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An iron-catalysed C-H functionalisation of simple monosubstituted allenes for the synthesis of 1-tetrahydroisoquinolinyl 1,1-disubstituted allenes is reported. This transformation represents the first example of a direct conversion of allenic C-H bonds to C-C bonds through cross dehydrogenative coupling. The optimized protocol features broad scope and employs mild, functional group tolerant conditions.

In spite of their rich stoichiometric chemistry, cyclopentadienyliron(II) dicarbonyl complexes are rarely used as catalysts in organic synthesis. Inspired by precedents in the chemistry of cationic olefin complexes and neutral allylmetal species, our group has developed a coupling of alkynes or alkenes with aldehydes and other carbonyl electrophiles to give homopropargylic and homoallylic alcohols, respectively, by using a substituted cyclopentadienyliron(II) dicarbonyl complex as the catalyst. In this article, we first contextualize this development within the conceptual background of C–H functionalization chemistry and relative to key stoichiometric precedents. We then give an account of our group’s discovery and development of the catalytic α-functionalization of alkenes and alkynes with electrophilic reagents.IntroductionPreliminary Stoichiometric WorkHydroxyalkylation Development and ScopeConclusions and Future Directions

Background: Brucea javanica oil emulsion (BJOE) is a traditional Chinese medicine with recognized antitumor effects in various cancers, but the effects and mechanisms of action of BJOE against cervical cancer need to be further studied. Herein, we investigated the effects of BJOE on the human papillomavirus (HPV)16-expressing human cervical cancer line SiHa and explored the possible underlying mechanisms. Methods: Cell viability and apoptosis of SiHa cells treated with BJOE were assessed by the MTT [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide] and annexin V-fluorescein isothiocyanate (annexin V-FITC)/propidium iodide (PI) staining assays, respectively. Quantitative reverse transcription- polymerase chain reaction and Western blot analyses were performed to assess the expression levels of the E6 oncogene and key signaling molecules involved in apoptosis. A subcutaneous xenograft nude mouse model bearing SiHa cells was established and treated with BJOE through intraperitoneal injection. Tumor growth was monitored, and immunohistochemical analysis was performed. Results: BJOE exhibited substantial cytotoxic effects in SiHa cells and significantly suppressed tumor growth in SiHa cell xenografts. BJOE inhibited E6 expression and induced apoptosis in vitro in a dose- dependent manner. BJOE-induced apoptosis was characterized by activation of caspase-3 and cleavage of poly(ADP-ribose) polymerase (PARP). Moreover, BJOE induced phosphorylation of extracellular-signal regulated kinase (ERK) and inhibited the expression of nuclear factor-kappa B (NF-κB). Conclusions: BJOE exerts a strong tumor-suppressive effect in SiHa cells in vitro and in vivo , likely caused by E6 inhibition and apoptosis induction achieved through the ERK/mitogen-activated protein kinase (MAPK) and NF-κB signaling pathways, supporting potential use of BJOE in cervical cancer treatment.

Six flavonoid glycosides ( 1 – 3 , 6 – 8 ), one lignan ( 4 ), and one galloyl glycoside ( 5 ) were isolated based on the phytochemical study for the MeOH extract of Polygonum aviculare L. herb. The eight isolated compounds' structures were determined by comparing their physicochemical and spectral data with published ones. Compounds 5 and 6 were first isolated from this plant, and all the compounds were evaluated for DNA topoisomerase inhibitory activities and cytotoxicities. Among the purified compounds, 5 showed stronger inhibitory activity against topoisomerase I with an IC 50 value of 12.0 μM, while the value of positive control camptothecin (CPT) was 17.0 μM. For compounds 1 , 3 , and 5 – 8 , the value ranged from 0.054 to 17.0 µM, suggesting more potent inhibitory activity against topoisomerase II, and that of etoposide (VP-16) was 28.0 µM. Particularly, compounds 6 and 8 (IC 50 = 0.054 and 0.077 µM, respectively) inhibited Topo II about 500 times stronger than VP-16, making them safer agents of DNA topoisomerase. Furthermore, all compounds demonstrated no cytotoxic activity against four cancer cell lines. This study is the first to report the inhibition of DNA topoisomerases of compounds from P. aviculare , suggesting that these compounds may be potential candidates for treating cancer.

An iron-catalyzed C-H functionalization of simple monosubstituted allenes is reported. An efficient protocol for this process was made possible by the use of a newly developed electron-rich and sterically hindered cationic cyclopentadienyliron dicarbonyl complex as the catalyst and N-sulfonyl hemiaminal ether reagents as precursors to iminium ion electrophiles. Under optimized conditions, the use of a mild, functional-group-tolerant base enabled the conversion of a range of monoalkyl allenes to their allenylic sulfonamido 1,1-disubstituted derivatives, a previously unreported and contrasteric regiochemical outcome for the C-H functionalization of electronically unbiased and directing-group-free allenes.

Isolation and characterization of a bacteriocin from Brevibacillus laterosporus DS-3 and its ability in producing antibacterial activity were examined in this study. We isolated 48 bacterial strains from different native ecological niches. Sources included lake water, soil, air, and food. Among the isolates from the soil sample, morphological and biochemical tests identified Brev. laterosporus DS-3, which showed great potential for bacteriocin production. It was purified by ammonium sulfate precipitation, then applied in a Sephadex G-15 gel filtration column connected to a purification of AKTA Pure (USA) and reverse phase chromatography. MALDI-TOF mass spectrometry indicated that bacteriocin DS-3 has a low molecular weight of 1592.579 Da. LNTLETEEWFFK was identified as the sequence by mass spectrometry analysis in tandem liquid chromatography and MASCOT research. This bacteriocin inhibited Gram-positive and Gram-negative bacteria and was effective against Methicillin-resistant Staphylococcus aureus (MRSA). Brev. laterosporus DS-3 present in here is thermostable and tolerant to extreme pH. However, inactivation of its antibacterial activity was observed when treated with papain and trypsin but not pepsin, proteinase K, and catalase.

Background: Frequent overdose of paracetamol (APAP) has become the major cause of acute liver injury. The present study was designed to evaluate the potential protective effects of ginsenoside Rk1 on APAP-induced hepatotoxicity and investigate the underlying mechanisms for the first time. Methods: Mice were treated with Rk1 (10 mg/kg or 20 mg/kg) by oral gavage once per d for 7 d. On the 7th d, all mice treated with 250 mg/kg APAP exhibited severe liver injury after 24 h, and hepatotoxicity was assessed. Results: Our results showed that pretreatment with Rk1 significantly decreased the levels of serum alanine aminotransferase, aspartate aminotransferase, tumor necrosis factor, and interleukin-1β compared with the APAP group. Meanwhile, hepatic antioxidants, including superoxide dismutase and glutathione, were elevated compared with the APAP group. In contrast, a significant decrease in levels of the lipid peroxidation product malondialdehyde was observed in the ginsenoside Rk1-treated group compared with the APAP group. These effects were associated with a significant increase of cytochrome P450 E1 and 4-hydroxynonenal levels in liver tissues. Moreover, ginsenoside Rk1 supplementation suppressed activation of apoptotic pathways by increasing Bcl-2 and decreasing Bax protein expression levels, which was shown using western blotting analysis. Histopathological observation also revealed that ginsenoside Rk1 pretreatment significantly reversed APAP-induced necrosis and inflammatory infiltration in liver tissues. Biological indicators of nitrative stress, such as 3-nitrotyrosine, were also inhibited after pretreatment with Rk1 compared with the APAP group. Conclusion: The results clearly suggest that the underlying molecular mechanisms in the hepatoprotection of ginsenoside Rk1 in APAP-induced hepatotoxicity may be due to its antioxidation, antiapoptosis, anti-inflammation, and antinitrative effects. Keywords: anti-inflammation, anti-apoptosis, APAP-induced hepatotoxicity, ginsenoside Rk1, oxidative stress

The deprotonation of propargylic C–H bonds for subsequent functionalization typically requires stoichiometric metal alkyl or amide reagents. In addition to the undesirable generation of stoichiometric metallic waste, these conditions limit the functional group compatibility and versatility of this functionalization strategy and often result in regioisomeric mixtures. In this article, we report the use of dicarbonyl cyclopentadienyliron(ii) complexes for the generation of propargylic anion equivalents toward the direct electrophilic functionalization of propargylic C–H bonds under mild, catalytic conditions. This technology was applied to the direct conversion of C–H bonds to C–C bonds for the synthesis of several functionalized scaffolds through a one-pot cross dehydrogenative coupling reaction with tetrahydroisoquinoline and related privileged heterocyclic scaffolds. A series of NMR studies and deuterium-labelling experiments indicated that the deprotonation of the propargylic C–H bond was the rate-determining step when a Cp*Fe(CO)2-based catalyst system was employed., [Cp*Fe(CO)2]+ facilitates the α-deprotonation of unsaturated C–C bond for propargylic and allylic C–H functionalization. Mechanistic studies reveal insights into the superior performance of the electron-rich and hindered ligand on iron.

Vinyl fluorides play an important role in drug development as bioisosteres for peptide bonds and are found in a range of bioactive molecules. The discovery of safe, general and practical procedures to prepare vinyl fluorides from readily available precursors remains a synthetic challenge. The metal-free hydrofluorination of alkynes constitutes an attractive though elusive strategy for their preparation. Here we introduce an inexpensive and easily-handled reagent that enabled the development of simple and scalable protocols for the regioselective hydrofluorination of alkynes to access both the E and Z isomers of vinyl fluorides. These conditions were suitable for a diverse collection of alkynes, including several highly-functionalized pharmaceutical derivatives. Computational and experimental mechanistic studies support C–F bond formation through vinyl cation intermediates, with the (E)- and (Z)-hydrofluorination products forming under kinetic and thermodynamic control, respectively.

Cobalt (Co) is an essential component of several enzymes and coenzymes in living organisms. Excess Co is highly toxic to plants. The knowledge of molecular response mechanisms to cobalt stress in plants is still limited, especially in woody plants. The responses of weeping willow (Salix babylonica) seedlings to Co stress were studied using morphological and physiochemical measurements and RNA-seq analysis. The physiological and biochemical indexes such as growth rate, the content of chlorophyll and soluble sugar, photosynthesis and peroxidase activity were all changed in willow seedlings under Co stress. The metal ion concentrations in willow including Cu, Zn and Mg were disturbed due to excess Co. Of 2002 differentially expressed genes (DEGs), 1165 were root-specific DEGs and 837 were stem and leaf-specific DEGs. Further analysis of DEGs showed there were multiple complex cascades in the response network at the transcriptome level under Co stress. Detailed elucidation of responses to oxidative stress, phytohormone signaling-related genes and transcription factors (TFs), and detoxification of excess cellular Co ion indicated the various defense mechanisms in plants respond to cobalt stress. Our findings provide new and comprehensive insights into the plant tolerance to excess Co stress.

A series of CeO2 nanocrystals with different sizes have been synthesized with DNA as the template by a hydrothermal synthesis method. The peroxidase-like activity of the CeO2 nanocrystals was found to be strongly enhanced by DNA doping.

A highly efficient strategy for remote reductive cross-electrophile coupling has been developed through the ligand-controlled nickel migration/arylation. This general protocol allows the use of abundant and bench-stable alkyl bromides and aryl bromides for the synthesis of a wide range of structurally diverse 1,1-diarylalkanes in excellent yields and high regioselectivities under mild conditions. We also demonstrated that alkyl bromide could be replaced by the proposed olefin intermediate while using n-propyl bromide/Mn0 as a potential hydride source.

Eugenol, the major active essential oil component of clove, was reported to possess QS (quorum sensing) inhibitory activity. A previous study found that eugenol could bind to quorum sensing receptors of Pseudomonas aeruginosa and down-regulate the expression of Streptococcus mutans virulence genes at sub-MIC (minimum inhibitory concentration) without affecting the bacterial growth. However, the alterations of QS signal molecules at transcription levels was not well understood. To better understand interactions of Klebsiella pneumoniae in response to eugenol and explore molecular regulations, transcriptome sequencing was performed. A total of 5779 differentially expressed genes (DEGs) enriched in a variety of biological processes and pathways were identified. The transcriptional data was validated by qPCR and the results showed that the expression profiles of 4 major genes involved in autoinducers-2 (AI-2) synthesis, including luxS, pfs, and lsrK were consistent with transcriptome analysis except for lsrR, a transcriptional repressor gene of lsr operon, which may repress the expression of following genes responsible for AI-2 signal transmission in vivo. In vitro AI-2 synthesis assay also revealed that eugenol could inhibit AI-2 generation. The results of our study offer insights into the mechanisms of QS inhibitory activity and K. pneumoniae AI-2 alterations after eugenol treatment.

The enantioselective, intermolecular hydroallylation of vinylarenes employing allylic phosphate electrophiles has been achieved through a copper hydride catalyzed process. The protocol described herein can be applied to a diverse set of vinylarene substrates and allows for the installation of the parent allyl group as well as a range of 2-substituted allylic fragments.

Background Bacterial infections have become more challenging to treat due to the emergence of multidrug-resistant pathogenic bacteria. Combined antibiotics prove to be a relatively effective method to control such resistant strains. This study aim to investigate synergistic activity of eugenol combined with colistin against a collection of clinical isolated Escherichia coli (E.coli) strains, and to evaluate potential interaction. Methods Antimicrobial susceptibility, minimum inhibitory concentration (MIC) and fractional inhibitory concentration index (FICI) of the bacteria were determined by disk diffusion assay, broth microdilution method and checkerboard assay, respectively. The mcr-1 mRNA expression was measured by Real-time PCR. To predict possible interactions between eugenol and MCR-1, molecular docking assay was taken. Results For total fourteen strains including eight colistin-resistant strains, eugenol was determined with MIC values of 4 to 8 μg/mL. Checkerboard dilution test suggested that eugenol exhibited synergistic activity when combined with colistin (FICI ranging from 0.375 to 0.625). Comparison analysis of Real-time PCR showed that synergy could significantly down-regulate expression of mcr-1 gene. A metal ion coordination bond with catalytic zinc atom and a hydrogen bond with crucial amino acid residue Ser284 of MCR-1 were observed after molecular docking, indicating antibacterial activity and direct molecular interactions of eugenol with MCR-1 protein. Conclusions Our results demonstrated that eugenol exhibited synergistic effect with colistin and enhanced its antimicrobial activity. This might further contribute to the antibacterial actions against colistin-resistant E.coli strains. Graphical abstract Synergistic effect of eugenol with colistin against colistin-resistant Escherichia coli isolates.

Over the past few years, CuH-catalyzed hydroamination has been discovered and developed as a robust and conceptually novel approach for the synthesis of enantioenriched secondary and tertiary amines. The success in this area of research was made possible through the large body of precedent in copper(I) hydride catalysis and the well-explored use of hydroxylamine esters as electrophilic amine sources in related copper-catalyzed processes. This Minireview details the background, advances, and mechanistic investigations in CuH-catalyzed hydroamination., National Institutes of Health (U.S.) (GM58160), National Institutes of Health (U.S.) (Postdoctoral Fellowship GM113311), National Institutes of Health (U.S.) (Postdoctoral Fellowship GM112218)

Bismuth layer-structured ferroelectric (BLSF) compound strontium bismuth titanate (SrBi 4 Ti 4 O 15 , SBT) with cerium modifications have been synthesized using conventional solid-state processing. X-ray powder diffraction (XRPD) analyses reveal that the cerium-modified SBT ceramics have a pure four-layer Aurivillius-type structure. The dielectric, ferroelectric, and piezoelectric properties of the cerium-modified SBT ceramics are investigated in detail. The results indicate that the cerium modifications into SBT increase the densities, decrease the sintering temperature, lower the dielectric loss tan δ , and reduce the coercive filed E c . The piezoelectric measurements show that cerium is very effective in promoting the piezoelectric properties of SBT ceramics. The SBT ceramics modified with 4 mol% CeO 2 (SBT-4Ce) exhibit the optimized piezoelectric properties, with a piezoelectric constant d 33 of 27 pC/N, which is the highest value among the modified SBT-based piezoelectric ceramics ever reported. The temperature-dependent electrical impedance and electromechanical coupling coefficients ( k p and k t ) reveal that the electromechanical coupling characteristics have a significant deterioration at ~400 °C because of the high conductivity at high temperature. But the temperature-dependent frequency constants ( N p and N t ) and thermal annealing analyses indicate the cerium-modified SBT ceramics have good thermal stabilities of piezoelectric properties up to 450 °C. These results demonstrate that the cerium-modified SBT ceramics are promising materials for high temperature piezoelectric sensors applications.

Bismuth layer-structured ferroelectric (BLSF) calcium bismuth titanate (CaBi 4 Ti 4 O 15 , CBT) piezoelectric ceramics with 0.0–1.0 wt.% cobalt oxide (Co 2 O 3 ) have been prepared via a conventional solid-state reaction method. Microstructural morphology and electrical properties of cobalt oxide-modified CBT ceramics were investigated in detail. X-ray powder diffraction (XRPD) analysis revealed that the cobalt oxide-modified CBT ceramics have a pure four-layer Aurivillius-type structure. The piezoelectric properties of CBT ceramics were significantly enhanced by cobalt oxide modifications. The piezoelectric coefficient d 33 and Curie temperature T c of 0.2 wt. % cobalt oxide-modified CBT ceramics (CBT-Co4) are 14 pC/N and 782 °C, respectively. The DC resistivity and thermal depoling behavior at elevated temperature indicated that the CBT-Co4 ceramics exhibit good thermal stability, demonstrating that the CBT-Co4 ceramics are potential materials for high temperature piezoelectric applications.

Choline chloride (ChCl) was demonstrated to efficiently separate phenols from model oils by forming deep eutectic solvents (DESs). The DES way is a non-aqueous process that avoids the use of mineral alkalis and acids, and prevents the production of wastewater containing phenol. However, real oils, such as coal tar oil and liquefaction oil, consist of a small amount of water, and ChCl is a strong hygroscopic compound, which may influence the removal of phenol in real oil. In this work, the effect of water in mixtures of phenol and toluene (defined as model oils) on the separation of phenol by forming DES with ChCl was studied. The results indicated that water could interact with ChCl to form DES and the interaction between water and ChCl was stronger than that between phenol and ChCl. In the presence of water in model oils, the amount of ChCl should be increased to get the same phenol removal as that without water. Moreover, with water in model oils, the influence of temperature on the phenol removal was more negative. After the reuse of ChCl for four cycles with the presence of water, ChCl accumulated about 23% water and the removal efficiency of phenol decreased from 92% to 87%. To reduce the effect of water on phenol separation, an air drying method could be used to remove water in regenerated ChCl.

The Aurivillius-type bismuth layer-structured ferroelectrics (BLSFs) sodium lanthanum bismuth titanate (Na0.5La0.5Bi4Ti4O15, NLBT) polycrystalline ceramics with 0.0–0.4 wt% MnO2 were synthesized using conventional solid-state processing. Phase analyses were performed by X-ray powder diffraction (XRPD), and the microstructural morphology was assessed by scanning electron microscopy (SEM). The dielectric and piezoelectric properties of the manganese-modified NLBT ceramics were investigated in detail. The results show that manganese is very effective in promoting the piezoelectric activities of NLBT ceramics, and the reasons for piezoelectric activities enhancement by manganese modification are explained. The NLBT ceramics modified with 0.2 wt% MnO2 (NLBT-Mn2) possess good piezoelectric properties, with a piezoelectric coefficient d33 of 28 pC/N. This value is the highest value among the modified NLBT-based piezoelectric ceramics examined. The temperature-dependent dielectric spectra show that the Curie temperature Tc of the manganese-modified NLBT ceramics is slightly higher than that of the pure NLBT ceramics. Thermal annealing analysis revealed that the manganese-modified NLBT ceramics possess good thermal stabilities up to 500 °C. These results demonstrate that the manganese-modified NLBT ceramics are promising materials for high temperature piezoelectric applications.

Chiral-anion phase-transfer catalysis (PTC) has been applied towards the enantioselective fluorocyclization reactions of 1,3-dienes. The method affords unprecedented fluorinated benz[f]isoquinoline and octahydroisoquinoline products in high yields and up to 96 % ee. New fluorinated amine reagents outperformed Selectfluor in the desired transformation.

A surface-initiated immortal alternating polymerization of CO2 and epoxides was presented on the solid materials. By means of rapid and reversible chain transfer, surface-initiated immortal CO2–propylene oxide copolymerization was carried out on the surface of oxidized carbon nanotubes at room temperature. The content and thickness of the functional moieties could be facilely controlled by adjusting the feed ratio of the catalysts to propylene oxide. The modification featured was with a high grafting weight fraction above 90%. The functionalized carbon nanotubes were characterized with FTIR, 1H NMR, 13C NMR, SEM, TEM and TGA. Moreover, the flexible conductive films can be easily fabricated according to the their high dispersion in organic solution. Functionalized multiwalled carbon nanotubes were incorporated into a polycarbonate matrix to improve the mechanical properties.

The enantioselective, intermolecular hydroallylation of vinylarenes employing allylic phosphate electrophiles has been achieved through a copper hydride catalyzed process. The protocol described herein can be applied to a diverse set of vinylarene substrates and allows for the installation of the parent allyl group as well as a range of 2-substituted allylic fragments.

In the current study, we investigated nitrite-dependent anaerobic methane oxidation (N-DAMO) as a potential methane sink in the Hangzhou Bay and the adjacent Zhoushan sea area. The potential activity of the N-DAMO process was primarily observed in Hangzhou Bay by means of (13)C-labeling experiments, whereas very low or no potential N-DAMO activity could be detected in the Zhoushan sea area. The measured potential N-DAMO rates ranged from 0.2 to 1.3 nmol (13)CO2 g(-1) (dry sediment) day(-1), and the N-DAMO potentially contributed 2.0-9.4 % to the total microbial methane oxidation in the examined sediments. This indicated that the N-DAMO process may be an alternative pathway in the coastal methane cycle. Phylogenetic analyses confirmed the presence of Candidatus Methylomirabilis oxyfera-like bacteria in all the examined sediments, while the group A members (the dominant bacteria responsible for N-DAMO) were found mainly in Hangzhou Bay. Quantitative PCR showed that the 16S rRNA gene abundance of Candidatus M. oxyfera-like bacteria varied from 5.4 × 10(6) to 5.0 × 10(7) copies g(-1) (dry sediment), with a higher abundance observed in Hangzhou Bay. In addition, the overlying water NO3 (-) concentration and salinity were identified as the most important factors influencing the abundance and potential activity of Candidatus M. oxyfera-like bacteria in the examined sediments. This study showed the evidence of N-DAMO in coastal environments and indicated the importance of N-DAMO as a potential methane sink in coastal environments.

Over the past few years, CuH-catalyzed hydroamination has been discovered and developed as a robust and conceptually novel approach for the synthesis of enantioenriched secondary and tertiary amines. The success in this area of research was made possible through the large body of precedent in copper(I) hydride catalysis and the well-explored use of hydroxylamine esters as electrophilic amine sources in related copper-catalyzed processes. This Minireview details the background, advances, and mechanistic investigations in CuH-catalyzed hydroamination.

The cycloaddition of epoxides with carbon disulfide proceeds effectively by using a binary catalyst system of tetradentate Schiff-base aluminum complexes (designated as salenAlX) as Lewis acid in connection with a nucleophilic co-catalyst, such as quaternary ammonium salt. The steric factor of the substituent groups on the aromatic rings of salenAlX and the anion of quaternary ammonium salt all have significant effects on the activity of the binary catalyst system, as well as the selectivities of the resultant cyclic products. The effects of temperature, time and the molar ratio of reactants were also investigated in detail with regard to propylene oxide with carbon disulfide, and a plausible mechanism was proposed. Copyright © 2012 John Wiley & Sons, Ltd.

Quaternary ammonium bases, such as aqueous (CH3)4NOH, were found to be an extraordinarily efficient catalyst for cyanosilylation of aldehydes. The addition reaction of trimethylsilyl cyanide (TMSCN) to equivalent aldehydes could proceed smoothly with turnover frequency (TOF) up to 3000000 h−1 and in near 100% yield under solvent-free conditions. These organic catalysts also tolerated various aldehydes including aromatic, aliphatic and α,β-unsaturated aldehydes. This process perfectly conforms to the features of green chemistry: no waste regarding side-products and unconverted reactants, solvent-free, excellent catalytic activity, and no requirement for separation.

A highly enantioselective transformation catalyzed by chiral (acyclic diaminocarbene)gold(I) complexes is reported. The enantioselective synthesis of 2-substituted chromenyl pivalates from racemic phenol-substituted propargyl pivalates was developed. Rearrangement of the substrates in the presence of cationic gold gave allene intermediates, whose cyclization resulted in formation of enantioenriched product through a dynamic kinetic asymmetric transformation.

Nano rice starch prepared by ultrasonic-assisted inverse suspension polymerization was investigated on its physicochemical, gel structure and morphology properties. Water solubility index (WSI) under different temperatures and water absorption index (WAI) of nano rice starch and native starch were studied in this paper. WAI of native starch was 8.67%, and that of nano starch increased 38.45%, compared with native starch. WSI of native starch was respectively 0.024%, 0.057%, 0.111%, 0.211% under 30°C, 40°C, 50°C, 60°C, however, that of nano starch respectively increased to 1.32%, 1.430%, 1.527%, 1.513%. Gel strength of nano starch was 3.20g, and native starch increased to 62.87g. The structure of native rice starch granules was polyhedron with pronounced edges, however, granule size of nano starch became small, and nano starch appeared significant agglomeration.

Lewis pair polymerization is a powerful method for preparing soluble polymers bearing pendant active vinyl groups by directly polymerizing dissymmetric divinyl polar monomers. Herein, we present a strategy for synthesizing block and brush copolymers via tandem Lewis pair polymerization of methacrylates, “thiol-ene” click reaction and organocatalytic ring-opening polymerization of lactide.

We have studied the electronic transport properties of an optical molecular switch based on the diarylethene molecule with two single-walled carbon nanotube (SWCNT) electrodes using first-principles transport calculations. It is shown that the closed form shows an overall higher conductance than the open form at low bias which is independent of the SWCNTs’ chirality. Meanwhile, the conductance of the molecular switch can be tuned by changing the chirality of the SWCNTs.

Fiber-optic DNA biosensors are a kind of ana-lytic setups, which convert the Waston-Crick base pairs matching duplex or Hoogsteen’s tri-plex (T/A-T, C/G-C) formation into a readable analytical signals when functionalized single- strands DNA (ssDNA) or double-strands DNA (dsDNA) of interest are immobilized on the sur-face of fiber-optic hybrids with target DNA or interacts with ligands. This review will provide the information about the fiber-optic DNA bio-sensors classified into two categories depend-ing on the end fiber and side fiber with or with-out the labels—label-free fiber-optic DNA bio-sensors and labeled fiber-optic DNA biosensor in recent years. Both are dissertated, and em-phasis is on the label-free fiber-optic DNA bio-sensors. Fiber-optic DNA biosensors had got great progresses because fiber-optic has more advantages over the other transducers and are easily processed by nanotechnology. So fiber- optic DNA biosensors have increasingly at-tracted more attention to research and develop the new fiber-optic DNA biosensors that inte-grated with the “nano-bio-info” technology for in vivo test, single molecular detection and on-line medical diagnosis. Finally, future pros-pects to the fiber-optic DNA biosensors are predicted.

Chiral chromium complexes of tetradentate N,N'-disubstituted bis(aminophenoxide) (designated as Salan, a saturated version of Schiff-base Salen ligand) in conjunction with an ionic quaternary ammonium salt can efficiently catalyze the copolymerization of CO 2 with racemic propylene oxide (rac-PO) at mild conditions to selectively afford completely alternating poly(propylene carbonate) (PPC) with ∼ 95% head-to-tail linkages and moderate enantioselectivity. These new catalyst systems predominantly exceed the previously much-studied SalenCr(III) systems in catalytic activity, polymer enantioselectivity, and stereochemistry control. The chiral diamine backbone, sterically hindered substitute groups on the aromatic rings, and the presence of sp 3 -hydridized amino donors and its N,N'-disubstituted groups in chiral SalanCr(III) complexes all play significant roles in controlling polymer stereochemistry and enantioselectivity. Furthermore, a relationship between polycarbonate enantioselectivity and its head-to-tail linkages in relation to regioselective ring-opening of the epoxide was also discussed on the basis of stereochemical studies of PPCs derived from the copolymerization of CO 2 with chiral PO at various conditions.

Canada, Australia and European countries, about 25% of deaths are related to malignant diseases. Chemotherapy is a central component in the fight against cancer. It is based on various classes of compounds, among which platinum-based drugs are a unique class. cis-Diamminedichloroplatinum(II) (cisplatin), first approved for clinical use in 1978 in the U.S.A., is one of the most effective anticancer drugs currently available for the treatment of testicular, lung and bladder carcinomas. Driven by the impressive impact of cisplatin on cancer therapy, numerous analogues have been prepared and evaluated in a search for alternative active agents, leading to the discovery of another important Pt drug, carboplatin, cis-diammine(1,1cyclobutanedicarboxylato)platinum(II) in 1986. Today, carboplatin has become one of the most successful anticancer drugs after cisplatin and has received worldwide approval for treating ovarian and small lung cancers (1, 2). Carboplatin shows a spectrum of activity identical with that of cisplatin, but is much less nephrotoxic and emetic. However carboplatin is not effective in treating cancer cells resistant to cisplatin, possibly due to the same diammine carrier, suggesting that crossresistance exists between the two Pt drugs (3, 4). Therefore, the search for new potent Pt complexes possessing high antitumour activity and lack of cross-resistance continues. The so-called ‘third generation’ Pt drug, oxaliplatin, (trans-1R,2Rcyclohexane-1,2-diamine)oxalatoplatinum(II), was approved in 1999 as the first line therapy for metastatic colorectal cancer in combination with 5-fluoroural. Oxaliplatin has also shown potency in many cancer cell lines, including some cells resistant to cisplatin and carboplatin (5). Further Pt-based drugs, nedaplatin, lobaplatin and eptaplatin, have gained regionally limited approval, respectively, in Japan, China and South Korea, for the treatment of certain kinds of cancers (6). Ptbased drugs currently in clinical use are shown in Figure 1. In the meantime, the rational design of Pt anticancer compounds with specific characteristics has led to the invention of the orally available drugs satraplatin (JM216) and picoplatin (AMD473, a sterically hindered complex), see

Adding the axial oscillation into the polymer plastic processing is the dynamic processing of polymer. There are two sections, the axial shearing section and the axial extrusion section, in the effect of vibration on the melting. The experiments show that the composites in the axial shearing section have a smaller mean particle diameter and a narrower particle size distribution, compared to those in the absence of vibration. So the vibration on melting ameliorates the filled properties of polymer composite. The experiments of the High-density polyethylene and Calcium carbonate (HDPE/CaCO3) filling system prove that the analyses are right.

Uniform bulk graft modification of vinyl monomers to polypropylene or polyethylene membranes was achieved by combining gamma (γ)-ray pre-irradiation-induced graft copolymerization and supercritical carbon dioxide (scCO 2 )-swelling polymerization techniques. In the first step, the polymer membranes were irradiated with γ-rays originated from cobalt-60 resource under oxygen or air atmosphere at ambient temperature, and thus potential active sites, hydroperoxides and diperoxides, were uniformly formed on the polymer backbone. Then, graft copolymerization of vinyl monomers such as styrene, N -vinylpyrrolidone ( N -VP), methyl methacrylate (MMA) and 2-hydroxyethyl methacrylate (HEMA) impregnated into polymer substrates with the aid of scCO 2 was initiated thermally within the host polymer by the polymer radicals (PO ) resulting from the decomposition of peroxides uniformly distributed in the irradiated polymer samples. The process parameters were controlled by the properties of the fluid phase (CO 2 /monomer mixture) and experimental conditions, such as monomer concentration, temperature and time. The bulk graft modification of polyolefin membranes was confirmed by element analysis, spectroscopy and microscopy.

A novel approach to uniformly bulk graft modification of pre-existing polymer materials without ungrafted homopolymers was achieved at relatively low temperature by means of gamma (γ)-rays pre-irradiation-induced “grafting-from” polymerization with supercritical carbon dioxide (scCO 2 ) both as solvent and as swelling agent. The polymer substrates were first irradiated with γ-rays originated from cobalt-60 resource under nitrogen atmosphere at ambient temperature, and thereby leading to uniform formation of trapped radicals on polymer backbone. Then, the produced polymer-trapped radicals were utilized to initiate graft polymerization of vinyl monomers dissolved in scCO 2 within polymer substrates. A combination of transmission electron microscopy, scanning electron microscopy and elemental analysis shows that side graft chains covalently bonded to polymer substrate backbone in nanometer scale are uniformly dispersed within polymer membranes with a thickness of 5 mm. Altering the experimental conditions can easily control the grafting yield with regard to side graft-chain length. This method can also be applied to various functional polymer chains covalently attached to different polymer substrates, even with high viscosity or limited solubility. The novel graft-polymer materials produced by this method are not formed in the absence of scCO 2 and are impossible to prepare by conventional methodologies.

This method uses a N-heterocyclic olefin/carbon dioxide adduct as organocatalyst for the synthesis of dioxolane derivatives.

To take advantage of the property of supercritical carbon dioxide as both a solvent and swelling agent, the bulk grafting of poly(styrene-alt-maleic anhydride) [P(MAH-alt-St)] onto preirradiated polyolefin membranes was performed by a combination of γ-ray-preirradiation-induced graft copolymerization and supercritical fluid-swollen polymerization. The trapped radicals on the polyolefin backbones were uniformly distributed by γ-ray irradiation under a nitrogen atmosphere. Subsequently, these polymeric trapped radicals initiated the alternating copolymerization of styrene (St) and maleic anhydride (MAH) infused into the swollen polymer matrix with the aid of supercritical CO2. It was important that the graft copolymers were relatively pure without any contaminants, including homopolymers, monomers, and initiators. The experimental results show that the degree of grafting could be easily controlled. In addition, St/MAH could synergistically promote the bulk grafting process and strongly effect on the alternating trend; this was confirmed by element analysis and differential scanning calorimetry. Soxhlet extraction, X-ray diffraction, and Fourier transform infrared spectroscopy indicated that the P(MAH-alt-St) was covalently bonded to the polymeric backbones. Scanning electron microscopy showed that the alternating graft chains were uniformly dispersed throughout the 5-mm thickness of the polymer membranes on the nanometer scale. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013

N-Heterocyclic carbene (NHC) functionalized MCM-41 was synthesized by reacting 1,3-bis-(4-allyl-2,6-diisopropylphenyl) imidazolium chloride with MCM-41 using 3-mercaptopropyltrimethoxysilane as silane coupling agent, and its CO2 adduct (designated as MCM-41-IPr-CO2) was further synthesized by the reaction with CO2. In situdiffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) was used to investigate the reversible CO2 capture-release ability of MCM-41-NHC. MCM-41-IPr-CO2 adduct proved to be an efficient heterogeneous catalyst for the cycloaddition of CO2 to epoxides or aziridines with excellent regioselectivity under mild conditions. Moreover, the catalyst could be recovered easily through a simple filtration process and reused multiple times without obvious loss in activity, owing to CO2 as protective group for effectively stabilizing the NHC anchored on MCM-41.

The development of the stone and formation of peach (Prunus persica) fruit were explored in this work using a proteomic approach. Sixty-eight proteins with different expression patterns were identified in both the endocarp and mesocarp during early fruit development (from 28 to 59 days after flowering) and the majority were involved in primary or secondary metabolism. In contrast to most proteins associated with primary metabolism in the endocarp, whose expression is down-regulated, expression of pyruvate dehydrogenase (PDH) unexpectedly increased exponentially. Moreover, its expression pattern was linearly positively correlated with the exponentially growing lignin content (R = 0.940), which suggests that PDH may play a role in endocarp lignification. Our data also revealed different spatiotemporal expressions of enzymes involved in the lignin and flavonoid pathways that provided proteome-level evidence to support the hypothesis that these two pathways are competitive during endocarp development. In addition, we observed endocarp-specific oxidative stress and propose that it may act as a stimulating factor in activating lignification and subsequent programmed cell death in the endocarp.

The last decade has witnessed dramatic growth in the number of reactions catalyzed by electrophilic gold complexes. While proposed mechanisms often invoke the intermediacy of gold-stabilized cationic species, the nature of bonding in these intermediates remains unclear. Herein, we propose that the carbon-gold bond in these intermediates is comprised of varying degrees of both sigma and pi-bonding; however, the overall bond order is generally less than or equal to unity. The bonding in a given gold-stabilized intermediate, and the position of this intermediate on a continuum ranging from gold-stabilized singlet carbene to gold-coordinated carbocation, is dictated by the carbene substituents and the ancillary ligand. Experiments show that the correlation between bonding and reactivity is reflected in the yield of gold-catalyzed cyclopropanation reactions.

The fluorescence from β- particle irradiation of cis- and trans-decalin containing benzene or toluene has been studied as a function of aromatic concentration from ⋍ 0.002 to 0.1 M and over a spectral range that encompasses both the solvent and aromatic fluorescence. By comparisons with the fluorescence obtained using sub-ionization excitation of the decalin, the effect of benzene and toluene to intrude into the geminate ion-pair decay process has been extracted and rate constants for their scavenging action obtained via fitting to the standard diffusion model. The rate constants are compared to those reported from microwave conductivity studies on the “escaped” mobile hole in these liquids. For the reaction between trans-decalin+ + toluene, the rates are in good agreement. However, for the reactions of either cis- or trans-decalin+ with benzene, the rate constants extracted from the fluorescence analysis are about an order of magnitude larger. The discrepancies suggest the existence of differences in the internal energies and structures of the decalin positive ions when observed on the very short time scale of geminate recombination (probed in the fluorescence measurements) and that which is observed on the much longer time scales that are probed in the microwave experiments. An analysis of the development of aromatic fluorescence permits extraction of the fraction of aromatic fluorescence that derives from ionic recombination (as opposed to energy transfer) and the averaged efficiency of this recombination. In all of the systems studied here the ionic fraction remains high (i.e. >;20%) even at millimolar concentrations of the aromatic.

Tetracyclines and tetracycline analogues are prepared by a convergent, single-step Michael-Claisen condensation of AB precursor 1 or 2 with D-ring precursors of wide structural variability, followed by removal of protective groups (typically in two steps). A number of procedural variants of the key C-ring-forming reaction are illustrated in multiple examples. These include stepwise deprotonation of a D-ring precursor followed by addition of 1 or 2, in situ deprotonation of a D-ring precursor in mixture with 1 or 2, and in situ lithium-halogen exchange of a benzylic bromide D-ring precursor in the presence of 1 or 2, followed by warming. The AB plus D strategy for tetracycline synthesis by C-ring construction is shown to be robust across a range of different carbocyclic and heterocyclic D-ring precursors, proceeding reliably and with a high degree of stereochemical control. Evidence suggests that Michael addition of the benzylic anion derived from a given D-ring precursor to enones 1 or 2 is quite rapid at -78 degrees C, while Claisen cyclization of the enolate produced is rate-determining, typically occurring upon warming to 0 degrees C. The AB plus D coupling strategy is also shown to be useful for the construction of tetracycline precursors that are diversifiable by latter-stage transformations, subsequent to cyclization to form the C ring. Results of antibacterial assays and preliminary data obtained from a murine septicemia model show that many of the novel tetracyclines synthesized have potent antibiotic activities, both in bacterial cell culture and in vivo. The platform for tetracycline synthesis described gives access to a broad range of molecules that would be inaccessible by semisynthetic methods (presently the only means of tetracycline production) and provides a powerful engine for the discovery and, perhaps, development of new tetracycline antibiotics.