Search

Magnetic agglomeration of CoB nanoparticles in the hydrogen production from the hydrolysis of NaBH4 aqueous solution always degrades their catalytic activity. This work aims at the rational development of robust supported CoB catalyst that is active and stable towards NaBH4 hydrolysis. In this study, PANI nanotubes derived from PS nanofiber templates are firstly synthesized by the polymerization of aniline followed by the template removal. CoB nanoparticles are then decorated into PANI nanotubes via an impregnation and chemical reduction method. It can be found that CoB nanoparticles can be confined into the internal surface of PANI nanotubes which improves the dispersion and anchored stability of CoB nanoparticles. The as-prepared CoB/PANI composite catalyst exhibits a high catalytic performance and recycling stability. The hydrogen production rate as high as 2300 ml. min−1. g − 1 is achieved and the activation energy was calculated to be only 37.75 kJ/mol. Meanwhile, CoB/PANI catalyst displays excellent stability in NaBH4 hydrolysis during five cycles. The experimental results indicated that as-synthesized CoB/PANI composite catalysts are very efficient towards hydrogen production from NaBH4 hydrolysis.

PURPOSE To study effects of bioactive glass with high phosphorus content (10.8% P2O5, 54.2% SiO2, 35% CaO, mol%, named PSC) on mineralization of type I collagen fibrils. METHODS (1) PSC, and PSC combining 0.1 mg/mL, 0.5 mg/mL, or 1.0 mg/mL polyacrylic acid (PAA), were used to induce the mineralization of self-assembled type I collagen fibrils. After 3 and 7 days of mineralization, collagen fibrils were observed by transmission electron microscopy (TEM) and selected area electron diffraction (SAED). (2) PSC suspension was dialyzed in simulated body fluid (SBF), or in SBF containing 0.1 mg/mL, 0.5 mg/mL, or 1.0 mg/mL PAA, to form amorphous calcium phosphate (ACP), then observed by TEM. RESULTS (1) PSC and PSC combining 0.1 mg/mL or 0.5 mg/mL PAA induced mainly extrafibrillar mineralization. PSC combining 1.0 mg/mL PAA induced both extrafibrillar and intrafibrillar mineralization. (2) The ACP induced by PSC or PSC combining 0.1 mg/mL PAA partly formed lattice structure after 24 h. The particle size of the ACP induced by PSC combining 0.5 mg/mL PAA was 100-150 nm, and that induced by PSC combining 1.0 mg/mL PAA was 30-50 nm. CONCLUSION PSC induced mainly extrafibrillar mineralization, and PSC combining an appropriate concentration (1.0 mg/mL) of PAA induced both extrafibrillar and intrafibrillar mineralization.

Agglomeration of CoB catalysts is a severe problem in hydrogen generation from NaBH4 hydrolysis. Herein, highly dispersed carbon nanofiber immobilized CoB catalysts (CoB/CN) were synthesized by a combined prereduction and carbonization method, which is used in hydrogen generation from NaBH4 hydrolysis. Morphological evolution of carbon nanofibers, phase structure and elemental distribution of CoB/CN catalysts are explored by X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). Compared to Co/carbon nanofiber catalysts (Co/CN) without prereduction, CoB/CN catalysts can afford higher CoB dispersity and specific surface area because the migration rate of cobalt species during carbonization is effectively retarded by prereduction. Hence the agglomeration of magnetic CoB nanoparticles can be effectively inhibited. The hydrogen generation experiment shows that CoB/CN catalysts process higher catalytic activity and lower activation energy than Co/CN.

Background Essential oils (EOs) of Lavandula angustifolia, mainly consist of monoterpenoids and sesquiterpenoids, are of great commercial value. The multi-flower spiciform thyrse of lavender not only determines the output of EOs but also reflects an environmental adaption strategy. With the flower development and blossom in turn, the fluctuation of the volatile terpenoids displayed a regular change at each axis. However, the molecular mechanism underlying the regulation of volatile terpenoids during the process of flowering is poorly understood in lavender. Here, we combine metabolite and RNA-Seq analyses of flowers of five developmental stages at first- and second-axis (FFDSFSA) and initial flower bud (FB0) to discover the active terpenoid biosynthesis as well as flowering-related genes. Results A total of 56 mono- and sesquiterpenoids were identified in the EOs of L. angustifolia ‘JX-2’. FB0’ EO consists of 55 compounds and the two highest compounds, β-trans-ocimene (20.57%) and (+)-R-limonene (17.00%), can get rid of 74.71 and 78.41% aphids in Y-tube olfactometer experiments, respectively. With sequential and successive blossoms, temporally regulated volatiles were linked to pollinator attraction in field and olfaction bioassays. In three characteristic compounds of FFDSFSA’ EOs, linalyl acetate (72.73%) and lavandulyl acetate (72.09%) attracted more bees than linalool (45.35%). Many transcripts related to flowering time and volatile terpenoid metabolism expressed differently during the flower development. Similar metabolic and transcriptomic profiles were observed when florets from the two axes were maintained at the same maturity grade. Besides both compounds and differentially expressed genes were rich in FB0, most volatile compounds were significantly correlated with FB0-specific gene module. Most key regulators related to flowering and terpenoid metabolism were interconnected in the subnetwork of FB0-specific module, suggesting the cross-talk between the two biological processes to some degree. Conclusions Characteristic compounds and gene expression profile of FB0 exhibit ecological value in pest control. The precise control of each-axis flowering and regular emissions at transcriptional and metabolic level are important to pollinators attraction for lavender. Our study sheds new light on lavender maximizes its fitness from “gene-volatile terpenoid-insect” three layers. Electronic supplementary material The online version of this article (10.1186/s12870-019-1908-6) contains supplementary material, which is available to authorized users.

This work focused on fabricating mesoporous bioactive glass nanospheres with large pore (LMBGs) by means of a biphase delamination approach and the self-assembly of the reactants took place at the oil-water interface. The morphology and mesostructure of LMBGs were investigated and the results demonstrated that the well-dispersed LMBGs with a radial mesoporous structure and large pore size could be easily tuned by adjusting the reaction temperature using hexadecyl trimethyl ammonium bromide (CTAB) as a template agent and triethanolamine (TEA) as a hydrolysis catalyst. The special structure and outstanding property of LMBGs probably endowed it with a bright prospect in the application of drug delivery systems.

Phytic acid derived bioactive calcium phosphosilicate (PSC) glasses with a high phosphate content were synthesised by using non-toxic phytic acid as a phosphorus precursor. This study aimed to verify the effects of PSC on the odontogenic differentiation and dentin–pulp complex-like tissue regeneration of dental pulp cells (DPCs). Nitrogen adsorption, field-emission scanning electron microscopy, Fourier transform infrared spectroscopy, pH measurement, and inductively coupled plasma optical emission spectroscopy analyses were performed to characterise PSC. Classical 45S5 bioactive glasses (45S5) were used as positive control. Cell proliferation (1, 3, 5, 7 and 9 days), odontogenic-related gene expression levels (3 and 7 days) and mineralisation ability (21 days) of human DPCs (hDPCs) were evaluated with methylthiazol tetrazolium assay, real-time polymerase chain reaction and alizarin red staining after hDPCs from third molars were treated with PSC or 45S5 extractions. Rat molar crowns with pulp tissues covered by PSC or 45S5 were transplanted subcutaneously into nude mice for 2 and 6 weeks to demonstrate their biological effects in vivo. Results revealed that the specific surface area of PSC was larger than that of 45S5. The PSC also induced hydroxycarbonate apatite precipitation earlier than 45S5. pH was slightly increased when the amount and dissolution time of PSCs were increased. By comparison, pH was remarkably increased by 45S5. The amounts of Si and P ions released by PSC (0.1 mg mL−1) were larger than those released by 45S5. Cell proliferation, mRNA expression levels of dentin sialophosphoprotein, dentin matrix protein 1 and osteocalcin and mineralisation of hDPCs were also more strongly promoted by PSC than by 45S5. In vivo, the amount of induced typical dentin-like tissues with odontoblast-like cells generated on the interface between materials and pulp tissues was higher in PSC than in 45S5. Only collagen-like tissues were observed in groups without bioactive glasses. These findings suggested that PSC enhanced the odontogenic differentiation of DPCs and dentin–pulp complex-like tissue regeneration. The PSC might be a potential candidate for vital pulp preservation and regeneration of the dentin–pulp complex.

Introduction This study aimed to evaluate the potential applications of polycaprolactone (PCL)/submicron bioactive glass (smBG) hybrid composites for pulp and dentin tissue regeneration. Methods PCL/smBG hybrid composites were made with novel monodispersive bioactive glass submicrospheres, and pure PCL and bioactive glass samples were used as controls. Surface characteristics were assessed by scanning electron microscopy. Crystalline apatite deposition in vitro was examined after incubation in simulated body fluid. Inductively coupled plasma spectroscopy was used to further analyze the concentration of Si ions released by the scaffolds. Cell adhesion and morphology of human dental pulp cells were observed by immunofluorescence staining. The proliferation and expression of odontogenic-related markers were subsequently investigated using the Cell Counting Kit-8 assay (Beyotime Institute of Biotechnology, Jiangsu, China), Western blotting, and real-time reverse-transcription polymerase chain reaction. Mineralization activity was assessed by alizarin red staining. Results Crystalline apatites were precipitated on the PCL/smBG hybrid and pure bioactive glass surfaces after incubation in vitro , and pure PCL did not exhibit precipitation. Surface deposition on PCL/smBG hybrids presented different topographies and was thicker than on pure bioactive glass scaffolds at a later stage. Human dental pulp cells had a significantly higher proliferation rate on the PCL/smBG hybrid than on the bioactive glass and PCL scaffolds. Furthermore, the integration of smBG into the hybrid scaffold significantly promoted the expression of markers for odontogenic differentiation. More mineralized nodules were generated in the PCL/smBG group than in the other 2 groups. Conclusions PCL/smBG hybrid composites may serve as potential material for pulp repair and dentin regeneration. The physical and chemical properties of the bioactive glass component affect the bioactivity of hybrid composites.

Secondary deuterium isotope effects (IEs) on basicities of isotopologues of trimethylamine have been accurately measured by an NMR titration method applicable to a mixture. Deuteration definitely increases the basicity, by approximately 0.021 in the Delta pK per D. The IE is attributed to the lowering of the CH stretching frequency and zero-point energy by delocalization of the nitrogen lone pair into the C-H antibonding orbital. Because this depends on the dihedral angle between the lone pair and the C-H, a further consequence is a preference for conformations with H antiperiplanar to the lone pair and D gauche. This leads to a predicted nonadditivity of IEs, which is confirmed experimentally. It is found that the decrease in basicity, per deuterium, increases with the number of deuteriums. The nonadditivity of IEs is a violation of the widely assumed Rule of the Geometric Mean.

Secondary deuterium isotope effects (IEs) on acidities have been accurately measured by an NMR titration method applicable to a mixture of isotopologues. Deuteration definitely decreases the acidity of carboxylic acids and phenols, by up to 0.031 in the DeltapK per D. For aliphatic acids, the IEs decrease as the site of deuteration becomes more distant from the OH, as expected, but a surprising result is that IEs in both phenol and benzoic acid do not decrease as the site of deuteration moves from ortho to meta to para. The experimental data are supported by ab initio computations, which, however, substantially overestimate the IEs. The discrepancy does not seem to be due to solvation. The IEs originate in isotope-sensitive vibrations whose frequencies and zero-point energies are lowered upon deprotonation. In the simplest case, formate, the key vibration can be recognized as the C-H stretch, which is weakened by delocalization of the oxygen lone pairs. For the aromatic acids, delocalization cannot account for the near constancy of IEs from ortho, meta, and para deuteriums, but the observed IEs are consistent with calculated vibrational frequencies and electron densities. Moreover, the ability of the frequency analysis to account for the IEs is evidence against an inductive origin.

An efficient kinetic resolution of racemic Betti base with L-(+)-tartaric acid in acetone was developed based on a novel enantioselective N,O-deketalization, by which the enantiopure R- and S-enantiomers of Betti base were obtained as the corresponding N,O-ketal compound and salt with L-(+)-tartaric acid, respectively, in excellent yields with a practically foolproof operation.

A novel and practical preparation of 2-pyridone-containing tricyclic alkaloid derivatives was developed. By regioselective intramolecular N- and C-acylation of 2-(4-aryl-2-pyridon-6-yl)benzoic acid, a pair of structural isomers 2-aryl pyrido[2,1-a]isoindole-4,6-diones and 4-aryl 1-methyl-1H-indeno[1,2-b]-pyridine-2,5-diones, as potential inhibitors of tumor cell proliferation, were prepared respectively.

A novel three-step synthesis of 3-aryl beta-carbolin-1-ones from non-indole starting materials has been developed. The two nitrogen atoms in beta-carbolin-1-one were introduced efficiently by Michael addition of ethyl acetamidocyanoacetate to chalcone. The desired pyridone and indole rings were assembled by an intramolecular ketone-nitrile annulation mediated by aqueous HCl-HOAc and a Cu(I)-catalyzed intramolecular N-arylation of the amide, respectively. The target compounds were found to possess significant activity against tumor cell proliferation.

An improved synthesis of homochiral 1-[α-(1-azacycloalkyl)benzyl]-2-naphthols and 1-[α-(2-arylpiperidyl)benzyl]-2-naphthols has been achieved by employing diastereomerically pure α-benzotriazolyl 1-azacycloalka[2,1-b][1,3]oxazines as homochiral precursors, which were obtained by condensation between nonracemic Betti base and dialdehydes in the presence of benzotriazole.

An extremely convenient method for deprotection of acetals and ketals catalyzed by molecular iodine (10 mol %) in acetone is reported. The protocol achieved the deprotection of acyclic or cyclic O,O-acetals and O,O-ketals in excellent yields within a few minutes under neutral conditions. The double bond, hydroxyl group, and acetate group remained unchanged, and the highly acid-sensitive furyl, tert-butyl ethers, and ketone-oxime stayed intact under these conditions.

Fluorescent α,α′-diamide substituted bi- and terthiophene derivatives were prepared by Stille and Suzuki couplings. Their one-pot deprotection and coupling with 2-thiophene carboxaldehyde led to stable conjugated azomethines. These exhibited electrochromic properties, and they were used to fabricate a working electrochromic device.

Progress in the development of nonviral gene delivery vectors continues to be hampered by low transfection activity and toxicity. Here we proposed to develop a lipid prodrug based on a polyamine analogue bisethylnorspermine (BSP) that can function dually as gene delivery vector and, after intracellular degradation, as active anticancer agent targeting dysregulated polyamine metabolism. We synthesized a prodrug of BSP (LS-BSP) capable of intracellular release of BSP using thiolytically sensitive dithiobenzyl carbamate linker. Biodegradability of LS-BSP contributed to decreased toxicity compared with nondegradable control L-BSP. BSP showed a strong synergistic enhancement of cytotoxic activity of TNF-related apoptosis-inducing ligand (TRAIL) in human breast cancer cells. Decreased enhancement of TRAIL activity was observed for LS-BSP when compared with BSP. LS-BSP formed complexes with plasmid DNA and mediated transfection activity comparable to DOTAP and L-BSP. Our results show that BSP-based vectors are promising candidates for combination drug/gene delivery.

Total syntheses of enantiopure alkaloidal natural products (2S,6R)-dihydropinidine (as hydrochloride) and (2S,6R)-isosolenopsins (as hydrochlorides) were achieved in four steps and in 80−82% total yields by using a synthetic strategy of the formation-cleavage of 1,3-oxazinane. (S)-Betti base was proved to be an excellent chiral auxiliary and a novel Pd/C catalyzed N-debenzylation straightforward to amine hydrochloride was developed in the presence of CH2Cl2.