Electrical tuning of branched flow of light.

Branched flows occur ubiquitously in various wave systems, when the propagating waves encounter weak correlated scattering potentials. Here we report the experimental realization of electrical tuning of the branched flow of light using a nematic liquid crystal (NLC) system. We create the physical realization of the weakly correlated disordered potentials of light via the inhomogeneous orientations of the NLC. We demonstrate that the branched flow of light can be switched on and off as well as tuned continuously through the electro-optical properties of NLC film. We further show that the branched flow can be manipulated by the polarization of the incident light due to the optical anisotropy of the NLC film. The nature of the branched flow of light is revealed via the unconventional intensity statistics and the rapid fidelity decay along the light propagation. Our study unveils an excellent platform for the tuning of the branched flow of light which creates a testbed for fundamental physics and offers a new way for steering light.

Tannin-Derived Hard Carbon for Stable Lithium-Ion Anode.

Graphite anodes are well established for commercial use in lithium-ion battery systems. However, the limited capacity of graphite limits the further development of lithium-ion batteries. Hard carbon obtained from biomass is a highly promising anode material, with the advantage of enriched microcrystalline structure characteristics for better lithium storage. Tannin, a secondary product of metabolism during plant growth, has a rich source on earth. But the mechanism of hard carbon obtained from its derivation in lithium-ion batteries has been little studied. This paper successfully applied the hard carbon obtained from tannin as anode and illustrated the relationship between its structure and lithium storage performance. Meanwhile, to further enhance the performance, graphene oxide is skillfully compounded. The contact with the electrolyte and the charge transfer capability are effectively enhanced, then the capacity of PVP-HC is 255.5 mAh g-1 after 200 cycles at a current density of 400 mA g-1, with a capacity retention rate of 91.25%. The present work lays the foundation and opens up ideas for the application of biomass-derived hard carbon in lithium anodes.

Fusapyrone A, a γ-pyrone derived from a desert Fusarium sp.

In this work, we isolated and characterized fusapyrone A (1), a new γ-pyrone derivative, along with six previously described compounds from the rice fermentation of Fusarium sp. CPCC 401218, a fungus collected from the desert. The structure of 1 was characterized using various spectroscopic analyses, such as MS, IR, 1D, and 2D NMR. The absolute configuration of 1 was determined through the use of 13C NMR chemical shifts, electronic circular dichroism (ECD) and optical rotation (OR) calculations. Compound 1 was found to have weak antiproliferative activity for Hela cells, with an IC50 of 50.6 µM.[Formula: see text].

Ahmpatinin iBu, a new HIV-1 protease inhibitor, from Streptomyces sp. CPCC 202950.

Ahmpatinin iBu (1) and statinin iBu (2), two new linear peptides, a novel pyrrolidine derivative, (-)-(S)-2-[3-(6-methylheptanamido)-2-oxopyrrolidin-1-yl] acetic acid (3), and three known pepstatin derivatives (4-6) along with their corresponding methanolysis artifacts (7-9) were isolated from Streptomyces sp. CPCC 202950. Their structures were elucidated on the basis of extensive spectroscopic data using Marfey's analysis, chiral-phase HPLC, and ECD and OR calculation to determine the absolute configurations. Compound 1 contains an unusual amino acid, 4-amino-3-hydroxy-5-(4-methoxyphenyl)pentanoic acid (Ahmppa), and 3 is the first natural product with a 2-(3-amino-2-oxopyrrolidin-1-yl)acetic acid system. Compounds 1, 2, and 4-9 are HIV-1 protease inhibitors. In particular, ahmpatinin iBu (1) exhibits significant inhibitory activity against HIV-1 protease with an IC50 value of 1.79 nM. A preliminary structure-activity relationship is discussed.

[A new benzamide derivative from rice fermentation of Streptomyces sp. CPCC 202950].

Eight compounds were isolated from the rice fermentation of Streptomyces sp. CPCC 202950 by a combination of various chromatographic techniques including column chromatography over silica, Sephadex LH-20, flash C18, and reversed-phase HPLC. Their structures were identified as 3-[(3'-amino-3'-oxoprop-1'-en-2'-yl)oxy]benzamide (1), m-hydroxybenzamide (2), leptosphaepin (3), 5-methyluracil (4), feruloylamide (5), p-hydroxyphenylacetoamide (6), vanillamide (7), cyclo (L-val-L-ala) (8). Among them, 1 was a new benzamide analogue, and 2 was a new natural product. In the preliminary assays, none of the compounds 1-8 exhibited obvious inhibition of HIV-1 protease activity, and toxic with the Hela, HepG2, and U2OS cells. (IC50 > 10 µmol•L⁻¹).

Highly Active Gold(I)-Silver(I) Oxo Cluster Activating sp³ C-H Bonds of Methyl Ketones under Mild Conditions.

The activation of C(sp(3))-H bonds is challenging, due to their high bond dissociation energy, low proton acidity, and highly nonpolar character. Herein we report a unique gold(I)-silver(I) oxo cluster protected by hemilabile phosphine ligands [OAu3Ag3(PPhpy2)3](BF4)4 (1), which can activate C(sp(3))-H bonds under mild conditions for a broad scope of methyl ketones (RCOCH3, R = methyl, phenyl, 2-methylphenyl, 2-aminophenyl, 2-hydroxylphenyl, 2-pyridyl, 2-thiazolyl, tert-butyl, ethyl, isopropyl). Activation happens via triple deprotonation of the methyl group, leading to formation of heterometallic Au(I)-Ag(I) clusters with formula RCOCAu4Ag4(PPhpy2)4(BF4)5 (PPhpy2 = bis(2-pyridyl)phenylphosphine). Cluster 1 can be generated in situ via the reaction of [OAu3Ag(PPhpy2)3](BF4)2 with 2 equiv of AgBF4. The oxo ion and the metal centers are found to be essential in the cleavage of sp(3) C-H bonds of methyl ketones. Interestingly, cluster 1 selectively activates the C-H bonds in -CH3 rather than the N-H bonds in -NH2 or the O-H bond in -OH which is traditionally thought to be more reactive than C-H bonds. Control experiments with butanone, 3-methylbutanone, and cyclopentanone as substrates show that the auration of the C-H bond of the terminal methyl group is preferred over secondary or tertiary sp(3) C-H bonds; in other words, the C-H bond activation is influenced by steric effect. This work highlights the powerful reactivity of metal clusters toward C-H activation and sheds new light on gold(I)-mediated catalysis.

Mesoporosity changes from cambium to mature tension wood: a new step toward the understanding of maturation stress generation in trees.

In order to progress in the understanding of mechanical stress generation, the mesoporosity of the cell wall and its changes during maturation of poplar (Populus deltoides × P. nigra) tension wood (TW) and opposite wood (OW) were measured by nitrogen adsorption-desorption. Variations in the thickness of the gelatinous layer (G-layer) were also measured to clarify whether the mesoporosity change simultaneously with the deposition of the G-layer in TW. Results show that mesoporous structures of TW and OW were very similar in early development stages before the deposition of G-layers. With the formation of the S2 layer in OW and the G-layer in TW, the mesopore volume decreased steeply before lignification. However, in TW only, the decrease in mesopore volume occurred together with the pore shape change and a progressive increase in pore size. The different patterns observed in TW revealed that pores from G-layers appear with a different shape compared to those of the compound middle lamella, and their size increases during the maturation process until stabilising in mature wood. This observation strongly supports the hypothesis of the swelling of the G-layer matrix during maturation as the origin of maturation stress in poplar tension wood.

Deposition and organisation of cell wall polymers during maturation of poplar tension wood by FTIR microspectroscopy.

To advance our understanding of the formation of tension wood, we investigated the macromolecular arrangement in cell walls by Fourier transform infrared microspectroscopy (FTIR) during maturation of tension wood in poplar (Populus tremula x P. alba, clone INRA 717-1B4). The relation between changes in composition and the deposition of the G-layer in tension wood was analysed. Polarised FTIR measurements indicated that in tension wood, already before G-layer formation, a more ordered structure of carbohydrates at an angle more parallel to the fibre axis exists. This was clearly different from the behaviour of opposite wood. With the formation of the S2 layer in opposite wood and the G-layer in tension wood, the orientation signals from the amorphous carbohydrates like hemicelluloses and pectins were different between opposite wood and tension wood. For tension wood, the orientation for these bands remains the same all along the cell wall maturation process, probably reflecting a continued deposition of xyloglucan or xylan, with an orientation different to that in the S2 wall throughout the whole process. In tension wood, the lignin was more highly oriented in the S2 layer than in opposite wood.

[The modification of apoptosis correlated gene, protein and protein activity in rat hippocampus induced by benzo[a] pyrene sub-chronic exposure].

OBJECTIVE: To observe the effects of subchronic exposure to benzo[a]pyrene (B[a]P) on the mRNA and protein expression levels of apoptosis-related genes (bax, bcl-2, caspase-3, caspase-6, and caspase-9) and the activities of Caspase-3, Caspase-6, and Caspase-9 in the hippocampal neurons of rats and to investigate the neurotoxic mechanism by which B[a]P induces the apoptosis of neurons. METHODS: Fifty-two healthy SD rat were randomly divided into five groups according to preliminary neurobehavioral test results: blank control group, solvent control group, and 1.0, 2.5, and 6.25 mg/kg B[a]P exposure groups; the rats in exposure groups were intraperitoneally injected with B[a]P every other day for 90 days. The Morris water maze was used to test the learning and memory ability of rats; flow cytometry was used to measure the apoptosis ratio of hippocampal neurons; real-time quantitative PCR and Western blot were used to measure the mRNA and protein expression levels of apoptosis-related genes; spectrophotometry was used to measure the activities of their en-coded proteins. RESULTS: Compared with the blank control group, solvent control group, and 1.0 mg/kg B[a]P exposure group, the 2.5 and 6.25 mg/kg B[a]P exposure groups hada significantly longer mean escape latency period (P < 0.05) and a significantly increased number of times of platform crossing (P < 0.05), and the 6.25 mg/kg B[a]P exposure group had significantly lower length and percentage of time spent in the platform quadrant (P < 0.05). The early apoptosis ratio rose as the dose of B[a]P increased (P trend < 0.05); the early apoptosis ratios of 1.0, 2.5, and 6.25 mg/kg B[a]P exposure groups were significantly higher than those of blank control group and solvent control group (P < 0.05). Compared with the blank control group, solvent control group, and 1.0 and 2.5 mg/kg B[a]P exposure groups, the 6.25 mg/kg B[a]P exposure group had significantly increased Bax expression (P < 0.05) and significantly decreased Bcl-2 expression and Bcl-2/Bax ratio (P < 0.05). The 2.5 and 6.25 mg/kg B[a]P exposure groups had significantly higher expression levels of Caspase-3 and Caspase-6 than the blank control group, solvent control group, and 1.0 mg/kg B[a]P exposure group (P < 0.05). The activities of Caspase-3, Caspase-6, and Caspase-9 were significantly higher in the 2.5 and 6.25 mg/kg B[a]P exposure groups than in the blank control group and solvent control group (P < 0.05). There was a positive correlation between the activities of Caspase-3, Caspase-6, and Caspase-9 and early apoptosis ratio of hippocampal neurons in rats (r = 0.793, P = 0.019; r = 0.886, P = 0.006; r = 0.773, P = 0.025). There were no significant differences in the mRNA expression of Bax, Bcl-2, Caspase-3, Caspase-6, and Caspase-9 among these groups (P > 0.05). CONCLUSION: Subchronic exposure to B[a]P can induce apoptosis of hippocampal neurons; its mechanism may be related to the fact that B[a]P can induce upregulated expression of Bax, inhibit expression of Bcl-2, lead to decrease in Bcl-2/Bax ratio, induce upregulated expression of Caspase-3 and Caspase-6, and cause increase in the activities of Caspase-3, Caspase-6, and Caspase-9.

[Effects of subchronic benzo[a]pyrene exposure on hippocampal cholinergic system in rats].

OBJECTIVE: To observe the effects of subchronic benzo[a]pyrene (B[a]P) exposure on the neurobehavior and hippocampal acetylcholine (Ach) level, acetylcholinesterase (AChE) activity, and mRNA and protein expression of nicotinic acetylcholine receptor α7 subtype (nAChR α7) in rats, and to investigate the neurotoxic mechanism of B[a]P. METHODS: Sixty healthy male SD rats were randomly divided into blank control group, solvent control group, and B [a]P exposure groups. Each rat in the exposure groups was intraperitoneally injected with B[a]P at 1.0, 2.5, or 6.25 mg/kg once every other day for 90 days. The learning and memory ability of the rats was examined by Morris water maze test and step-down test; the hippocampal Ach level was measured by alkaline hydroxylamine method; the AChE activity was measured by DNTB method; the mRNA and protein expression levels of hippocampal nAChR α7 were measured by quantitative PCR and Western blot. RESULTS: The 2.5 and 6.25 mg/kg B[a]P exposure groups showed significantly lower learning and memory abilities than the blank control group and solvent control group (P < 0.05); also, the two groups had significantly lower hippocampal Ach levels than the blank control group, solvent control group, and 1.0 mg/kg B[a]P exposure group (P < 0.05). The 6.25 mg/kg B[a]P exposure group showed significantly lower hippocampal AChE activity than the blank control group, solvent control group, and 1.0 mg/kg B[a]P exposure group (P < 0.05). There were no significant differences in the mRNA and protein expression levels of nAChR α7 among all groups (P > 0.05). The hippocampal Ach level was negatively correlated with the mean escape latency period and total distance travelled (r = -0.567, P < 0.01; r = -0.503, P < 0.01) but positively correlated with the time in platform quadrant (r = 0.800, P < 0.01). CONCLUSION: Subchronic B[a]P exposure may impair the learning and memory ability in rats, which is related to the downregulation of hippocampal Ach level.

[Effect of Ganoderma lucidum polysaccharides on oxidative stress of hyperlipidemic fatty liver in rats].

OBJECTIVE: To study the effect of Ganoderma lucidum polysaccharides on oxidative stress of hyperlipidemic fatty liver in rats. METHOD: Seventy-two SD rats were randomly divided into six groups, namely the normal control group (NG), the model group (MG), the G. lucidum polysaccharides groups of low, middle and high dose (GLPs-LG, GLPs-MG, GLPs-HG) and the Simvastatin group (SV). The rats were fed with high fat diet to establish the model of hyperlipidemic fatty liver in rats. After administration for 12 weeks, rats in each group were tested with the following indexes: total cholesterol (TC), triglyceride (TG), high density lipoprotein-cholesterol (HDL-C) and low density lipoprotein-cholesterol (LDL-C), malondialdehyde (MDA), superoxide dismutase (SOD), glutathione peroxidase (GSH-Px) and total antioxidant capacity (T-AOC) in serum as well as the contents of SOD, MDA, GSH-Px and T-AOC in hepatic tissues. Histopathological changes of hepatic tissues were observed under light glass. RESULTS: The contents of TC, TG and LDL-C were significantly increased in the model group (P < 0.01). Compared with the model group, both the GLPs-M group and the GLPs-H group showed significant decreases in TC, TG and LDL-C (P < 0.05 or P < 0.01), while the GLPs-H group showed a notable increase in HDL-C (P < 0.05). Compared with the model group, both the GLPs-M group and the GLPs-H group showed significant decreases in MDA (P < 0.05 or P < 0.01) and notable increases in SOD, GSH-Px, T-AOC (P < 0.05 or P < 0.01). The GLPs-M group and the GLPs-H group proved a remarkable alleviation in fatty degeneration of hepatic cells. CONCLUSION: G. lucidum polysaccharides can significantly reduce the blood fat level of hyperlipidemic fatty liver in rats and effectively inhibit oxidant stress, showing the effect on preventing and treating hyperlipidemic fatty liver in rats to some extent.

Mesoporosity as a new parameter for understanding tension stress generation in trees.

The mechanism for tree orientation in angiosperms is based on the production of high tensile stress on the upper side of the inclined axis. In many species, the stress level is strongly related to the presence of a peculiar layer, called the G-layer, in the fibre cell wall. The structure of the G-layer has recently been described as a hydrogel thanks to N(2) adsorption-desorption isotherms of supercritically dried samples showing a high mesoporosity (pores size from 2-50 nm). This led us to revisit the concept of the G-layer that had been, until now, only described from anatomical observation. Adsorption isotherms of both normal wood and tension wood have been measured on six tropical species. Measurements show that mesoporosity is high in tension wood with a typical thick G-layer while it is much less with a thinner G-layer, sometimes no more than normal wood. The mesoporosity of tension wood species without a G-layer is as low as in normal wood. Not depending on the amount of pores, the pore size distribution is always centred around 6-12 nm. These results suggest that, among species producing fibres with a G-layer, large structural differences of the G-layer exist between species.