Template Synthesis of Cyclometalated Macrocycle Iridium(III) Complexes Based on Photoinduced C-N Cross-Coupling Reactions In Situ.

The synthesis of metal macrocycle complexes holds paramount importance in coordination and supramolecular chemistry. Toward this end, we report a new, mild, and efficient protocol for the synthesis of cyclometalated macrocycle Ir(III) complexes: [Ir(L1)](PF6) (1), [Ir(L2)](PF6) (2), and [Ir(L3)](PF6) (3), where L1 presents 10,17-dioxa-3,6-diaza-2(2,8),7(8,2)-diquinolina-1,8(1,4)-dibenzenacyclooctadecaphane, L2 is 10,13,16,19,22,25-hexaoxa-3,6-diaza-2(2,8),7(8,2)-diquinolina-1,8(1,4)-dibenzenacyclohexacosaphane, and L3 is 4-methyl-10,13,16,19,22,25-hexaoxa-3,6-diaza-2(2,8),7(8,2)-diquinolina-1,8(1,4)-dibenzenacyclohexacosaphane. This synthesis involves the preassembly of two symmetric 2-phenylquinoline arms into C-shape complexes, followed by cyclization with diamine via in situ interligand C-N cross-coupling, employing a metal ion as a template. Moreover, the synthetic yield of these cyclometalated Ir(III) complexes, tethered by an 18-crown-6 ether-like chain, is significantly enhanced in the presence of K+ ion as a template. The resultant cyclometalated macrocycle Ir(III) complexes exhibit high stability, efficient singlet oxygen generation, and superior catalytic activity for the aerobic selective oxidation of sulfides into sulfoxides under visible light irradiation in aqueous media at room temperature. The photocatalyst 2 demonstrates recyclability and can be reused at least 10 times without a significant loss of catalytic activity. These results unveil a new and complementary approach to the design and in situ synthesis of cyclometalated macrocycle Ir(III) complexes via a mild interligand-coupling strategy.

Influence of Acetone and Primer on Strength and Ductility of Chlorinated Poly(vinyl chloride).

Primer is widely used to prepare bonding of chlorinated poly(vinyl chloride) (CPVC) pipe. The study examined the influences of primer and its major component, acetone, on CPVC's mechanical properties. Two types of CPVC product, sheet and pipe, were used in the mechanical testing. Sheet specimens were immersed in acetone or primer for 40 and 10 min, respectively, i.e., the maximum allowable time without mass loss, and then dried in air before the mechanical testing. Pipe (ring) specimens were treated either through immersion in acetone or primer for 30 min or in contact with these solvents locally on the inner surface for 2.5 h, and then air dried for 10.5 days before the mechanical testing. Results showed that CPVC's strength decreased after the absorption of these solvents, and air dry could remove acetone but not completely primer. The study also showed that pipe specimens by local contact with primer could generate brittle fracture. In view that sheet specimens always fractured in a ductile manner, brittle fracture of the pipe specimens could not be caused by CPVC degradation. Rather, strength decrease in the local region could provide a plausible explanation for the brittle fracture behavior, though further investigation is needed.

Epiphytic microbiota source stimulates the fermentation profile and bacterial community of alfalfa-corn mixed silage.

The epiphytic microbiota source on plants plays a crucial role in the production of high-quality silage. To gain a better understanding of its contribution, the microbiota of alfalfa (M1C0), corn (M0C1) and the resulting mixture (M1C1) was applied in alfalfa-corn mixed silage production system. M1C0 decreased ammonia-N levels in terms of total nitrogen (57.59-118.23 g/kg TN) and pH (3.59-4.40) values (p < 0.01), which increased lactic acid (33.73-61.89 g/kg DM) content (p < 0.01). Consequently, this resulted in higher residual water-soluble carbohydrate (29.13-41.76 g/kg DM) and crude protein (152.54-167.91 g/kg DM) contents, as well as lower NDF (427.27 g/kg DM) and ADF (269.53 g/kg DM) contents in the silage compared to M1C1- and M0C1-treated samples. Moreover, M1C0 silage showed significantly higher bacterial alpha diversity indices (p < 0.05), including the number of observed species and Chao1 and Shannon diversity indices, at the later stages of ensiling. Lactobacillus, Kosakonia and Enterobacter were the dominant bacterial species in silages, with a relative abundance of >80%. However, the abundance of Lactobacillus amylovorus in M0C1- and M1C1-treated silage increased (p < 0.01) in the late stages of ensiling. These findings confirmed that the epiphytic microbiota source exerts competitive effects during anaerobic storage of alfalfa-corn mixed silage.

Switching the Photoreactions of Ir(III) Diamine Complexes between C-N Coupling and Dehydrogenation under Visible Light Irradiation.

The selective photoreactions under mild conditions play an important role in synthetic chemistry. Herein, efficient and mild protocols for switching the photoreactions of Ir(III)-diamine complexes between the interligand C-N coupling and dehydrogenation are developed in the presence of O2 in EtOH solution. The photoreactions of achiral diamine complexes rac-[Ir(L)2(dm)](PF6) (L is 2-phenylquinoline or 2-(2,4-difluorophenyl)quinoline, dm is 1,2-ethylenediamine, 1,2-diaminopropane, 2-methyl-1,2-diamino-propane, or N,N'-dimethyl-1,2-ethylenediamine) are competitive in the oxidative C-N coupling and dehydrogenation at room temperature, which can be switched into the interligand C-N coupling reaction at 60 °C, affording hexadentate complexes in good to excellent yields, or the dehydrogenative reaction in the presence of a catalytic amount of TEMPO as an additive, affording imine complexes. Mechanism studies reveal that 1O2 is the major reactive oxygen species, and metal aminyl is the key intermediate in the formation of the oxidative C-N coupling and imine products in the photoreaction processes. These will provide a new and practical protocol for the synthesis of multidentate and imine ligands in situ via the postcoordinated strategy under mild conditions.

Effect of epiphytic microflora after aerobic enrichment and reconstitution on fermentation quality and microbial community of corn stalk silage and Pennisetum sinese silage.

Introduction: The objective of this study was to evaluate the effects of enrichment and reconstitution of the forage epiphytic microflora on the fermentation quality, chemical composition, and bacterial community composition of corn stalk and Pennisetum sinese silages. Methods: The forage juice of fresh corn stalk and P. sinese were collected, diluted by gradient (10-1 to 10-5), and aerobically incubated to enrich and reconstitute the epiphytic microflora. Fresh corn stalk and P. sinese were ensiled for 3, 15, and 45 days after inoculation with either the original (D0) pre-incubated juices, or 10-1 (D1), 10-3 (D3), or 10-5 (D5) diluted and pre-incubated juices. Results: The lowest pH was found in the D3 treatment of the corn stalk silage. In P. sinese silage, the hemicellulose content of D3 and D5 treatments was 9.50 and 11.81% lower than that of D0 treatment (P < 0.05). In corn stalk silage, the neutral detergent fiber content was significantly lower in the D3 treatment than in the other treatments (P < 0.05). Both corn stalk and P. sinese silages exhibited a high abundance of Enterobacter during ensiling, resulting in high levels of acetic acid. Conclusion: Although the dilution and enrichment of the epiphytic microflora did not lead to full lactic acid fermentation, these pre-treatments were found to alter the microbial metabolites and chemical composition of the silage. These results provide a new perspective on the production of pre-fermented silage inoculant.

Effect of lactic acid bacteria, yeast, and their mixture on the chemical composition, fermentation quality, and bacterial community of cellulase-treated Pennisetum sinese silage.

The present study investigated the effects of Lentilactobacillus buchneri, Saccharomyces cerevisiae, and a mixture of the two on the cellulose degradation and microbial community of cellulase-treated Pennisetum sinese (CTPS) during biological pretreatment. The CTPS was stored without additives (CK) or with L. buchneri (L), yeast (Y, S. cerevisiae), and their mixture (LY) under anaerobic conditions for 60 days. All inoculants enhanced the anaerobic fermentation of CTPS. In relative to L, inoculations with Y and LY decreased the cellulose level of fermented-CTPS by 8.90 ~ 17.13%. Inoculation with L inhibited the growth of Weissella cibaria during anaerobic storage. However, inoculations with LY increased the relative abundance of the homofermentative bacterium Lactiplantibacillus plantarum by 6.04%. Therefore, inoculating S. cerevisiae reduced the adverse effects of L. buchneri-stimulated fermentation on cellulose degradation by altering the bacterial community during anaerobic storage of P. sinese. This work provides a new insight for the subsequent anaerobic digestion of P. sinese.

Recanalization of thrombosed aneurysmal hemodialysis arterovenous fistulas using a hybrid technique based on data from a single center.

OBJECTIVE: To explore the technical specifications and clinical outcomes of thrombosed aneurysmal haemodialysis arteriovenous fistula (AVF) treated with ultrasound-guided percutaneous transluminal angioplasty combined with minimal aneurysmotomy. METHODS: This case series study included 11 patients who had thrombosed aneurysmal AVF and underwent salvage procedures over a 13-month period. All procedures were performed under duplex guidance. Minimal aneurysmotomy was performed, along with manual thrombectomy and thrombolytic agent infusion, followed by angioplasty to macerate the thrombus and sufficiently dilate potential stenoses. A successful procedure was defined as immediate restoration of flow through the AVF. RESULTS: The 11 patients (four males and seven females) had a mean age of 49.6 years ± 11.9 years. Six patients (54.5%) had two or more aneurysms. The mean aneurysm maximal diameter was 21.5 mm (standard deviation: ± 5.0 mm), and the mean thrombus length was 12.9 cm (8-22 cm). Ten (83.3%) of the 12 procedures were technically successful. The mean duration of operation was 150.9 minutes (standard deviation: ± 34.2 minutes), and mean postoperative AVF blood flow was 728.6 ml/min (standard deviation: ± 53.7 mi/min). The resumption of hemodialysis was successful in all 11 cases, with a clinical success rate of 100%. The primary patency rates were 90.0% and 75.0% at three and four months over a mean follow-up time of 6.3 months (3-12 months). The secondary patency rates were 90.4% at three and four months. CONCLUSION: A hybrid approach combining ultrasound-guided percutaneous transluminal angioplasty and minimal aneurysmotomy might be a safe and effective method for thrombosed aneurysmal AVF salvage.

Effects of ambient temperature and available sugar on bacterial community of Pennisetum sinese leaf: An in vitro study.

The present in vitro study investigated the effects of temperature and available sugar on the bacterial community of Pennisetum sinese leaf during fermentation. P. sinese leaves were cultured in MRS broth containing 0.4 and 1.6 g sugar and incubated at 25°C and 45°C for 9, 18, and 36 h. The results showed that the dominant phyla during sugar fermentation were Firmicutes, followed by Proteobacteria and Bacteroidetes. Compared to a low incubation temperature (25°C), a high incubation temperature (45°C) decreased the relative abundances of Exiguobacterium and Acinetobacter and increased those of Bacillus and Paenibacillus. Leaf samples incubated at 25°C showed higher bacterial alpha diversity indices than those incubated at 45°C. Principal coordinate analysis revealed that the bacterial community structure was altered by the high incubation temperature. Sugar concentration of 1.6 g/50 ml increased the relative abundances of Bacillus and Klebsiella but decreased those of Paenibacillus and Serratia as compared to sugar concentration of 0.4 g/50 ml. pH was the primary factor that influenced the succession of bacterial communities during sugar fermentation in P. sinese leaves. In conclusion, ambient temperatures (25°C and 45°C) and high sugar concentration restructured the bacterial communities on P. sinese leaves by facilitating the dominance of Bacillus and Paenibacillus. This study provided insights into the mechanisms by which bacterial communities on P. sinese leaves are enriched.

Effects of Additives on Silage Fermentation Characteristic and In Vitro Digestibility of Perennial Oat at Different Maturity Stages on the Qinghai Tibetan.

To effectively use local grass resources to cover the winter feed shortage on the Qinghai-Tibetan Plateau, the silage fermentation and in vitro digestibility of perennial oat (Helictotrichonvirescens Henr.) were investigated. Perennial oat was harvested at the heading/flowering stage, wilted under sunny conditions, chopped, vacuumed in small bag silos, and stored at ambient temperatures (5-15 °C) for 60 days. The silages were treated without (CK) or with local lactic acid bacteria (LAB) inoculant (IN1), commercial LAB inoculant (IN2), and sodium benzoate (BL). Control silages of perennial oat at early heading stage showed higher (p < 0.05) lactate and acetate contents and lower (p < 0.05) final pH, butyrate, and ammonia-N contents than those at the flowering stage. High levels of dry matter recovery (DMR) and crude protein (CP) were observed in IN1- and BL-treated silages, with high in vitro gas production and dry matter digestibility. Compared to CK, additives increased (p < 0.05) aerobic stability by inhibiting yeasts, aerobic bacteria, and coliform bacteria during ensiling. In particular, the local LAB inoculant increased (p < 0.05) concentrations of lactate, acetate and propionate, and decreased concentrations of butyrate and ammonia-N in silages. This study confirmed that local LAB inoculant could improve the silage quality of perennial oat, and this could be a potential winter feed for animals such as yaks on the Qinghai Tibetan Plateau.

Robust Yellow-Violet Pigments Tuned by Site-Selective Manganese Chromophores.

The rational design of multifunctional inorganic pigments relies on the manipulation of ionic valence and local surroundings of a chromophore in structurally and chemically habitable hosts. To date, the development of environmentally benign and intense violet/purple pigments is still a challenge. Here we report a family of A3-xMnxTeO6 and A3-2xMnxLixTeO6 (A = Zn, Mg; x = 0.01-0.15) pigments colored by site-selective Mn2+O4 yellow and Mn3+O5-6 violet chromophores. Zn2.9Mn0.1TeO6 is intense bright yellow, comparable with commercial BiVO4, and has better near-infrared reflectivity (∼89%) in comparison to commercial TiO2. The codoped Li+ "activator" generates holes and charge-balanced Mn3+ (Mn3+O5-6), realizing a color transformation from yellow to the bright violet pigments of A3-2xMnxLixTeO6. The most vivid Mg2.8Mn0.1Li0.1TeO6 is probably the best violet pigment known to date, exhibits excellent chemical and thermodynamic stability, and demonstrates pressure-dependent stability up to 5-7 GPa, before a (reversible) phase transition to pink. Theoretical calculations revealed the correlation between site-preference occupancy and chromophore motifs and predicted a wide color gamut of pigments in Zn3TeO6-hosted 3d transition-metal ions other than manganese.

Vertically aligned FeOOH nanosheet arrays on alkali-treated nickel foam as highly efficient electrocatalyst for oxygen evolution reaction.

The adverse effects caused by global climate warming continue to be a great impetus to develop electrocatalytic water splitting technology for hydrogen source production. However, there is an urgent necessity but it is still a significant challenge to explore electrocatalysts with excellent performance, low cost, and environmental benignity for expediting the oxygen evolution reaction (OER) owing to the sluggish reaction kinetics. Fe-based materials, especially FeOOH, have great potential as OER electrocatalysts but suffers from poor electrical conductivity. Herein, we rationally designed and successfully synthesized FeOOH nanosheet arrays supported on alkali-treated nickel foam (FeOOH NSAs/ATNF) and applied it as an electrocatalyst toward OER. The FeOOH NSAs/ATNF catalyst exhibited outstanding performance with small overpotential, fast kinetics and superior stability in alkaline medium. Our research opens up a facile and effective approach to develop cost-effective and high-performance electrocatalysts for energy conversion, especially for these Fe-based materials with poor electrical conductivity.

Hierarchical iron-doped CoP heterostructures self-assembled on copper foam as a bifunctional electrocatalyst for efficient overall water splitting.

A bifunctional electrocatalyst with peculiarly hierarchical snowflake-like iron-doped CoP heterostructures self-assembled on copper foam (CoFeP/CF) was synthesized via a facile hydrothermal-phosphidation pathway. The excellent electrochemical performance of CoFeP/CF can be attributed to the synergistic effect of cobalt and iron atoms, tuneful interaction between metal atoms and phosphorus, and the large electrochemical active surface area origined from its peculiarly hierarchical snowflake-like heterostructures with high surface roughness. With the small Tafel slope values (of 73.0 mV dec-1 for OER and 90.4 mV dec-1 for HER), CoFeP/CF demands the diminutive overpotentials (of 277.9 mV for OER and 152.6 mV for HER) to desire the current density of 50 mA cm-2 in alkaline electrolyte. Furthermore, CoFeP/CF exhibits outstanding electrochemical performance for the overall water splitting with the cell potential of 1.495 V to attain 10 mA cm-2 in a two-electrode cell.

Synthesis of Metal Phosphide Nanoparticles Supported on Porous N-Doped Carbon Derived from Spirulina for Universal-pH Hydrogen Evolution.

Transition metal phosphides (TMPs) are regarded as highly active electrocatalysts for the hydrogen evolution reaction (HER). However, traditional synthetic routes usually use expensive and dangerous precursors as P donors. The development of a low-cost and ecofriendly method for the synthesis of TMPs is significant for sustainable energy development. Herein, cobalt phosphides anchored on or embedded in a spirulina-derived porous N-doped carbon matrix (Co2 P/NC) was fabricated by two-step hydrothermal treatment and carbonization method, which utilized the intrinsic C, N, and P of biomass cleverly as the sources of C, N, and P, respectively. As a result of the high surface area and porosity that enhance the mass-transfer dynamics, Co2 P/NC shows good electrocatalytic activity at all pH values in the HER. This work not only provides a facile and effective method for the fabrication of TMP nanoparticles loaded onto carbon materials but also opens a new strategy for the utilization of the intrinsic ingredients of biomass for the preparation of other functional electrocatalysts.

Nitrogen and phosphorus dual-doping carbon shells encapsulating ultrafine Mo2C particles as electrocatalyst for hydrogen evolution.

Electrochemical hydrogen evolution reaction (HER) from water splitting is a promising way to promote the utilization of renewable energy. Designing and fabricating electrocatalysts with low cost, high catalytic activity and robust stability is desirable. In response, we prepared carbon shells encapsulating ultrafine ß-Mo2C nanoparticles with N and P dual-doping as advanced electrocatalyst used for HER in both acidic and alkaline mediums. This paper gives a discussion on element doping and porosity which have influence on the HER performance. As introducing heteroatoms into carbon matrix to create active sites and enhance electron transfer capacity, the as-prepared electrocatalyst exhibits high catalytic activity with low overpotential of 117 mV and 121 mV to achieve current density of 10 mA cm-2 in acidic and alkaline solutions. Due to the strategy of carbon shells encapsulating, the catalyst presents robust stability for a long time at various applied potential. Furthermore, the design idea of using multiple strategies preparing catalysts may serve some inspiration to fabricate advanced electrocatalysts.