BTX) both in in-situ (19.04%) and ex-situ (20.76%) catalytic pyrolysis. In CaO/HZSM-5 catalysis, the optimal dual catalytic mode for generating monocyclic aromatic hydrocarbons (MAHs) was Mode A (CaO separated from HZSM-5 for ex-situ catalysis), and EGC/HZSM-5 performed well in benzene, toluene and xylene (BTX) production.

Highly effective microwave catalytic oxidative dehydrogenation of propane by CO2 over V-La-doped dendritic mesoporous silica-based microwave catalysts

The great potential of the oxidative dehydrogenation of propane by CO2 (CO2-ODHP) reaction in facilitating propylene production from propane and elimination of CO2 has attracted much attention. However, the challenge of the oxidative dehydrogenation of propane by CO2 (CO2-ODHP) reaction is the high thermodynamic stability of CO2, which requires high temperature for activation but the predominance of propane cracking reactions at high temperatures leads to difficulties in maintaining high selectivity for propylene at high conversion rates. Herein, a new and effective method for CO2-ODHP by microwave catalysis has been developed. Meanwhile, a novel vanadium-lanthanum-doped three-dimensional dendritic mesoporous silica nanospheres (V-La-MSNS) based microwave catalyst is synthesized by the in situ growth approach. Importantly, the propane conversion increases from 2% in conventional reaction mode (CRM) to 13% in microwave catalytic reaction mode (MCRM) at 500 °C, with the propylene selectivity still remained at a high level. The catalyst exhibits good stability and reproducibility in microwave catalytic reaction mode. Besides, the doping of La in V-MSNS can dramatically increase the catalytic activity. More importantly, the apparent activation energy of the V-La-MSNS + SiC microwave catalyst drops from 132.7 kJ/mol in the CRM to 71.4 kJ/mol in the MCRM, indicating a significant microwave direct catalytic effect. This work presents a new method for high-efficient catalytic CO2-ODHP reaction under microwave irradiation.

Finding and cleaving a holliday junction in long double-stranded DNA: a complete resolution reaction trajectory by single-molecule tracking

Resolution of four-way Holliday junctions (HJs) is a critical intermediate step of Homologous Recombination. HJs are processed by abundant junction-resolving endonucleases that introduce two hydrolytic cleavages. Although their catalytic activity and interaction mode with HJ-DNA have been characterized in great detail by biochemical and structural studies, it remains unclear how the endonucleases find their substrate located in kilobase pairs of duplex DNA. Here, we studied the interaction of the T7 endonuclease I with a long dsDNA molecule that has a junction located at its center.

Catalytic membrane micro-reactor with nano Cu/ZIF-8 assembly in membrane pores by flowing synthesis combining partial ion-exchange

A catalytic membrane micro-reactor (CMMR) is fabricated, with nano Cu/ZIF-8 particles immobilized in the pores of the microfiltration membrane for flow-through catalysis. Nano ZIF-8 is firstly assembled in polyethersulfone (PES) membrane pores by flowing synthesis and then Cu nanoparticles (NPs) are synthesized in-situ in ZIF-8 by the partial ion-exchange reaction. Cu/ZIF-8 nanoparticles are distributed evenly throughout the whole direction of membrane thickness while Cu NPs are dispersed well in ZIF-8. The 4-nitrophenol (4-NP) reduction is used to test the performance of the CMMR. The 4-NP reduction rate being 99.3% is achieved when the membrane flux is 2293 L m −2 h −1 . The CMMR has good stability for over 210 min and presents a surprisingly high apparent reaction rate constant ( K app , 837.43 min −1 ) at room temperature with the loading of ZIF-8 being 85 mg g −1 (PES) and Cu loading cycle number being 1. Compared with batch catalysis by powder catalysts, the K app is increased by 4 orders of magnitude via flow-through catalysis mode using CMMR. The nanoscale configuration of ZIF-8 and Cu NPs assembled inside pores of the membrane enhances remarkably the catalytic activity owing to the enhanced contact and mass transfer in the confined space of membrane pores. A catalytic membrane micro-reactor (CMMR) with nano Cu/ZIF-8 immobilizing in membrane pores was fabricated by flowing synthesis combining partial ion-exchange. This structure provides excellent activities due to the synergistic effect of membrane pores, ZIF-8, and nano Cu. Cu/ZIF-8 catalytic membrane micro-reactor fabricated by flowing synthesis method Cu/ZIF-8 assembled throughout membrane thickness with high loading and dispersity Synergistic effect between membrane pores, ZIF-8 and nano Cu enhances 4-NP reduction Reduction rate of 4-NP over 99.3% achieved with stability over 210 min Apparent reaction rate constant improved by 4 orders of magnitude via flow-through catalysis

Hybrid cycloolefin ligands for palladium–olefin cooperative catalysis

The engineering of molecular catalysts in homogeneous catalysis enables new catalytic modes, which leads to efficient synthetic transformations. In this regard, the design of ligands for transition metal catalysis has played a major role. In transition metal catalysed reactions, olefins can serve as steering ligands by tuning the electronic and steric nature of the metal centre. Here we report unstrained olefin ligands that bear a P or S coordination site for use in the Pd-catalysed Catellani reaction. This olefin ligand shows a covalent catalytic function and enables an efficient ipso,ortho-difunctionalization of iodoarenes. Mechanistic analysis reveals a reversible covalent bonding between the substrate and the cycloolefin unit of the ligand, which forms key organopalladium intermediates to enable a new reactivity. Our results demonstrate a design concept that employs hybrid cycloolefin ligands as a covalent catalytic module, which opens up possibilities for further cooperative catalysis with other transition metal–olefin hybrids. Taking inspiration from palladium–norbornene cooperative catalysis, Catellani-type reactions are now performed using a hybrid olefin ligand with a P or S coordination site. This olefin ligand enables efficient ipso,ortho-difunctionalization of iodoarenes. Mechanistic studies show the formation of organopalladium intermediates that comprise both the substrate and the hybrid olefin ligand.

New polluting metals. Quantification in herbal medicines by voltammetric and spectroscopic analytical methods

A new application of voltammetric techniques in stripping mode to the quantitative determination of metals belonging to the platinum group (PGM) in herbal medicines, at the ultra-trace level, is reported. Pd (II), Pt (II) and Rh (III) are determined by means of square-wave adsorption voltammetry (SWAdSV); Os (VIII) and Ru (III) are determined through square-wave voltammetry in catalytic mode (SWCV); Ir (III) is determined through the application of square-wave catalytic voltammetry in adsorption mode (SWAdCSV). In all the applied methods, the voltammetric cell has the conventional setting with three-electrodes, which sees the presence of a suspended mercury-drop electrode (HMDE) or a glassy carbon electrode (GCE) as working electrodes for the determination of Ir (III). The auxiliary electrode was a platinum electrode, and an Ag∣AgCl∣KClsatd. electrode was employed as reference electrode.Validation of the analytical procedure here proposed has been achieved using reference standards: NIST-SRM 1570a (Spinach Leaves) and NIST-SRM 1573a (Tomato Leaves), both added with pure metal standards, obtaining satisfying precision values, better than the limits set for the validation of quantitative methods. Following the verification of the validity of the here presented procedure, commercially available herbal medicines, based on Eucalyptus globulus, Harpagophytum procumbens DC and Taraxacun officinale weber, were analyzed. Standard samples were also analyzed by atomic absorption spectroscopy, in order to have a reference technique for validating the entire procedure.

Natural Amino Acid L‐Phenylalanine Coordinated Zirconocene Complex as Bifunctional Catalyst for the Synthesis of 1,5‐Benzothiazepines

AbstractTaken the synthesis of 1,5‐benzothiazepines via the condensation between o‐aminothiophenol with ynones as a paradigm, novel mode of IVB metal based bifunctional catalysis in Lewis acidic‐Brønsted basic (LA‐BB) mode, as well as the effective evidence for how the two catalytic sites interact with substrates has been realized and provided respectively. Specifically, the bifunctional catalyst Cp2Zr[OCOCH(NH2)CH2C6H5]2 was formed through in situ coordination between Cp2ZrCl2 and natural amino acid L‐phenylalanine, which was elucidated by 1H NMR experiment and ESI‐MS analysis. Further control experiment reveals that the excellent catalytic efficiency can attribute to coexistence of Zr (IV) center and Brønsted basic NH2 group contained amino acid ligand. More importantly, with the aid of in situ ESI‐MS, the first catalyst‐substrate adduct for IVB metallocene (IV) catalyst was detected, indicating the Lewis acidic catalytic mode of Zr (IV) center on O atom of ynone. Meanwhile, DFT studies indicated that the true catalytic species presumably be zirconocene (IV) bearing both a bidentate and mono‐dentate carboxylate ligand.

Domino Michael/Michael reaction catalyzed by switchable modularly designed organocatalysts.

The domino Michael/Michael reaction between (E)-7-aryl-7-oxohept-5-enals and trans-cinnamaldehydes was investigated by using modularly designed organocatalysts (MDOs). It was found that both the enamine and iminium catalytic modes of the MDOs are switchable and can be individually switched on and off by using appropriate combinations of the precatalyst modules and the reaction conditions. When both the enamine and iminium catalysis modes of the MDOs are switched on, the desired domino reaction products can be obtained in good yields and stereoselectivities under optimized conditions.

Numerical exploration of the flow regime transition of a novel catalytic cracking reactor and operation mode analysis

The maximizing isoparaffins (MIP) reactor has multiple reaction zones by expanding the diameter of the middle section of the conventional equal-diameter FCC riser to produce high-quality gasoline. This study aimed to probe the flow regime transition and corresponding regulation of such diameter-transformed reactors using multiscale CFD simulations with twelve-lump kinetics. It was found that a choking plateau that appears in a low-velocity, equal-diameter riser was captured at a much higher solid concentration in the new reactor when considering reactions, while the plateau disappears and becomes a slowly ascending slope under cold-model conditions. Using the particle circulating mode instead of the fixed mode gives rise to large fluctuations in solids flow and reaction rate in the first zone, but the formation of fast fluidization in the expanded second zone can help stabilize the flow behaviors and product yield. This finding sheds light on the design and operation of diameter-transformed fluidized beds.

Computational Insights into the Esterification of Palmitic Acid with Methanol in Water.

This work provides quantified explanations for the thermodynamic and kinetic characteristics of esterification in aqueous phase, and how phase transfer catalysts improve water phase esterification of fatty acids in a computational-experimental way. Self-catalyzed reaction mode with or without solvation effects, water participated reaction mode, and catalytic reaction mode (catalyzed by p-dodecyl benzene sulfonic acid, DBSA) are discussed. Our results show that the initial self-catalytic reaction mode undergoes the energy barrier of 100.1 kJ/mol, and rises to 148.9 kJ/mol when water molecule is involved, which hinders the esterification reaction. With the DBSA catalyst, this energy barrier will drop to 97.5 kJ/mol and the water phase esterification is successfully promoted with the yield of 81%. The key kinetic factor of binding energy is discussed as that water molecule has a strong reactant binding competitiveness (with the binding energy of -57.9 kJ/mol, and the value for the non-aqueous phase mode is 3.0 kJ/mol) and DBSA has the binding energy with the value of -45.3 kJ/mol, so it can compete with water to form reactant complexes. This work is a successful practice of a computation-experiment combined scheme, and provides a quantitative basis for the improvement of phase transfer catalysts on water phase esterification reactions. The calculation mode and method of aqueous esterification make it possible to convert bio-based fatty acids into fatty acid esters in fermentation broth.

Microenvironment engineering of supported metal nanoparticles for chemoselective hydrogenation.

Selective hydrogenation with supported metal catalysts widely used in the production of fine chemicals and pharmaceuticals often faces a trade-off between activity and selectivity, mainly due to the inability to adjust one factor of the active sites without affecting other factors. In order to solve this bottleneck problem, the modulation of the microenvironment of active sites has attracted more and more attention, inspired by the collaborative catalytic mode of enzymes. In this perspective, we aim to summarize recent advances in the regulation of the microenvironment surrounding supported metal nanoparticles (NPs) using porous materials enriched with organic functional groups. Insights on how the microenvironment induces the enrichment, oriented adsorption and activation of substrates through non-covalent interaction and thus determines the hydrogenation activity and selectivity will be particularly discussed. Finally, a brief summary will be provided, and challenges together with a perspective in microenvironment engineering will be proposed.

Structural and biochemical studies of an iterative ribosomal peptide macrocyclase.

Microviridins, tricyclic peptide natural products originally isolated from cyanobacteria, function as inhibitors of diverse serine-type proteases. Here we report the structure and biochemical characterization of AMdnB, a unique iterative macrocyclase involved in a microviridin biosynthetic pathway from Anabaena sp. PCC 7120. The ATP-dependent cyclase, along with the homologous AMdnC, introduce up to nine macrocyclizations on three distinct core regions of a precursor peptide, AMdnA. The results presented here provide structural and mechanistic insight into the iterative chemistry of AMdnB. In vitro AMdnB-catalyzed cyclization reactions demonstrate the synthesis of the two predicted tricyclic products from a multi-core precursor peptide substrate, consistent with a distributive mode of catalysis. The X-ray structure of AMdnB shows a structural motif common to ATP-grasp cyclases involved in RiPPs biosynthesis. Additionally, comparison with the noniterative MdnB allows insight into the structural basis for the iterative chemistry. Overall, the presented results provide insight into the general mechanism of iterative enzymes in ribosomally synthesized and post-translationally modified peptide biosynthetic pathways.

Characterization and Modeling of Thermostable GH50 Agarases from Microbulbifer elongatus PORT2

Viewing the considerable potential of marine agar as a source for the sustainable production of energy as well as nature-derived pharmaceutics, this work investigated the catalytic activity of three novel GH50 agarases from the mesophilic marine bacterium Microbulbifer elongatus PORT2 isolated from Indonesian coastal seawaters. The GH50 agarases AgaA50, AgaB50, and AgaC50 were identified through genome analysis; the corresponding genes were cloned and expressed in Escherichia coli BL21 (DE3). All recombinant agarases hydrolyzed β-p-nitrophenyl galactopyranoside, indicating β-glycosidase characteristics. AgaA50 and AgaB50 were able to cleave diverse natural agar species derived from Indonesian agarophytes, indicating a promising tolerance of these enzymes for substrate modifications. All three GH50 agarases degraded agarose, albeit with remarkable diversity in their catalytic activity and mode of action. AgaA50 and AgaC50 exerted exolytic activity releasing differently sized neoagarobioses, while AgaB50 showed additional endolytic activity in dependence on the substrate size. Surprisingly, AgaA50 and AgaB50 revealed considerable thermostability, retaining over 75% activity after 1-h incubation at 50 °C. Considering the thermal properties of agar, this makes these enzymes promising candidates for industrial processing.

Asymmetric synthesis of atropisomers enabled by N-heterocyclic carbene catalysis

The research of atropisomerism in synthetic chemistry has drawn growing attention in recent years, owing to its prevalence and importance to natural products, material science and pharmaceutical chemistry. N-Heterocyclic carbene (NHC)-catalyzed reactions for atropisomer construction has emerged as a burgeoning and promising research topic in recent years. This review mainly summarizes the examples for access to atropisomers catalyzed by NHC catalysis, along with the introduction for NHC precursors and patterns of atropisomers involved. To help understanding the progress of NHC-catalyzed atropisomer construction, this review has been documented according to the following four different strategies: annulation, kinetic resolutions, asymmetric desymmetrizations and central-to-axial chirality conversions. Novel methods for NHC-catalyzed atroposelective synthesis are therefore encouraged, including application of novel NHC intermediates and catalytic modes, in the very near future.