A novel and facile strategy for highly flame retardant polymer foam composite materials: Transforming silicone resin coating into silica self-extinguishing layer.

In this study, a novel strategy was developed to fabricate highly flame retardant polymer foam composite materials coated by synthesized silicone resin (SiR) polymer via a facile dip-coating processing. Applying the SiR polymer coating, the mechanical property and thermal stability of SiR-coated polymer foam (PSiR) composites are greatly enhanced without significantly altering their structure and morphology. The minimum oxygen concentration to support the combustion of foam materials is greatly increased, i.e. from LOI 14.6% for pure foam to LOI 26-29% for the PSiR composites studied. Especially, adjusting pendant group to SiOSi group ratio (R/Si ratio) of SiRs produces highly flame retardant PSiR composites with low smoke toxicity. Cone calorimetry results demonstrate that 44-68% reduction in the peak heat release rate for the PSiR composites containing different R/Si ratios over pure foam is achieved by the presence of appropriate SiR coating. Digital and SEM images of post-burn chars indicate that the SiR polymer coating can be transformed into silica self-extinguishing porous layer as effective inorganic barrier effect, thus preserving the polymer foam structure from fire. Our results show that the SiR dip-coating technique is a promising strategy for producing flame retardant polymer foam composite materials with improved mechanical properties.

Development of novel chloroplast microsatellite markers for Miscanthus species (Poaceae).

PREMISE OF THE STUDY: A set of novel chloroplast microsatellite markers (cpSSRs) was developed for the bioenergy crop Miscanthus, and their utility in cross-species amplification was evaluated. METHODS AND RESULTS: Twenty-eight novel primers flanking cpSSR loci were designed from a complete chloroplast genome sequence of Saccharum officinarum, a species closely related to Miscanthus. These primers were then tested on eight Miscanthus species, among which 16 cpSSR loci were found to be polymorphic. The number of alleles per polymorphic locus ranged from two to seven, with an average 3.94 alleles. CONCLUSIONS: These cpSSR markers can be applied to all Miscanthus species and will be useful for studying Miscanthus population structure, diversity, and phylogeography.

Aromatic-amide-derived olefins as a springboard: isomerization-initiated palladium-catalyzed hydrogenation of olefins and reductive decarbonylation of acyl chlorides with hydrosilane.

A highly efficient catalytic protocol for the isomerization of substituted amide-derived olefins is presented that successfully uses a hydride palladium catalyst system generated from [PdCl(2)(PPh(3))(2)] and HSi(OEt)(3). The Z to E isomerization was carried out smoothly and resulted in geometrically pure substituted olefins. Apart from the cis-trans isomerization of double bonds, the selective reduction of terminal olefins and activated alkenes was performed with excellent functional group tolerance in the presence of an amide-derived olefin ligand, and the products were obtained in high isolated yields (up to >99 %). Furthermore, the palladium/hydrosilane system was able to promote the reductive decarbonylation of benzoyl chloride when a (Z)-olefin with an aromatic amide moiety was used as a ligand.

Organocatalytic aza-Michael/retro-aza-Michael reaction: pronounced chirality amplification in aza-Michael reaction and racemization via retro-aza-Michael reaction.

A detailed experimental investigation of an aza-Michael reaction of aniline and chalcone is presented. A series of Cinchona alkaloid-derived organocatalysts with different functional groups were prepared and used in the aza-Michael and retro-aza-Michael reaction. There was an interesting finding that a complete reversal of stereoselectivity when a benzoyl group was introduced to the cinchonine and cinchonidine. The chirality amplification vs. time proceeds in the quinine-derived organocatalyst containing silicon-based bulky group, QN-TBS, -catalyzed aza-Michael reaction under solvent-free conditions. In addition, we have demonstrated for the first time that racemization was occurred in suitable solvents under mild conditions due to retro-aza-Michael reaction of the Michael adduct of aniline with chalcone. These indicate the equilibrium of retro-aza-Michael reaction and aza-Michael reaction produce the happening of chirality amplification in aza-Michael reaction and racemization via retro-aza-Michael reaction under different conditions, which would be beneficial to the development of novel chiral catalysts for the aza-Michael reactions.

Neighboring lithium-assisted [1,2]-Wittig rearrangement: practical access to diarylmethanol-based 1,4-diols and optically active BINOL derivatives with axial and sp3-central chirality.

A facile and practical methodology for the synthesis of synthetically useful diarylmethanol-based 1,4-diols and enantiomerically pure BINOL-derived diols with axial and sp(3)-central chirality has been developed through neighboring lithium-promoted [1,2]-Wittig rearrangement. The chirality transfer process shows a broad substrate scope in terms of the aromatic ether substituent, which allows access to a broad of range of chiral 1,1'-binaphthalene-2-α-arylmethanol-2'-ols with excellent enantioselectivities (>99 % enantiomeric excess) and yields (84-96 %). This should be considered as an available and attractive chiral source to design and prepare privileged ligands or catalysts.

The recent synthesis and application of silicon-stereogenic silanes: a renewed and significant challenge in asymmetric synthesis.

The synthesis of silicon-stereogenic silanes is undoubtedly one of the most intriguing and challenging aspects in organic chemistry and organosilicon chemistry and is neglected by chemists to some extent. This critical review will focus on the recent exciting advances in the synthesis of silicon-stereogenic silane and outline the application of these chiral silanes in asymmetric synthesis (89 references).

Novel ladder π-conjugated materials--sila-pentathienoacenes: synthesis, structure, and electronic properties.

A novel series of ladder π-conjugated materials--sila-pentathienoacenes (Si-PTA) are synthesized and characterized. Crystal structures of the compounds show that the length of alkyl chains substituting on the thiophene ring has a significant influence on molecular packing. A densely packed structure with an interfacial distance of about 3.66 Å between the adjacent molecules is observed for the compound with shorter alkyl chains. However, a large interfacial distance (7.99 Å) is obtained for another compound because of the insertion of long alkyl chains between two planes. The investigation of the optical and electrochemical properties shows that the silylene bridge incorporated into the pentathienoacene framework exerts a clear effect on the electronic properties by the σ*-π* conjugation. Although only a slight enhancement is observed for the HOMO levels, with respect to that of pentathienoacene, the LUMO levels are significantly lowered. The observed electronic properties are consistent with the theoretical calculations.

Organocatalytic Michael addition of 1,3-dicarbonyl indane compounds to nitrostyrenes.

To map out the efficient organocatalyst requirements in the Michael addition of 1,3-dicarbonyl indane compounds to nitrostyrenes, a dozen different amino organocatalysts containing a p-toluenesulfonyl group (Ts) have been evaluated; excellent enantio-selectivities (up to er 92:8) were obtained with a primary amine-based Ts-DPEN catalyst and a plausible catalytic reaction mechanism was proposed on the basis of the experimental results.

[Study on phylogenetic relationships of urticaceae based on rbcL sequence].

The sequences of rbcL from four species of Boehmeria were analyzed in this study by PCR amplification and directly sequencing. The sequences of PCR products were about 1,370 bp. RbcL sequences of nine generas were chosen from GenBank, then the rbcL of 13 species were sequenced with clustal X1.83. After sequencing, the length of rbcL was 1,428 bp and has 1,263 conserved sites, 165 variable sites and 71 information sites. By using MEGA3.1, MP tree and NJ tree of Urticaceae were constructed. Based on the difference in rbcL squence, the genetic distances among species were calculated. With these informations, we can further analyze the genetic relationships of Urticaceae. In result, Pellionia, Poikilospermum, Procris, Elatostema and Pilea formed a monophyletic group; Parietaria and Boehmeria formed another monophyletic group. However, Urtica formed a single group, suggesting it had the most distant relationship to the other genus of Urticaceae.

[Quick testing-technology of transgenic rice with npt- screen marker gene].

By using npt-gene as assistant selection-marker, treating Japonica rice Zhonghua 9 [ZH9 (CK)] and transferred lysozyme gene rice (the donor rice is Japonica rice Zhonghua 9) [ZH9(R)] with antibiotics, we built a system of quickly testing transgenic rice offspring. Detached leaves of ZH9(R) and ZH9(CK) were treated by Kanamycin (0, 400, 450, 500, 550, 600 and 700 mg/L) and G418 (0, 40, 60, 80, 100, 150 and 200 mg/L) with different concentrations. The result show effect of Kanamycin is not evident and G418 is the best antibiotics to test transgenic rice with npt- gene. The data showed that 80 mg/L G418 (treating 4 d) was optimal to test transgenic rice. Further study was done with seeds, young embryos and seedlings by G418 testing: the alive seeds were cultured in the culture dishes which filled with a series of G418 solution with different concentration of 0, 100, 150, 200, 250, 300 and 350 mg/L; in the tissue culture room, the germinating embryos were inoculated in the culture medium (1/2 MS+0.5 mg/L 6-BA+1.5% sucrose) which contains G418 with 0, 150, 200, 250 and 300 mg/L concentration; the aseptic seedlings were inoculated in the the same culture medium (1/2 MS+0.5 mg/L 6-BA+1.5% sucrose) which contains G418 with 0, 100, 150, 200 and 250 mg/L concentration. The conclusions indicated that 300 mg/L (treating 7 d) was the critical concentration to test seeds of transgenic rice; 200 mg/L (treating 10 d) was the critical concentration to test young embryo of transgenic rice; 150 mg/L (treating 12 d) was the critical concentration to test seedlings of transgenic rice. Two primers were designed based on npt- and lysozyme gene sequences. PCR technology confirmed the above detection system. The preliminary results showed npt-was tightly linked with lysozyme gene. Above confirmed critical concentrations were applied to test detached leaves, seeds, young embryos and seedlings of transferred generations. The effect was very obvious. It is convenient, intuitionistic, and exact way that aparting the positive plants from the mixture of transgenic positive and negative plants with G418.

[Cloning and characterization of two beta-mannosidase cDNAs in Gossypium hirsutum L].

By using the method of PCR-based cDNA library screening, two beta-mannosidase clones, GhManA1 and GhManA2, had been isolated. GhManA1 had a length of 2692 bp coding for a polypeptide of 834 amino acids, and GhManA2 was 3209 bp which encoded a polypeptide of 976 amino acids. GhManA1 and GhManA2 shared an identical sequence of 747 amino acids in their carboxyl-terminals, but were distinctly different in their amino-terminals. Both beta-mannosidases were members of glycosyl hydrolase family 2, which had two conserved glutamine residues in their sequences as the acid-base catalyst and nucleophilic group, respectively. Most surprisingly, the first 93 amino acids in the amino-terminal of GhManA1 was highly homologous to the beta-barrel domain of ATP synthase alpha-/beta-subunit, but an analogous domain has never been found in the sequence of other non-ATP synthase protein. GhManA1 was constitutively expressed in different cotton tissues, and GhManA2 was specifically expressed in fiber cells.

Cloning and expression analysis of carboxyl-terminal protease cDNA from Gossypium hirsutum L.

A full-length cotton cDNA,designated GhCtp, was isolated from Gossypium hirsutum L. by the PCR-based cDNA library screening. The cDNA encodes a polypeptide of 473-amino acid residues. Sequence alignment showed that GhCtp was highly homologous to a family of carboxyl-terminal proteases (Ctp) from other species. GhCtp is a potential transmembrane protease, and comprises a conserved domain numbered DUF239 at its carboxyl-terminal and an arginine-rich region at the amino-terminal, respectively. Furthermore, there is a putative ATP-/GTP-binding site motif A (P-loop) in GhCtp which do not exist in Ctps of Arabidopsis and Oryza, indicating that GhCtp might function in a manner different from other Ctps. RT-PCR analysis suggested that GhCtp was not a fiber-specific or -preferential gene, and had a low expression level in different tissues or developmental stages of cotton.

Cloning and expression analysis of a bZIP cDNA in Gossypium hirsutum L.

A new full-length cDNA clone was isolated from the fiber cDNA library of Gossypium hirsutum L. The cDNA, designated GhbZIP,encoded a polypeptide of 645 amino acids. GhbZIP protein had the structure characteristics of plant bZIP proteins, including two conserved domains, DUF630 and DUF632 with unknown functions, a proline-rich domain and a phenylalanine-rich domain. Meanwhile, the protein contained a leucine zipper-like motif in DUF632. The hydropathy analysis showed that the GhbZIP was a membrane protein. GhbZIP gene was preferentially expressed in ovule and fiber cells since three days post-anthesis, as indicated it might be involved in the transcription regulation of genes during cotton fiber elongation.