Improving the hydrothermal stability of Al-rich Cu-SSZ-13 zeolite via Pr-ion modification.

Al-rich (Si/Al = 4-6) Cu-SSZ-13 has been recognized as one of the potential catalysts to replace the commercial Cu-SSZ-13 (Si/Al = 10-12) towards ammonia-assisted selective catalytic reduction (NH3-SCR). However, poor hydrothermal stability is a great obstacle for Al-rich zeolites to meet the catalytic applications containing water vapor. Herein, we demonstrate that the hydrothermal stability of Al-rich Cu-SSZ-13 can be dramatically enhanced via Pr-ion modification. Particularly, after high-temperature hydrothermal aging (HTA), CuPr1.2-SSZ-13-HTA with an optimal Pr content of 1.2 wt% exhibits a T80 (temperature window of NO conversion above 80%) window of 225-550 °C and a T90 window of 250-350 °C. These values are superior to those of Cu-SSZ-13-HTA (225-450 °C for T80 and no T90 window). The results of X-ray diffraction Rietveld refinement, electron paramagnetic resonance (EPR) and spectral characterization reveal that Pr ions mainly located in the eight-membered rings (8MRs) in SSZ-13 zeolite can inhibit the generation of inactive CuOx during hydrothermal aging. This finding is further supported by density functional theory (DFT) calculations, which suggest that the presence of Pr ions restrains the transformation from Cu2+ ions in 6MRs into CuOx, resulting in enhanced hydrothermal stability. It is also noted that an excessive amount of Pr ions in Cu-SSZ-13 would result in the production of CuOx that causes the decline of catalytic performance. The present work provides a promising strategy for creating a hydrothermally stable Cu-SSZ-13 zeolite catalyst by adding secondary metal ions.

Cu-OFF/ERI Zeolite: Intergrowth Structure Synergistically Boosting Selective Catalytic Reduction of NOx with NH3.

Cu-SSZ-13 has been commercialized for selective catalytic reduction with ammonia (NH3-SCR) to remove NOx from diesel exhaust. As its synthesis usually requires toxic and costly organic templates, the discovery of alternative Cu-based zeolite catalysts with organotemplate-free synthesis and comparable or even superior NH3-SCR activity to that of Cu-SSZ-13 is of great academic and industrial significance. Herein, we demonstrated that Cu-T with an intergrowth structure of offretite (OFF) and erionite (ERI) synthesized by an organotemplate-free method showed better catalytic performance than Cu-ERI and Cu-OFF as well as Cu-SSZ-13. Structure characterizations and density functional theory calculations indicated that the intergrowth structure promoted more isolated Cu2+ located at the 6MR of the intergrowth interface, resulting in a better hydrothermal stability of Cu-T than Cu-ERI and Cu-OFF. Strikingly, the low-temperature activity of Cu-T significantly increased after hydrothermal aging, while that of Cu-ERI and Cu-OFF substantially decreased. Based on in situ diffuse reflectance infrared Fourier transform spectra analysis and density functional theory calculations, the reason can be attributed to the fact that NH4NO3 formed on the CuxOy species within ERI polymorph of Cu-T underwent a fast SCR reaction pathway with the assistance of Brønsted acid sites at the intergrowth interfaces under standard SCR reaction conditions. Significantly, Cu-T exhibited a wider temperature window at a catalytic activity of over 90% than Cu-SSZ-13 (175-550 vs 175-500 °C for fresh and 225-500 vs 250-400 °C for hydrothermal treatment). This work provides a new direction for the design of high-performance NH3-SCR catalysts in terms of the interplay of the intergrowth structure of zeolites.

Coaxial 3D Printing of Zeolite-Based Core-Shell Monolithic Cu-SSZ-13@SiO2 Catalysts for Diesel Exhaust Treatment.

Core-shell catalysts with functional shells can increase the activity and stability of the catalysts in selective catalytic reduction of NOx with ammoniax . However, the conventional approaches based on multistep fabrication for core-shell structures encounter persistent restrictions regarding strict synthesis conditions and limited design flexibility. Herein, a facile coaxial 3D printing strategy is for the first time developed to construct zeolite-based core-shell monolithic catalysts with interconnected honeycomb structures, in which the hydrophilic noncompact silica serves as shell and Cu-SSZ-13 zeolite acts as core. Compared to a Cu-SSZ-13 monolith which suffers from the interfacial diffusion, the SiO2 shell layer can increase the accessibility of active sites over Cu-SSZ-13@SiO2 , resulting in a 10-20% higher NO conversion at200-550 °C under 300 000 cm3 g-1 h-1 . Meanwhile, a thicker SiO2 shell enhances the hydrothermal stability of the aged catalyst by inhibiting the dealumination and the formation of CuOx . Other representative monolithic catalysts with different topological zeolites as shell and diverse metal oxides as the core can be also realized by this coaxial 3D printing. This strategy allows multiple porous materials to be directly integrated, which allows for flexible design and fabrication of various core-shell monolithic catalysts with customized functionalities.

Low-silica Cu-CHA Zeolite Enriched with Al Pairs Transcribed from Silicoaluminophosphate Seed: Synthesis and Ammonia Selective Catalytic Reduction Performance.

Cu-exchanged low-silica CHA zeolites (Si/Al≤4) synthesized without organic templates are promising candidate catalysts for ammonia selective catalytic reduction of nitrogen oxides (NH3 -SCR), but their practical application is restricted due to the low hydrothermal stability. Here, inspired by the transcription from duplex DNA to RNA, we synthesized Al pairs enriched low-silica CHA zeolite (CHA-SPAEI, Si/Al=3.7) by using silicoaluminophosphate (SAPO) featured by strict alternation of -Al-O-P(Si)-O-Al-O- tetrahedra as seed. The proportion of Al pairs in CHA-SPAEI is 78 %, which is much higher than that in the conventional low-silica CHA (CHA-LS, 52 %). After hydrothermal ageing at 800 °C for 6 h, Cu-exchanged CHA-SPAEI shows NO conversion above 90 % within 225-500 °C under a gas hourly space velocity of 200,000 h-1 , which is much better than that of Cu-exchanged CHA-LS. The spatial close proximity of Al pairs in CHA-SPAEI is confirmed by the 27 Al double-quantum single-quantum two-dimensional NMR analyses. The strict -P(Si)-O-Al-O-P(Si)-O- sequence in the fragments from the dissolution of SAPO seed promotes the Al pairs with the -Al-O-Si-O-Al-O- sequence via a transcription process. The utilization of aluminophosphate-based zeolites as seeds opens up a new avenue for the regulation of the Al distribution in zeolites.

Steam-assisted crystallization of highly dispersed nanosized hierarchical zeolites from solid raw materials and their catalytic performance in lactide production.

A solvent-free route based on solid raw materials affords higher product yield and lower waste production compared to the traditional hydrothermal synthesis. However, the as-made zeolites usually present blocky aggregation states, limiting their mass transfer and exposure of active sites in catalytic applications. Herein, highly dispersed nanosized hierarchical Beta zeolites with varied Si/Al ratios were prepared via steam-assisted crystallization from ball-milled solid raw materials. Thanks to the sufficient mixing of solid raw materials and favorable migration of solid mixture, nanosized Beta zeolites are obtained that are assembled from nanoparticles (∼15 nm) and possess abundant interconnected intraparticle mesopores. The strategy can also be extended to synthesize nanosized hierarchical ZSM-5 zeolites. The as-prepared Beta zeolite (Si/Al = 10) exhibits outstanding catalytic performance in conversion of lactic acid to lactide (as high as 77.5% in yield). This work provides avenues for simple and cost-efficient synthesis of highly dispersed nanosized hierarchical zeolites, promising their important catalytic applications.

Unveiling Secondary-Ion-Promoted Catalytic Properties of Cu-SSZ-13 Zeolites for Selective Catalytic Reduction of NOx.

The incorporation of secondary metal ions into Cu-exchanged SSZ-13 zeolites could improve their catalytic properties in selective catalytic reduction of NOx with ammonia (NH3-SCR), but their essential roles remain unclear at the molecular level. Herein, a series of Cu-Sm-SSZ-13 zeolites have been prepared by ion-exchanging Sm ions followed by Cu ions, which exhibit superior NH3-SCR performance. The NO conversion of Cu-Sm-SSZ-13 is nearly 10% higher than that of conventional Cu-SSZ-13 (175-250 °C) after hydrothermal ageing, showing an enhanced low-temperature activity. The Sm ions are found to occupy the six-membered rings (6MRs) of SSZ-13 by X-ray diffraction Rietveld refinement and aberration-corrected scanning transmission electron microscopy. The Sm ions at 6MRs can facilitate the formation of more active [ZCu2+(OH)]+ ions at 8MRs, as revealed by temperature-programmed reduction of hydrogen. X-ray photoelectron spectroscopy and density functional theory (DFT) calculations indicate that there exists electron transfer from Sm3+ to [ZCu2+(OH)]+ ions, which promotes the activity of [ZCu2+(OH)]+ ions by decreasing the activation energy of the formation of intermediates (NH4NO2 and H2NNO). Meanwhile, the electrostatic interaction between Sm3+ and [ZCu2+(OH)]+ results in a high-reaction energy barrier for transforming [ZCu2+(OH)]+ ions into inactive CuOx species, thus enhancing the stability of [ZCu2+(OH)]+ ions. The influence of the ion-exchanging sequence of Sm and Cu ions into SSZ-13 is further investigated by combining both experiments and theoretical calculations. This work provides a mechanistic insight of secondary ions in regulating the distribution, activity, and stability of Cu active sites, which is helpful for the design of high-performance Cu-SSZ-13 catalysts for the NH3-SCR reaction.

A new deep learning method for displacement tracking from ultrasound RF signals of vascular walls.

It is necessary to monitor the mechanical properties of arteries which directly related to cardiovascular diseases (CVDs) in the early stages. In this study, we proposed a new method based on deep learning (DL) to track the displacement of the vessel wall from the ultrasound radio-frequency (RF) signals, which is a key technique to achieve quantitative measurement of vascular biomechanics. In comparison with traditional method, both results on simulation and experimental carotid artery data demonstrated that the DL method has higher accuracy for motion tracking of artery walls. Hence, the DL method can be widely applied so that can predict the early pathology of cardiovascular system.

[Acupoint selection rules of neurogenic dysphagia treated with acupuncture and moxibustion in ancient times].

Acupoint selection rules of neurogenic dysphagia treated with acupuncture and moxibustion from pre-Qin to late Qing Dynasty in Chinese Medical Classics were analyzed based on data mining. The literature regarding acupuncture and moxibustion for neurogenic dysphagia was searched and screened according to the inclusion and exclusion criteria in Chinese Medical Classics (5th Edition), the prescriptions were extracted according to the principle of acupoint extraction.The SPSS 21.0 and Clementine 12.0 were used to perform the cluster analysis and association rule analysis.A total of 191 acupuncture and moxibustion prescriptions were screened and extracted，including 45 acupoints. The top 5 acupoints of acupuncture and moxibustion for neurogenic dysphagia in frequency were Jiache (ST 6), Dicang (ST 4), Lieque (LU 7), Lianquan (CV 23), Shuigou (GV 26). The most involved meridians were the stomach meridian, the governor vessel and the conception vessel. The main acupoints were distributed in the scalp face neck and upper limbs. The most frequently used specific acupoints was crossing points,next was eight confluence points. There were 11 acupoint combinations with strong association according to the association rule analysis, and the top one acupoint combination was Hegu (LI 4)-Jiache (ST 6). There were 9 acupoint cluster groups according to the cluster analysis. Hegu (LI 4), Jiache (ST 6), Dicang (ST 4), Shuigou (GV 26) and Chengjiang (CV 24) were core acupoints for neurogenic dysphagia treated with acupuncture and moxibustion in ancient times, besides，selecting proximal and distal acupoints and selecting acupoints according to symptoms were emphasized.

[Acupuncture for dysarthria: systematic review].

OBJECTIVE: To systematically evaluate the clinical efficacy of acupuncture for dysarthria, and to explore the rules of acupoints selection for dysarthria. METHODS: The clinical randomized control trial literature regarding acupuncture for dysarthria published before January of 2018 were searched in databases, including CNKI, Wanfang, VIP, CBM, PubMed, Ebsco, Science Direct and Cochrane Library. The information of included studies was extract and the quality was assessed. The Meta analysis was performed by using RevMan 5.3 software. The frequency of acupoints was calculated by using Excel software to analyzed the rules of acupoints selection. RESULTS: Totally 21 papers were included, involving 1651 patients. The pooled effects of clinical efficacy: heterogeneity test P =0.74, I 2=0%, OR =6.36, 95% CI: 4.55, 8.88, Z =10.84 (P<0.01), indicating the efficacy in the treatment group was significantly higher than that in the control group. The pooled effects of the symptom score in Frenchay scale: heterogeneity test P =0.56, I 2=0%, WMD =3.20, 95% CI: 1.38, 5.02, Z =3.45 (P<0.01), indicating the efficacy in the treatment group was significantly higher than that in the control group. The acupoints with frequency of more than 5 times were Fengchi (GB 20), Yuye (EX-HN 13), Jinjin (EX-HN 12), Lianquan (CV 23), Baihui (GV 20), tongue-three needles and Yamen (GV15). The meridians with frequency of more than 5 times were the extra channels, governor vessel, gallbladder channel, conception vessel and stomach channel. CONCLUSION: The clinical efficacy of acupuncture combined with speech training/regular treatment is significantly superior to that of control group (speech training, medication, regular treatment); acupuncture is safe and effective for dysarthria; the majority of selected acupoint is local acupoints around tongue, throat and neck, as well as extra points and empirical points. However, high-quality randomized controlled trials with large sample sizes are still needed to provide further evidence.

Synthesis and Characterization of Eu3+-Doped CdS Quantum Dots by a Single-Step Aqueous Method.

Eu3+-doped CdS quantum dots (QDs) are successfully synthesized through a straightforward single-pot process in aqueous solution using thioglycolic acid as the capping ligand. The structure, shape, and spectral properties of the QDs are investigated. The obtained CdS:Eu3+ QDs exhibit cubic structures with good crystallinity and approximately sphere-like shapes about 4 nm in diameter. The CdS QDs manifest a broadband emission peak at 600 nm and enhanced Photoluminescence (PL) emission intensity after doping with Eu3+ ions. Given the strong PL intensity and good chromaticity of the sulfide-based QDs, they have potential use in doping rare-earth ions.

Membrane lipid composition regulates tubulin interaction with mitochondrial voltage-dependent anion channel.

Elucidating molecular mechanisms by which lipids regulate protein function within biological membranes is critical for understanding the many cellular processes. Recently, we have found that dimeric αß-tubulin, a subunit of microtubules, regulates mitochondrial respiration by blocking the voltage-dependent anion channel (VDAC) of mitochondrial outer membrane. Here, we show that the mechanism of VDAC blockage by tubulin involves tubulin interaction with the membrane as a critical step. The on-rate of the blockage varies up to 100-fold depending on the particular lipid composition used for bilayer formation in reconstitution experiments and increases with the increasing content of dioleoylphosphatidylethanolamine (DOPE) in dioleoylphosphatidylcholine (DOPC) bilayers. At physiologically low salt concentrations, the on-rate is decreased by the charged lipid. The off-rate of VDAC blockage by tubulin does not depend on the lipid composition. Using confocal fluorescence microscopy, we compared tubulin binding to the membranes of giant unilamellar vesicles (GUVs) made from DOPC and DOPC/DOPE mixtures. We found that detectable binding of the fluorescently labeled dimeric tubulin to GUV membranes requires the presence of DOPE. We propose that prior to the characteristic blockage of VDAC, tubulin first binds to the membrane in a lipid-dependent manner. We thus reveal a new potent regulatory role of the mitochondrial lipids in control of the mitochondrial outer membrane permeability and hence mitochondrial respiration through tuning VDAC sensitivity to blockage by tubulin. More generally, our findings give an example of the lipid-controlled protein-protein interaction where the choice of lipid species is able to change the equilibrium binding constant by orders of magnitude.

Bacteria-induced static batch fungal fermentation of the diterpenoid cyathin A(3), a small-molecule inducer of nerve growth factor.

Cyathin A(3), produced by the fungus Cyathus helenae, is a member of the cyathane family of diterpene natural products. While many of the cyathanes display antibacterial/antimicrobial activity or have cytotoxic activity against human cancer cell lines, their most exciting therapeutic potential is derived from their ability to induce nerve growth factor (NGF) release from glial cells, making the cyathanes attractive lead molecules for the development of neuroprotective therapeutics to prevent/treat Alzheimer's disease. To investigate if cyathin A(3) has NGF-inducing activity, we set out to obtain it using published C. helenae bench-scale fungal fermentations. However, to overcome nonproducing fermentations, we developed an alternative, bacteria-induced static batch fermentation approach to the production of cyathin A(3), as described in this report. HPLC, UV absorption spectra, and mass spectrometry identify cyathin A(3) in fungal fermentations induced by the timely addition of Escherichia coli K12 or Bacillus megabacterium. Pre-filtration of the bacterial culture abolishes cyathin A(3) induction, suggesting that bacteria-associated media changes or physical interaction between the fungus and bacteria underlie the induction mechanism. Through alteration of incubation conditions, including agitation, the timing of induction, and media composition, we optimized the fermentation to yield nearly 1 mg cyathin A(3)/ml media, a sixfold increase over previously described yields. Additionally, by comparison of fermentation profiles, we reveal that cyathin A(3) biosynthesis is regulated by carbon catabolite repression. We have used an enzyme-linked immunosorbent assay to illustrate that cyathin A(3) induces NGF release from cultured glial cells, and therefore cyathin A(3) warrants further examination in the development of neuroprotective therapeutics.