Preparation of metal-free BP/CN photocatalyst with enhanced ability for photocatalytic tetracycline degradation.

The successful application of photocatalysis in practical water treatment opreations relies greatly on the development of highly efficient, stable and low-cost photocatalysts. The low-cost metal-free photocatalyst made up of black phosphorus (BP) and graphitic carbon nitride (CN) was successfully constructed and firstly used for the photocatalytic treatment of antibiotic contaminants in this work. Compared with bare CN, the BP/CN photocatalyst exhibited the enhanced photocatalytic performance for tetracycline hydrochloride (HTC) degradation, that 99% of HTC was removed by 6BP/CN (doping amount of BP was 6%) within 30 min under the simulated visible-light irradiation. The efficiency was even comparable to those of some high-efficiency photocatalysts recently-reported such as Fe0@POCN, CuInS2/Bi2MoO6 and Cu2O@HKUST-1. Under natural sunlight illumination, the determined apparent rate constant for degradation of HTC by BP/CN was 2.7 times as that by P25 TiO2. The experimental results indicated that loading BP on CN could enhance the separation of charge carriers and promote the ability of light absorption for visible-light, thus leading to a greater catalytic activity. Meanwhile, the influences of different operating variables (pH, water, ion and HTC concentration) on HTC degradation were studied in detail. Furthermore, the degradation pathway of HTC was also proposed. In addition, the photocatalytic activity of the BP/CN for production of hydrogen peroxide (H2O2) was also studied, which could reach up to 501.04 µmol g-1h-1. It is anticipated that BP/CN photocatalyst could be used for practical water treatment.

Development of a metal-free black phosphorus/graphitic carbon nitride heterostructure for visible-light-driven degradation of indomethacin.

The development of affordable and efficient technologies for the removal of pharmaceuticals and personal care products (PPCPs) from water has recently been the subject of extensive attention. In this study, a black phosphorus/graphitic carbon nitride (BP-g-C3N4) heterostructure is fabricated as an extremely active metal-free photocatalyst via a newly-developed exfoliation strategy. The BP-g-C3N4 shows an 11 times better decomposition rate of a representative PPCPs-type pollutant, indomethacin (IDM), compared to the widely-used P25 TiO2 under real-sunlight illumination. Also, its visible-light activity is even better than that of the best photocatalysts previously developed, but only consumes 1/10-1/4 of the catalyst. The results show that BP performs a cocatalyst-like behavior to catalyze the generation of reactive oxygen species, thus speeding up the decomposition of IDM. In addition, the BP-g-C3N4 photocatalyst also exhibits excellent IDM removal efficiency in authentic water matrices (tap water, surface water, and secondarily treated sewage effluent). Large-scale application demonstration under natural sunlight further reveals the practicality of BP-g-C3N4 for real-world water treatment operations. Our work will open up new possibilities in the development of purely metal-free photocatalysts for "green" environmental remediation applications.

Synthesis of graphene/black phosphorus hybrid with highly stable P-C bond towards the enhancement of photocatalytic activity.

Black phosphorus (BP), a superior two-dimensional (2D) semiconductor, has attracted much attention due to its unique properties. The graphene (GR)-BP hybrid was synthesized through one pot chemical vapor transport (CVT) approach. The characterization results indicated that P atom was successfully incorporated into GR by the formation of P-C bond. Remarkably, the newly-synthesized GR-BP represented high photocatalytic activity towards 2-chlorophenol (2-CP) degradation, due to the high efficiency of charge separation and transformation caused by the direct band gap of BP and carrier mobility of GR. The removal efficiency for 2-CP reached up to 87.08% within visible light irradiation for 180 min (λ > 420 nm). The degradation rate of GR-BP hybrid for 2-CP was approximately 7.29-fold than that of BP within 30 min. In addition, the little increasing of the peak for P-O bond in GR-BP hybrid was observed after being exposed in air for 15 days, meant that the stability of BP was significantly enhanced. It was caused by the decreasing of the oxidation sites in BP due to the formation of P-C bond in hybrid. In brief, our synthetic method for GR-BP not only provides a novel route for the improvement of the stability of BP, but also constitutes an insight into the promising practical application of BP in the photocatalysis field.

Caesalpinone A, a new type of gorgonane sesquiterpenoid containing an unprecedented 1,15-bridge, from the pods of Caesalpinia spinosa Kuntze.

Caesalpinone A (1), a new type of gorgonane sesquiterpenoid containing an unprecedented 1,15-bridge, along with ten known sesquiterpenoids (2-11) were isolated from the pods of Caesalpinia spinosa Kuntze (Tara). The structure of caesalpinone A was elucidated based on its 1D and 2D NMR spectra. The absolute configuration of 1 was assigned by the comparison of the experimental and calculated electronic circular dichroism spectra. Compound 1 was evaluated for the inhibitory activities against five human tumor cell lines. The sesquiterpenoids of isodaucane skeleton and caryolane skeleton were isolated from Caesalpinia genus for the first time. Compounds 5-9 were firstly reported from Tara.

Six new cassane diterpenes from the twigs and leaves of Tara (Caesalpinia spinosa Kuntze).

Six new cassane diterpenes, isoneocaesalpin H (1), caespinosin A (2), caespinosin B (3), a cassane diterpene with unique 6/6/7 carbon rings, and caespinosins C-E (4-6) were isolated from the twigs and leaves of Tara (Caesalpinia spinosa Kuntze). The absolute configuration of isoneocaesalpin H (1) was determined by single-crystal X-ray crystallographic analysis. Compound 3 represents a class of rare natural cassane diterpene bearing unique 6/6/7 carbon rings. Their structures were identified by 1D and 2D NMR spectral data. Cassane diterpenes were firstly reported from Tara. Compounds 1-5 were evaluated for their cytotoxicity on HL-60, SMMC-7721, A-549, MCF-7 and SW-480 human cancer cell lines, but they were inactive.

A new natural naphtho[1,2-b]furan from the leaves of Cassia fistula.

A new naphtho[1,2-b]furan, 2,9-dihydroxy-7-methoxy-4-methylnaphtha[1,2-b]furan-3(2H)-one (1), along with 10 known compounds vanillic acid (2), naringenin (3), glyceryl-1-tetracosanoate (4), moracin J (5), 1,3,8-trihydroxyanthraquinone (6), esculetin (7), mauritianin (8), kaempferol 3-neohesperidoside (9), ß-sitosterol (10), and ß-daucosterol (11), was isolated from the leaves of Cassia fistula. The structure of the new compound was determined by NMR and X-ray analysis. Compounds 1, 3, 5-9 were isolated from this plant for the first time. The naphtha[1,2-b]furan was firstly isolated from the natural resources.

Effect of different levels of short-term feed intake on folliculogenesis and follicular fluid and plasma concentrations of lactate dehydrogenase, glucose, and hormones in Hu sheep during the luteal phase.

This study investigated the effects of short-term food restriction or supplementation on folliculogenesis and plasma and intrafollicular metabolite and hormone concentrations. Ewes were randomly assigned to three groups: the control group received a maintenance diet (M) while the supplemented group and restricted group received 1.5×M and 0.5×M respectively on days 6-12 of their estrous cycle. Estrus was synchronized by intravaginal progestogen sponges for 12 days. On days 7-12, blood samples were taken. After slaughter, the ovarian follicles were classified and the follicular fluid was collected. Compared with restriction, supplementation shortened the estrous cycle length, decreased the number of follicles 2.5-3.5 mm and follicular fluid estradiol (E2) concentration, increased the number of follicles>3.5 mm and plasma glucose, insulin and glucagon concentrations, and augmented the volume of follicles>2.5 mm. Restricted ewes had higher intrafollicular insulin concentration, but it was similar to that of supplemented ewes. Compared with follicles≤2.5 mm, the intrafollicular glucose and E2 concentrations were increased and the testosterone, insulin, and glucagon concentrations and lactate dehydrogenase (LDH) activity were decreased in follicles>2.5 mm. Only in restricted ewes were intrafollicular LDH and testosterone concentrations in follicles≤2.5 mm not different from those in follicles≤2.5 mm. In conclusion, the mechanism by which short-term dietary restriction inhibits folliculogenesis may involve responses to intrafollicular increased E2, testosterone, and LDH levels in late-stage follicles. This may not be due to the variation of intrafollicular insulin level but rather due to decreased circulating levels of glucose, insulin, and glucagon.