Atomic Ruthenium-Promoted Cadmium Sulfide for Photocatalytic Production of Amino Acids from Biomass Derivatives.

Amino acids are the building blocks of proteins and are widely used as important ingredients for other nitrogen-containing molecules. Here, we report the sustainable production of amino acids from biomass-derived hydroxy acids with high activity under visible-light irradiation and mild conditions, using atomic ruthenium-promoted cadmium sulfide (Ru1/CdS). On a metal basis, the optimized Ru1/CdS exhibits a maximal alanine formation rate of 26.0 molAla ⋅ gRu -1 ⋅ h-1, which is 1.7 times and more than two orders of magnitude higher than that of its nanoparticle counterpart and the conventional thermocatalytic process, respectively. Integrated spectroscopic analysis and density functional theory calculations attribute the high performance of Ru1/CdS to the facilitated charge separation and O-H bond dissociation of the α-hydroxy group, here of lactic acid. The operando nuclear magnetic resonance further infers a unique "double activation" mechanism of both the CH-OH and CH3-CH-OH structures in lactic acid, which significantly accelerates its photocatalytic amination toward alanine.

Non-Noble FeCrOx Bimetallic Nanoparticles for Efficient NH3 Decomposition.

Ammonia has the advantages of being easy to liquefy, easy to store, and having a high hydrogen content of 17.3 wt%, which can be produced without COx through an ammonia decomposition using an appropriate catalyst. In this paper, a series of FeCr bimetallic oxide nanocatalysts with a uniform morphology and regulated composition were synthesized by the urea two-step hydrolysis method, which exhibited the high-performance decomposition of ammonia. The effects of different FeCr metal ratios on the catalyst particle size, morphology, and crystal phase were investigated. The Fe0.75Cr0.25 sample exhibited the highest catalytic activity, with an ammonia conversion of nearly 100% at 650 °C. The dual metal catalysts clearly outperformed the single metal samples in terms of their catalytic performance. Besides XRD, XPS, and SEM being used as the means of the conventional characterization, the local structural changes of the FeCr metal oxide catalysts in the catalytic ammonia decomposition were investigated by XAFS. It was determined that the Fe metal and FeNx of the bcc structure were the active species of the ammonia-decomposing catalyst. The addition of Cr successfully prevented the Fe from sintering at high temperatures, which is more favorable for the formation of stable metal nitrides, promoting the continuous decomposition of ammonia and improving the decomposition activity of the ammonia. This work reveals the internal relationship between the phase and structural changes and their catalytic activity, identifies the active catalytic phase, thus guiding the design and synthesis of catalysts for ammonia decomposition, and excavates the application value of transition-metal-based nanocomposites in industrial catalysis.

Leveraging Chiral Zr(IV)-Based Metal-Organic Frameworks To Elucidate Catalytically Active Rh Species in Asymmetric Hydrogenation Reactions.

One of the most widely employed strategies to produce chiral molecules involves the asymmetric hydrogenation of functionalized olefins using rhodium catalysts. Despite their excellent performance, the exact identity of the active Rh species is still ambiguous as each site may plausibly feature one or two phosphorus ligands. In this work, we used a sequential postsynthetic modification approach to successfully incorporate single-site Rh species into a zirconium-based metal-organic framework comprised of chiral spinol-based ligands. These Rh species feature one phosphorus ligand per Rh, which contrasts with the molecular analogue that contains two phosphorus ligands per Rh site. Following extensive characterization of the Rh-monophosphorus material using techniques including solid-state NMR and extended X-ray absorption fine-structure (EXAFS) spectroscopy, we studied their catalytic performance in the asymmetric hydrogenations of enamides and α-dehydroamino acid esters and observed excellent yields and enantioselectivities (up to 99.9% ee). Notably, the Rh-monophosphorus catalyst is 5 times more active than the homogeneous Rh-biphosphorus control, which we attributed to the higher activity of the single-site Rh-monophosphorus species and the confined MOF cavities that can enrich reactants. In addition, we observed a unique topology-dependent behavior in which linker expansion leads to the formation of a novel Zr-MOF with a distinct 4,8-connected net that cannot be phosphorylated, presumably due to intense tensile strain and steric repulsion present within this framework. Finally, we demonstrate the utility of this single-site Rh-monophosphorus catalyst in the gram-scale synthesis of (R)-cinacalcet hydrochloride, a first-in-class drug in the therapy of secondary hyperparathyroidism and parathyroid carcinoma, with 99.1% ee.

Temperature-Dependent CO2 Electroreduction over Fe-N-C and Ni-N-C Single-Atom Catalysts.

Reaction temperature is an important parameter to tune the selectivity and activity of electrochemical CO2 reduction reaction (CO2 RR) due to different thermodynamics of CO2 RR and competitive hydrogen evolution reaction (HER). In this work, temperature-dependent CO2 RR over Fe-N-C and Ni-N-C single-atom catalysts are investigated from 303 to 343 K. Increasing the reaction temperature improves and decreases CO Faradaic efficiency over Fe-N-C and Ni-N-C catalysts at high overpotentials, respectively. CO current density over Fe-N-C catalyst increases with temperature, then gets into a plateau at 323 K, finally reaches the maximum value of 185.8 mA cm-2 at 343 K. While CO current density over Ni-N-C catalyst achieves the maximum value of 252.5 mA cm-2 at 323 K, and then drops significantly to 202.9 mA cm-2 at 343 K. Temperature programmed desorption results and density functional theory calculations reveal that the difference of temperature-dependent variation on CO Faradaic efficiency and current density between Fe-N-C and Ni-N-C catalysts results from the varied adsorption strength of key reaction intermediates during CO2 RR.

Unique structure of active platinum-bismuth site for oxidation of carbon monoxide.

As the technology development, the future advanced combustion engines must be designed to perform at a low temperature. Thus, it is a great challenge to synthesize high active and stable catalysts to resolve exhaust below 100 °C. Here, we report that bismuth as a dopant is added to form platinum-bismuth cluster on silica for CO oxidation. The highly reducible oxygen species provided by surface metal-oxide (M-O) interface could be activated by CO at low temperature (~50 °C) with a high CO2 production rate of 487 µmolCO2·gPt-1·s-1 at 110 °C. Experiment data combined with density functional calculation (DFT) results demonstrate that Pt cluster with surface Pt-O-Bi structure is the active site for CO oxidation via providing moderate CO adsorption and activating CO molecules with electron transformation between platinum atom and carbon monoxide. These findings provide a unique and general approach towards design of potential excellent performance catalysts for redox reaction.

Effect of extruded starches on the structure, farinograph characteristics and baking behavior of wheat dough.

Extruded wheat starch (ES) was obtained by a single-screw extruder to determine its effect on the farinograph, structural properties and baking behaviors of wheat dough. XRD analysis showed that increasing extrusion temperature made the crystalline peaks less pronounced due to the partial gelatinization. In terms of FTIR results, the molecular order of extruded starch was lower than that of native starch. The dough development time was decreased from 3.2 min to 2.7 min while the stability time was increased from 14.4 min to 15.5 min, as 70 ES were added. It was accompanied with increasing levels of α-helix and ß-turn transferred from the decreased content of random coil and ß -sheet. These effects in bread were to increase loaf volume and reduced loaf hardness. These results indicated that extruded starch had a good potential for producing a high-quality bread.

Enhancing CO2 Electroreduction to Methane with a Cobalt Phthalocyanine and Zinc-Nitrogen-Carbon Tandem Catalyst.

Developing copper-free catalysts for CO2 conversion into hydrocarbons and oxygenates is highly desirable for electrochemical CO2 reduction reaction (CO2 RR). Herein, we report a cobalt phthalocyanine (CoPc) and zinc-nitrogen-carbon (Zn-N-C) tandem catalyst for CO2 RR to CH4 . This tandem catalyst shows a more than 100 times enhancement of the CH4 /CO production rate ratio compared with CoPc or Zn-N-C alone. Density functional theory (DFT) calculations and electrochemical CO reduction reaction results suggest that CO2 is first reduced into CO over CoPc and then CO diffuses onto Zn-N-C for further conversion into CH4 over Zn-N4 site, decoupling complicated CO2 RR pathway on single active site into a two-step tandem reaction. Moreover, mechanistic analysis indicates that CoPc not only generates CO but also enhances the availability of *H over adjacent N sites in Zn-N4 , which is the key to achieve the high CH4 production rate and understand the intriguing electrocatalytic behavior which is distinctive to copper-based tandem catalysts.

[Study on the mechanism of autologous platelet-rich gel to treat the refractory diabetic dermal ulcers].

OBJECTIVE: To investigate the mechanism of autologous platelet-rich gel (APG)in the treatment of refractory diabetic dermal ulcers. METHODS: After the treatment of refractory diabetic dermal ulcers with APG at 0, 3, 6, 9, 15 days, the protein levels of PDGF-BB, VEGF, IGF-1, EGF and TGF-beta1 in the granulation tissue were detected by ELISA, while the dimensions of ulcer area were measured at the same time. RESULTS: The areas of ulcers were obviously reduced at the third and fifteen day after APG treatment (P < 0.05). The concentrations of these 5 growth factors in the granulation tissue were began to increase after 3 days treatment, the peak of PDGF-BB emerged at the third day (P < 0.05), and the peaks of VEGF, IGF-1, TGF-beta1 were found at the ninth day (P < 0.05). The concentration of VEGF increased 2.1-fold, IGF-1 increased 1.95-fold, EGF increased 1.75-fold, PDGF-BB increased 1.89-fold and TGF-beta1 increased 1.67-fold. CONCLUSION: The expression of multiple growth factors are increased in granulation tissue of refractory diabetic dermal ulcers after the treatment of APG,which might be one of the mechanism of APG to treat refractory diabetic dermal ulcer.

[The preliminary application of autologous platelet-rich gel used to treat refractory diabetic dermal ulcer].

OBJECTIVE: To assess the effectiveness and security of autologous platelet-rich gel (APG) in the treatment of refractory diabetic dermal ulcers. METHODS: Thirteen diabetic patients with refractory skin lesions were enrolled for this study, and APG was produced by platelet (PLT)-rich plasma (PRP) with thrombin and calcium gluconate. APG treatment consisted of wound dressed with APG, followed by topical washing and cleaning. The APG was then covered with Vaseline gauze and left for 48 to 72 hours, after which the wounds were treated conventionally until the next PLT-gel treatment. The clinical endpoints of the study were the healing rate. RESULTS: A total of 13 patients entered the pilot study. There were no drop-outs in the study. 69.2% ulcers were cured, and especially the ulcer areas were reduced significantly in the first 3 weeks; no adverse reactions were observed. CONCLUSION: Topical therapy with APG may be considered as an effective adjuvant method to treating refractory diabetic dermal ulcer.