Cyclin Y regulates spatial learning and memory flexibility through distinct control of the actin pathway.

Spatial learning and memory flexibility are known to require long-term potentiation (LTP) and long-term depression (LTD), respectively, on a cellular basis. We previously showed that cyclin Y (CCNY), a synapse-remodeling cyclin, is a novel actin-binding protein and an inhibitory regulator of functional and structural LTP in vitro. In this study, we report that Ccny knockout (KO) mice exhibit enhanced LTP and weak LTD at Schaffer collateral-CA1 synapses in the hippocampus. In accordance with enhanced LTP, Ccny KO mice showed improved spatial learning and memory. However, although previous studies reported that normal LTD is necessary for memory flexibility, Ccny KO mice intriguingly showed improved memory flexibility, suggesting that weak LTD could exert memory flexibility when combined with enhanced LTP. At the molecular level, CCNY modulated spatial learning and memory flexibility by distinctively affecting the cofilin-actin signaling pathway in the hippocampus. Specifically, CCNY inhibited cofilin activation by original learning, but reversed such inhibition by reversal learning. Furthermore, viral-mediated overexpression of a phosphomimetic cofilin-S3E in hippocampal CA1 regions enhanced LTP, weakened LTD, and improved spatial learning and memory flexibility, thus mirroring the phenotype of Ccny KO mice. In contrast, the overexpression of a non-phosphorylatable cofilin-S3A in hippocampal CA1 regions of Ccny KO mice reversed the synaptic plasticity, spatial learning, and memory flexibility phenotypes observed in Ccny KO mice. Altogether, our findings demonstrate that LTP and LTD cooperatively regulate memory flexibility. Moreover, CCNY suppresses LTP while facilitating LTD in the hippocampus and negatively regulates spatial learning and memory flexibility through the control of cofilin-actin signaling, proposing CCNY as a learning regulator modulating both memorizing and forgetting processes.

Shank postsynaptic scaffolding proteins in autism spectrum disorder: Mouse models and their dysfunctions in behaviors, synapses, and molecules.

Postsynaptic scaffolding proteins, which are major components of the postsynaptic density (PSD) at excitatory synapses, include Shank, PSD-95, A-kinase anchoring protein, Homer, and SAP90/PSD-95-associated protein families and play crucial roles in synaptic structure, signaling, and functions. Several genetic studies have indicated that postsynaptic scaffolding proteins contribute to the etiology of various psychiatric disorders, including neurodevelopmental disorders. Indeed, mice with mutations or deletions in specific genes encoding postsynaptic scaffolding proteins display alterations in behavioral phenotypes that are relevant to specific psychiatric disorders. Here, we review recent studies on various mutant mouse models of Shank postsynaptic scaffolding proteins associated with autism spectrum disorder, a major neurodevelopmental disorder, and discuss future directions and therapeutic strategies for the treatment of autism spectrum disorder.

Two-dimensional polyaniline (C3N) from carbonized organic single crystals in solid state.

The formation of 2D polyaniline (PANI) has attracted considerable interest due to its expected electronic and optoelectronic properties. Although PANI was discovered over 150 y ago, obtaining an atomically well-defined 2D PANI framework has been a longstanding challenge. Here, we describe the synthesis of 2D PANI via the direct pyrolysis of hexaaminobenzene trihydrochloride single crystals in solid state. The 2D PANI consists of three phenyl rings sharing six nitrogen atoms, and its structural unit has the empirical formula of C3N. The topological and electronic structures of the 2D PANI were revealed by scanning tunneling microscopy and scanning tunneling spectroscopy combined with a first-principle density functional theory calculation. The electronic properties of pristine 2D PANI films (undoped) showed ambipolar behaviors with a Dirac point of -37 V and an average conductivity of 0.72 S/cm. After doping with hydrochloric acid, the conductivity jumped to 1.41 × 10(3) S/cm, which is the highest value for doped PANI reported to date. Although the structure of 2D PANI is analogous to graphene, it contains uniformly distributed nitrogen atoms for multifunctionality; hence, we anticipate that 2D PANI has strong potential, from wet chemistry to device applications, beyond linear PANI and other 2D materials.

Paramagnetic Carbon Nanosheets with Random Hole Defects and Oxygenated Functional Groups.

Ordered graphitic carbon nanosheets (GCNs) were, for the first time, synthesized by the direct condensation of multifunctional phenylacetyl building blocks (monomers) in the presence of phosphorous pentoxide. The GCNs had highly ordered structures with random hole defects and oxygenated functional groups, showing paramagnetism. The results of combined structural and magnetic analyses indicate that the hole defects and functional groups are associated with the appearance and stabilization of unpaired spins. DFT calculations further suggest that the emergence of stabilized spin moments near the edge groups necessitates the presence of functionalized carbon atoms around the hole defects. That is, both hole defects and oxygenated functional groups are essential ingredients for the generation and stabilization of spins in GCNs.

Defect-Free Encapsulation of Fe0 in 2D Fused Organic Networks as a Durable Oxygen Reduction Electrocatalyst.

Because they provide lower cost but comparable activity to precious platinum (Pt)-based catalysts, nonprecious iron (Fe)-based materials, such as Fe/Fe3C and Fe-N-C, have gained considerable attention as electrocatalysts for the oxygen reduction reaction (ORR). However, their practical application is hindered by their poor stability, which is attributed to the defective protection of extremely unstable Fe nanoparticles. Here, we introduce a synthesis strategy for a stable Fe-based electrocatalyst, which was realized by defect-free encapsulation of Fe nanoparticles using a two-dimensional (2D) phenazine-based fused aromatic porous organic network (Aza-PON). The resulting Fe@Aza-PON catalyst showed electrocatalytic activity (half-wave potential, 0.839 V; Tafel slope, 60 mV decade-1) comparable to commercial Pt on activated carbon (Pt/C, 0.826 V and 90 mV decade-1). More importantly, the Fe@Aza-PON displayed outstanding stability (zero current loss even after 100 000 cycles) and tolerance against contamination (methanol and CO poisoning). In a hybrid Li-air battery test, the Fe@Aza-PON demonstrated performance superior to Pt/C.

A Robust 3D Cage-like Ultramicroporous Network Structure with High Gas-Uptake Capacity.

A three-dimensional (3D) cage-like organic network (3D-CON) structure synthesized by the straightforward condensation of building blocks designed with gas adsorption properties is presented. The 3D-CON can be prepared using an easy but powerful route, which is essential for commercial scale-up. The resulting fused aromatic 3D-CON exhibited a high Brunauer-Emmett-Teller (BET) specific surface area of up to 2247 m2 g-1 . More importantly, the 3D-CON displayed outstanding low pressure hydrogen (H2 , 2.64 wt %, 1.0 bar and 77 K), methane (CH4 , 2.4 wt %, 1.0 bar and 273 K), and carbon dioxide (CO2 , 26.7 wt %, 1.0 bar and 273 K) uptake with a high isosteric heat of adsorption (H2 , 8.10 kJ mol-1 ; CH4 , 18.72 kJ mol-1 ; CO2 , 31.87 kJ mol-1 ). These values are among the best reported for organic networks with high thermal stability (ca. 600 °C).

Direct Synthesis of a Covalent Triazine-Based Framework from Aromatic Amides.

There have been extensive efforts to synthesize crystalline covalent triazine-based frameworks (CTFs) for practical applications and to realize their potential. The phosphorus pentoxide (P2 O5 )-catalyzed direct condensation of aromatic amide instead of aromatic nitrile to form triazine rings. P2 O5 -catalyzed condensation was applied on terephthalamide to construct a covalent triazine-based framework (pCTF-1). This approach yielded highly crystalline pCTF-1 with high specific surface area (2034.1 m2 g-1 ). At low pressure, the pCTF-1 showed high CO2 (21.9 wt % at 273 K) and H2 (1.75 wt % at 77 K) uptake capacities. The direct formation of a triazine-based COF was also confirmed by model reactions, with the P2 O5 -catalyzed condensation reaction of both benzamide and benzonitrile to form 1,3,5-triphenyl-2,4,6-triazine in high yield.

Dual-specificity phosphatase 26 (DUSP26) stimulates Aß42 generation by promoting amyloid precursor protein axonal transport during hypoxia.

Amyloid beta peptide (Aß) is a pathological hallmark of Alzheimer's disease (AD) and is generated through the sequential cleavage of amyloid precursor protein (APP) by ß- and γ-secretases. Hypoxia is a known risk factor for AD and stimulates Aß generation by γ-secretase; however, the underlying mechanisms remain unclear. In this study, we showed that dual-specificity phosphatase 26 (DUSP26) regulates Aß generation through changes in subcellular localization of the γ-secretase complex and its substrate C99 under hypoxic conditions. DUSP26 was identified as a novel γ-secretase regulator from a genome-wide functional screen using a cDNA expression library. The phosphatase activity of DUSP26 was required for the increase in Aß42 generation through γ-secretase, but this regulation did not affect the amount of the γ-secretase complex. Interestingly, DUSP26 induced the accumulation of C99 in the axons by stimulating anterograde transport of C99-positive vesicles. Additionally, DUSP26 induced c-Jun N-terminal kinase (JNK) activation for APP processing and axonal transport of C99. Under hypoxic conditions, DUSP26 expression levels were elevated together with JNK activation, and treatment with JNK inhibitor SP600125, or the DUSP26 inhibitor NSC-87877, reduced hypoxia-induced Aß generation by diminishing vesicle trafficking of C99 to the axons. Finally, we observed enhanced DUSP26 expression and JNK activation in the hippocampus of AD patients. Our results suggest that DUSP26 mediates hypoxia-induced Aß generation through JNK activation, revealing a new regulator of γ-secretase-mediated APP processing under hypoxic conditions. We propose the role of phosphatase dual-specificity phosphatase 26 (DUSP26) in the selective regulation of Aß42 production in neuronal cells under hypoxic stress. Induction of DUSP26 causes JNK-dependent shift in the subcellular localization of γ-secretase and C99 from the cell body to axons for Aß42 generation. These findings provide a new strategy for developing new therapeutic targets to arrest AD progression.

Caspase-cleaved tau exhibits rapid memory impairment associated with tau oligomers in a transgenic mouse model.

In neurodegenerative diseases like AD, tau forms neurofibrillary tangles, composed of tau protein. In the AD brain, activated caspases cleave tau at the 421th Asp, generating a caspase-cleaved form of tau, TauC3. Although TauC3 is known to assemble rapidly into filaments in vitro, a role of TauC3 in vivo remains unclear. Here, we generated a transgenic mouse expressing human TauC3 using a neuron-specific promoter. In this mouse, we found that human TauC3 was expressed in the hippocampus and cortex. Interestingly, TauC3 mice showed drastic learning and spatial memory deficits and reduced synaptic density at a young age (2-3months). Notably, tau oligomers as well as tau aggregates were found in TauC3 mice showing memory deficits. Further, i.p. or i.c.v. injection with methylene blue or Congo red, inhibitors of tau aggregation in vitro, and i.p. injection with rapamycin significantly reduced the amounts of tau oligomers in the hippocampus, rescued spine density, and attenuated memory impairment in TauC3 mice. Together, these results suggest that TauC3 facilitates early memory impairment in transgenic mice accompanied with tau oligomer formation, providing insight into the role of TauC3 in the AD pathogenesis associated with tau oligomers and a useful AD model to test drug candidates.

Unusually Stable Triazine-based Organic Superstructures.

Solid-state reactions have been rapidly gaining popularity in organic chemistry owing to their simplicity, efficiency, and selectivity compared to liquid-phase reactions. Herein, we describe the formation of superstructures through the solid-state reaction of an organic single-crystal. The superstructure of 5,5',5''-(1,3,5-triazine-2,4,6-triyl)triisophthalonitrile (TIPN) can be formed by cyclotrimerization of 1,3,5-tricyanobenzene (TCB) single crystals. The TIPN superstructure was confirmed by single crystal X-ray diffraction and visualized by transmission electron microscopy. The superstructure has hexagonally packed 1-dimensional (1D) channels along the crystal axis. Furthermore, the superstructure arises from interdigitated nitrile interactions in the crystal lattice, and thus has electron-beam tolerance and very high thermal stability.

Low levels of methyl ß-cyclodextrin disrupt GluA1-dependent synaptic potentiation but not synaptic depression.

Methyl-ß-cyclodextrin (MßCD) is a reagent that depletes cholesterol and disrupts lipid rafts, a type of cholesterol-enriched cell membrane microdomain. Lipid rafts are essential for neuronal functions such as synaptic transmission and plasticity, which are sensitive to even low doses of MßCD. However, how MßCD changes synaptic function, such as N-methyl-d-aspartate receptor (NMDA-R) activity, remains unclear. We monitored changes in synaptic transmission and plasticity after disrupting lipid rafts with MßCD. At low concentrations (0.5 mg/mL), MßCD decreased basal synaptic transmission and miniature excitatory post-synaptic current without changing NMDA-R-mediated synaptic transmission and the paired-pulse facilitation ratio. Interestingly, low doses of MßCD failed to deplete cholesterol or affect α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor (AMPA-R) and NMDA-R levels, while clearly reducing GluA1 levels selectively in the synaptosomal fraction. Low doses of MßCD decreased the inhibitory effects of NASPM, an inhibitor for GluA2-lacking AMPA-R. MßCD successfully decreased NMDA-R-mediated long-term potentiation but did not affect the formation of either NMDA-R-mediated or group I metabotropic glutamate receptor-dependent long-term depression. MßCD inhibited de-depression without affecting de-potentiation. These results suggest that MßCD regulates GluA1-dependent synaptic potentiation but not synaptic depression in a cholesterol-independent manner.

OCIAD2 activates γ-secretase to enhance amyloid ß production by interacting with nicastrin.

The gamma (γ)-secretase holoenzyme is composed of four core proteins and cleaves APP to generate amyloid beta (Aß), a key molecule that causes major neurotoxicity during the early stage of Alzheimer's disease (AD). However, despite its important role in Aß production, little is known about the regulation of γ-secretase. OCIAD2, a novel modulator of γ-secretase that stimulates Aß production, and which was isolated from a genome-wide functional screen using cell-based assays and a cDNA library comprising 6,178 genes. Ectopic expression of OCIAD2 enhanced Aß production, while reduction of OCIAD2 expression suppressed it. OCIAD2 expression facilitated the formation of an active γ-secretase complex and enhanced subcellular localization of the enzyme components to lipid rafts. OCIAD2 interacted with nicastrin to stimulate γ-secretase activity. OCIAD2 also increased the interaction of nicastrin with C99 and stimulated APP processing via γ-secretase activation, but did not affect Notch processing. In addition, a cell-permeable Tat-OCIAD2 peptide that interfered with the interaction of OCIAD2 with nicastrin interrupted the γ-secretase-mediated AICD production. Finally, OCIAD2 expression was significantly elevated in the brain of AD patients and PDAPP mice. This study identifies OCIAD2 as a selective activator of γ-secretase to increase Aß generation.

Edge-carboxylated graphene nanosheets via ball milling.

Low-cost, high-yield production of graphene nanosheets (GNs) is essential for practical applications. We have achieved high yield of edge-selectively carboxylated graphite (ECG) by a simple ball milling of pristine graphite in the presence of dry ice. The resultant ECG is highly dispersable in various solvents to self-exfoliate into single- and few-layer (≤ 5 layers) GNs. These stable ECG (or GN) dispersions have been used for solution processing, coupled with thermal decarboxylation, to produce large-area GN films for many potential applications ranging from electronic materials to chemical catalysts. The electrical conductivity of a thermally decarboxylated ECG film was found to be as high as 1214 S/cm, which is superior to its GO counterparts. Ball milling can thus provide simple, but efficient and versatile, and eco-friendly (CO(2)-capturing) approaches to low-cost mass production of high-quality GNs for applications where GOs have been exploited and beyond.

Direct solvothermal synthesis of B/N-doped graphene.

Heteroatom-doping into graphitic networks has been utilized for opening the band gap of graphene. However, boron-doping into the graphitic framework is extremely limited, whereas nitrogen-doping is relatively feasible. Herein, boron/nitrogen co-doped graphene (BCN-graphene) is directly synthesized from the reaction of CCl4 , BBr3 , and N2 in the presence of potassium. The resultant BCN-graphene has boron and nitrogen contents of 2.38 and 2.66 atom %, respectively, and displays good dispersion stability in N-methyl-2-pyrrolidone, allowing for solution casting fabrication of a field-effect transistor. The device displays an on/off ratio of 10.7 with an optical band gap of 3.3 eV. Considering the scalability of the production method and the benefits of solution processability, BCN-graphene has high potential for many practical applications.

Large-scale production of edge-selectively functionalized graphene nanoplatelets via ball milling and their use as metal-free electrocatalysts for oxygen reduction reaction.

Edge-selectively functionalized graphene nanoplatelets (EFGnPs) with different functional groups were efficiently prepared simply by dry ball milling graphite in the presence of hydrogen, carbon dioxide, sulfur trioxide, or carbon dioxide/sulfur trioxide mixture. Upon exposure to air moisture, the resultant hydrogen- (HGnP), carboxylic acid- (CGnP), sulfonic acid- (SGnP), and carboxylic acid/sulfonic acid- (CSGnP) functionalized GnPs readily dispersed into various polar solvents, including neutral water. The resultant EFGnPs were then used as electrocatalysts for oxygen reduction reaction (ORR) in an alkaline electrolyte. It was found that the edge polar nature of the newly prepared EFGnPs without heteroatom doping into their basal plane played an important role in regulating the ORR efficiency with the electrocatalytic activity in the order of SGnP > CSGnP > CGnP > HGnP > pristine graphite. More importantly, the sulfur-containing SGnP and CSGnP were found to have a superior ORR performance to commercially available platinum-based electrocatalyst.

Myristoylation-dependent palmitoylation of cyclin Y modulates long-term potentiation and spatial learning.

Many psychiatric disorders accompany deficits in cognitive functions and synaptic plasticity, and abnormal lipid modifications of neuronal proteins are associated with their pathophysiology. Lipid modifications, including palmitoylation and myristoylation, play crucial roles in the subcellular localization and trafficking of proteins. Cyclin Y (CCNY), enriched in the postsynaptic compartment, acts as an inhibitory modulator of functional and structural long-term potentiation (LTP) in the hippocampal neurons. However, cellular and molecular mechanisms underlying CCNY-mediated inhibitory functions in the synapse remain largely unknown. Here, we report that myristoylation located CCNY to the trans-Golgi network (TGN), and subsequent palmitoylation directed the myristoylated CCNY from the TGN to the synaptic cell surface. This myristoylation-dependent palmitoylation of CCNY was required for the inhibitory role of CCNY in excitatory synaptic transmission, activity-induced dynamics of AMPA receptors and PSD-95, LTP, and spatial learning. Furthermore, spatial learning significantly reduced palmitoyl- and myristoyl-CCNY levels, indicating that spatial learning lowers the synaptic abundance of CCNY. Our findings provide mechanistic insight into how CCNY is clustered adjacent to postsynaptic sites where it could play its inhibitory roles in synaptic plasticity and spatial learning.

Aberrant role of pyruvate kinase M2 in the regulation of gamma-secretase and memory deficits in Alzheimer's disease.

Toxic amyloid beta (Aß) species cause synaptic dysfunction and neurotoxicity in Alzheimer's disease (AD). As of yet, however, there are no reported regulators for gamma-secretase, which links a risky environment to amyloid accumulation in AD. Here, we report that pyruvate kinase M2 (PKM2) is a positive regulator of gamma-secretase under hypoxia. From a genome-wide functional screen, we identify PKM2 as a gamma-secretase activator that is highly expressed in the brains of both patients and murine models with AD. PKM2 regulates Aß production and the amount of active gamma-secretase complex by changing the gene expression of aph-1 homolog. Hypoxia induces PKM2 expression, thereby promoting gamma-secretase activity. Moreover, transgenic expression of PKM2 in 3xTg AD model mice enhances hippocampal production of Aß and exacerbates the impairment of spatial and recognition memory. Taken together, these findings indicate that PKM2 is an important gamma-secretase regulator that promotes Aß production and memory impairment under hypoxia.

SERP1 is an assembly regulator of γ-secretase in metabolic stress conditions.

The enzyme γ-secretase generates ß-amyloid (Aß) peptides by cleaving amyloid protein precursor (APP); the aggregation of these peptides is associated with Alzheimer's disease (AD). Despite the development of various γ-secretase regulators, their clinical use is limited by coincident disruption of other γ-secretase-regulated substrates, such as Notch. Using a genome-wide functional screen of γ-secretase activity in cells and a complementary DNA expression library, we found that SERP1 is a previously unknown γ-secretase activator that stimulates Aß generation in cells experiencing endoplasmic reticulum (ER) stress, such as is seen with diabetes. SERP1 interacted with a subcomplex of γ-secretase (APH1A/NCT) through its carboxyl terminus to enhance the assembly and, consequently, the activity of the γ-secretase holoenzyme complex. In response to ER stress, SERP1 preferentially recruited APP rather than Notch into the γ-secretase complex and enhanced the subcellular localization of the complex into lipid rafts, increasing Aß production. Moreover, SERP1 abundance, γ-secretase assembly, and Aß production were increased both in cells exposed to high amounts of glucose and in diabetic AD model mice. Conversely, Aß production was decreased by knocking down SERP1 in cells or in the hippocampi of mice. Compared to postmortem samples from control individuals, those from patients with AD showed increased SERP1 expression in the hippocampus and parietal lobe. Together, our findings suggest that SERP1 is an APP-biased regulator of γ-secretase function in the context of cell stress, providing a possible molecular explanation for the link between diabetes and sporadic AD.

Effects of CYP2D6 and CYP3A5 genotypes on the plasma concentrations of risperidone and 9-hydroxyrisperidone in Korean schizophrenic patients.

This study was conducted to evaluate the effects of the CYP2D6 and CYP3A5 genotypes on the steady-state plasma levels of risperidone (RIS), 9-hydroxyrisperidone (9-OH-RIS), and the active moiety (RIS plus 9-OH-RIS) in Korean schizophrenic patients. Sixty-four Korean schizophrenic patients were enrolled. CYP2D6 and CYP3A5 genotypes were determined, and the plasma levels of RIS and 9-OH-RIS were measured using high-performance liquid chromatography. The dose-normalized plasma concentrations of RIS, 9-OH-RIS, and the active moiety were compared according to the CYP2D6 and CYP3A5 genotypes. Among the patients, 57 were CYP2D6 extensive metabolizers (EMs; CYP2D6*1/*1, *1/*10, and *10/*10) and 7 were CYP2D6 poor metabolizers (PMs; CYP2D6*1/*5 and *10/*5). For the CYP3A5 genotype, 30 patients were CYP3A5*1 expressors (*1/*1 [n = 1] and *1/*3 [n = 29]) and 34 patients were CYP3A5 nonexpressors (*3/*3). The plasma levels of RIS (2.03 ng/mL per milligram for EMs vs 5.57 ng/mL per milligram for PMs, P < 0.001) and 9-OH-RIS (5.06 ng/mL per milligram for EMs vs 0.22 ng/mL per milligram for PMs, P < 0.001) were significantly different among CYP2D6 genotype groups, but the CYP2D6 EMs (7.09 ng/mL per milligram) and PMs (5.79 ng/mL per milligram) did not show no difference in the levels of the active moiety (P = 0.470). CYP3A5 nonexpressors exhibited higher plasma concentrations of both RIS and 9-OH-RIS than its expressors. In the case of 9-OH-RIS, CYP3A5 nonexpressors exhibited significantly higher concentrations than CYP3A5 expressors (5.42 vs 3.51 ng/mL per milligram, P = 0.022). In addition, concentrations of the active moiety were also significantly different between the CYP3A5 nonexpressors (8.39 ng/mL per milligram) and expressors (5.30 ng/mL per milligram, P = 0.005). In conclusion, both CYP2D6 and CYP3A5 genotypes affected plasma levels of RIS and 9-OH-RIS, whereas the active moiety levels were influenced only by the CYP3A5 genotype but not by the CYP2D6 genotype.

Oxidative Dehydrogenation of Ethylbenzene into Styrene by Fe-Graphitic Catalysts.

Carbon-based catalysts have attracted much attention for the dehydrogenation (DH) of organic molecules, due to their rich active sites, high conversion efficiency, and selectivity. However, because of their poor stability at high operation temperature and relatively high cost, their practical applications have been limited. Here, we report a simple ball-milling-induced mechanochemical reaction which can introduce iron (Fe) and different functional groups (mostly stable aromatic C═O after heat-treatment) along the edges of graphitic nanoplatelets. The resulting Fe-graphitic nanoplatelets (Fe-XGnPs, X = H, C, N, or V) provide active sites for the oxidative dehydrogenation (ODH) of ethylbenzene into styrene. Among them, Fe-NGnPs (X = N) displayed the highest performance for styrene production at low temperature (∼11.13 mmol g-1 h-1, 450 °C) with high selectivity and durability.