Influence of isopropyl tris(dioctylphosphoryloxy) titanate for flame-retardant TPU based on oyster shell powder

The flammability and droplet properties of thermoplastic polyurethane (TPU) have limited its wide application in many fields. In this article, isopropyl tris(dioctylphosphoryloxy) titanate was selected as synergism and compatilizer with oyster shell powder as flame retardant in TPU composites. And the influence of isopropyl tris(dioctylphosphoryloxy) titanate for flame-retardant TPU composites has been intensively investigated using the smoke density test, the cone calorimeter test, and the thermogravimetric analysis/infrared spectrometry, respectively. The test results show that isopropyl tris(dioctylphosphoryloxy) titanate can reduce the smoke production and heat release. And the total smoke production was reduced by 32% when the mass fraction of isopropyl tris(dioctylphosphoryloxy) titanate was 0.1%. The above results indicate that isopropyl tris(dioctylphosphoryloxy) titanate has a good application prospect in reducing the risk of TPU combustion.

     

Atomic force microscopy and enzymatic degradation of oyster shell protein and poly(aspartate)

Oyster shell protein (OSP), an aspartate-enriched regulator of crystallization, was readily observed in its natural condition by atomic force microscopy (AFM) of fragments of oyster shell. The fragments of shell consisted of layers of calcite mineral, termed folia, to which arrays of protein molecules are attached. Modification and removal of the OSP following treatment with several proteolytic enzymes such as subtilisin, carboxypeptidase B, and endoproteinase Glu-C were also observed by AFM. Similarly, poly (aspartate), a polypeptide analog of the OSP, was visualized by AFM on both calcite and mica. Images of poly(aspartate) before and after treatment with lipase demonstrated the potential utility of AFM in degradation studies. The mechanism of hydrolysis is not clear in that lipase normally is considered to be an esterase and not a peptidase.     

Al-Y共掺杂对ZnO纳米棒形成及光催化活性的影响

以Zn(NO3)2·6H2O,Al(NO3)3·9H2O,Y(NO3)3·6H2O和Na OH为原料,采用溶液法制备了Al-Y共掺杂Zn O光催化剂(Al-Y/Zn O),并用X射线衍射(XRD)、扫描电镜(SEM)考察了Al,Y共掺杂对Zn O纳米棒形成及形貌的影响。结果表明,Al-Y共掺杂对Zn O晶粒大小基本没有影响,但会严重抑制Zn O纳米棒的生成,促使碱式硝酸锌(Zn5(OH)8(NO3)2·2H2O)的生成。以甲基橙(MO)为模型污染物考察了Al-Y共掺杂对Zn O纳米棒光催化活性的影响。结果发现,适量的Al-Y共掺杂会显著提高Zn O纳米棒的光催化活性。     

Calcined oyster shell nanoparticles (COS NPs): a new,efficient and reusable catalyst for one-pot rapid preparation of 1,8-dioxo-octahydroxanthenes under solvent-free conditions

Research on Chemical Intermediates - Calcined oyster shell nanoparticles (COS NPs) as a novel heterogeneous nanocatalyst were prepared and fully characterized by X-ray fluorescence analysis,...     

Biosynthesis of TiO2 Nanoparticles Using Edible Mushroom (Pleurotus djamor) Extract: Mosquito Larvicidal,Histopathological, Antibacterial and Anticancer Effect

Journal of Cluster Science - The titanium dioxide nanoparticles (TiO2NPs) were synthesized by the aqueous extract from P. djamor. The UV–Vis spectrum of TiO2NPs showed maximum absorption at...     

Linear nanostructure formation of aldehydes by self-directed growth on hydrogen-terminated silicon(100)

The self-directed growth of organic molecules on silicon surfaces allows for the rapid, parallel production of hybrid organic-silicon nanostructures. In this work, the formation of benzaldehyde- and acetaldehyde-derived nanostructures on hydrogen-terminated H-Si(100)-2x1 surface is studied by scanning tunneling microscopy in ultrahigh vacuum and by quantum mechanical methods. The reaction is a radical-mediated process that binds the aldehydes, through a strong Si-O covalent bond, to the surface. The aldehyde nanostructures are generally composed of double lines of molecules. Two mechanisms that lead to double line growth are elucidated.     

Effect of antifreeze proteins on the nucleation, growth, and the memory effect during tetrahydrofuran clathrate hydrate formation

The inhibition activities of two antifreeze proteins (AFPs) on the formation of tetrahydrofuran (THF) clathrate hydrate have been tested. AFPs from fish (wfAFP) and insect (CfAFP) changed the morphology of growing THF hydrate crystals. Also, both AFPs showed higher activities in inhibiting the formation THF hydrate than a commercial kinetic inhibitor, poly(vinylpyrrolidone) (PVP). Strikingly, both AFPs also showed the ability to eliminate the "memory effect" in which the crystallization of hydrate occurs more quickly after the initial formation. This is the first report of molecules that can inhibit the memory effect. Since the homogeneous nucleation temperature for THF hydrate was measured to be 237 K, close to that observed for ice itself, the action of kinetic inhibitors must involve heterogeneous nucleation. On the basis of our results, we postulate a mechanism for heterogeneous nucleation, the memory effect and its elimination by antifreeze proteins.     

Cloning,Expression, and Characterization of a Milk-Clotting Aspartic Protease Gene (Po-Asp) from Pleurotus ostreatus

An aspartic protease gene from Pleurotus ostreatus (Po-Asp) had been cloned based on the 3′ portion of cDNA in our previous work. The Po-Asp cDNA contained 1,324 nucleotides with an open reading frame (ORF) of 1,212 bp encoding 403 amino acid residues. The putative amino acid sequence included a signal peptide, an activation peptide, two most possible N-glycosylation sites and two conserved catalytic active site. The mature polypeptide with 327 amino acid residues had a calculated molecular mass of 35.3 kDa and a theoretical isoelectric point of 4.57. Basic Local Alignment Search Tool analysis showed 68–80 % amino acid sequence identical to other basidiomycetous aspartic proteases. Sequence comparison and evolutionary analysis revealed that Po-Asp is a member of fungal aspartic protease family. The DNA sequence of Po-Asp is 1,525 bp in length without untranslated region, consisting of seven exons and six introns. The Po-Asp cDNA without signal sequence was expressed in Pichia pastoris and sodium dodecyl sulfate-polyacrylamide gel electrophoresis demonstrated the molecular mass of recombinant Po-Asp was about 43 kDa. The crude recombinant aspartic protease had milk-clotting activity.     

Thermal and spectral behavior of (Y,Eu)VO4 powder

Thermal analysis of Y_xEu_1?xVO₄ powder (used as “phosphor” coating for a high pressure mercury lamp) was done under a non-isothermal linear regime, both in a dynamic air regime and in a nitrogen atmosphere. The heating in air atmosphere gave on TG curve small rate of mass increase due to oxygenation and two endothermic effects are observed on DTA and DSC curves. By contrary, in nitrogen atmosphere a continuous stepped mass loss of powder (around 0.65 %), is recorded in the range of temperatures from room temperatures to 1,200 °C, and only one endothermic effect, to eliminate the gases accumulated on the crystallite surface. The powder was heated for 3 h in a Nabertherm furnace at 350, 800, and 1,100 °C using quite similar rate for heating program followed by a furnace cooling to room temperature. XRD and FTIR analyses showed the sample purification by thermal treatment and a very small increase of nanocrystallite sizes. The time evolution of the optical emission spectra in the range from 186.2 to 877.47 nm were recorded for different lamp powers in two different situations: with the outer bulb coated with Y_xEu_1?xVO₄ type “phosphor”, and without it. We observed that UV-Hg lines are absorbed by Y_xEu_1?xVO₄ type “phosphor” with different percents (100 % for 253.73 nm, 95 % for 312.65 nm, and 33 % for 365.12 nm) but the heating of the powder do not influence the UV-absorption properties of the powder.     

Effect of support and reactant on the yield and structure of carbon growth by chemical vapor deposition

The effect of catalyst support and reactant on the yield and structure of carbon growth has been investigated in the chemical vapor deposition (CVD) process. Powder Fe and Fe/Al(2)O(3) were the catalysts studied, and CO/H(2), CO, CH(4), and C(2)H(6)/H(2) were used as gas precursors. Platelet and fishbone-tubular structures were produced on powder and supported Fe from CO/H(2), with average diameters of 115 and 45 nm and yields of 28.8 and 17.6 g of C/g of cat. in 8.5 h, respectively. Onionlike carbon was the main structure produced from pure CO on both catalysts. In contrast, from hydrocarbons the highest yield of 2.24 g of C/g of cat. was achieved on Fe/Al(2)O(3), with predominantly tubular structures produced and average tube diameters close to 21 nm. It is concluded that the reactivity and carbon nanostructures are dictated by the size and crystallographic orientation of the catalyst particles. It has been suggested that the tubular structures were grown by continuous carbon supply directly to the tube, but the fiber structures were grown in a layer-by-layer manner. Controlled synthesis of carbon nanotube, platelet nanofiber, fishbone-tubular nanofiber, and onionlike carbon with high selectivity and yield was demonstrated.     

Effect of acid on the quantum yield of photodissociation of 9-(4-azidophenyl)acridine

The quantum yield of photodissociation of 9-(4-azidophenyl)acridine (1) is equal to 0.82, and that of its protonated form 2 is 6.9·10⁻³. The observed quantum yield of the system can smoothly be controlled in these limits varying the acidity of the medium. According to quantum chemical data, reactivity difference between neutral azide 1 and cation 2 is caused by the fact that in the lowest singlet-excited state (S₁) of azide 1 the antibonding σ*_NN molecular orbital is occupied, while this orbital remains unoccupied in the excited state of cation 2. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 12, pp. 2655–2660, December, 2005.     

Preparation and characterization of Ag(Au) bimetallic core–shell nanoparticles with new seed growth method

Ag(Au) bimetallic core–shell nanoparticles were prepared by a new seed growth method. Ascorbic acid was used to reduce the complex of HAuCl₄ and hexadecyltrimethylammoniumbromide (CTAB). This resulted in the forming of colorless Au(I) (AuCl₂⁻). It was used as the growth solution to prepare these bimetallic core–shell nanoparticles. These nanoparticles were characterized by UV–vis spectroscopy, transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). The results showed these nanoparticles exhibited core–shell shape and there was large amount of Ag in the shell. These nanoparticles could be produced in a few minutes without violent stirring and the method was easy and convenient compared with others. The effect of amount of AuCl₂⁻ on the shape of nanoparticles was also studied. Many small gold nanoparticles were formed on the surface of bimetallic core–shell nanoparticles in the presence of excess AuCl₂⁻. The mechanisms were also proposed to explain the process of colloidal preparation.     

Effect of stereocomplex formation between enantiomeric poly(l,l-lactide) and poly(d,d-lactide) blocks on self-organization of amphiphilic poly(lactide)-block-poly(ethylene oxide) copolymers in dilute aqueous solution

The effect of crystallization of a hydrophobic poly(lactide) block on the self-organization of biocompatible and biodegradable amphiphilic poly(lactide)-block-poly(ethylene oxide) (PLA-b-PEO) copolymers in a dilute aqueous solution has been investigated. It was demonstrated that the co-crystallization of poly(L,L-lactide) [P(L,L)LA] and poly(d,d-lactide) [P(d,d)LA] chains under equimolar mixing of P(L,L)LA₄₆-b-PEO₁₁₃ and P(d,d)LA₅₆-b-PEO₁₁₃ copolymers resulted in the formation of stable and spontaneously water-redispersible stereocomplex micelles with semicrystalline P(L,L)LA/P(d,d)LA cores. It was shown that the P(L,L)LA₄₆ / P(d,d)LA₅₆-b-PEO₁₁₃ stereo-complex micelles produced by dialysis can be potential vehicles for the anticancer agent oxaliplatin     

Acetylene coupling on Cu(111): formation of butadiene, benzene, and cyclooctatetraene

Acetylene trimerizes to benzene on the (111) face of copper, as it does on the (100) and (110) planes. However, Cu(111) also yields butadiene and cyclooctatetraene, the latter never previously found with Cu or any other material. No coverage threshold is observed for the onset of these coupling reactions, implying high adsorbate mobility: gaseous benzene is formed by a surface reaction rate-limited process, whereas butadiene and cyclooctatetraene are formed by desorption rate-limited processes. H/D isotope tracing shows that benzene formation proceeds via a statistically random associative mechanism, whereas butadiene formation is associated with strong kinetic isotope effects, probably associated with C-H cleavage. A pericyclic mechanism involving dimerization of C4H4 metallocycles is proposed to account for the formation of cyclooctatetraene. We also found that approximately 45 nm alpha-alumina supported copper particles operated under catalytic conditions at atmospheric pressure yield the same principal reaction products as those found with Cu(111) under vacuum conditions. It therefore seems likely that the elementary reaction steps that describe the surface chemistry of the model system are also important under practical conditions. Comparison of the structure, bonding, and reactivity of acetylene on Cu(111) and Pd(111) indicates that the effectiveness of copper in promoting C-H cleavage in adsorbed acetylene is associated with greater rehybridization of the C-C bond with concomitant weakening of the C-H bond.     

Effect of hydrogen-bonding interactions on the self-assembly formation of sodium N-(11-acrylamidoundecanoyl)-L-serinate, L-asparaginate, and L-glutaminate in aqueous solution

Aggregation behavior of three N-acyl amino acid surfactants, sodium N-(11-acrylamidoundecanoyl)-l-serinate (SAUS), sodium N-(11-acrylamidoundecanoyl)-l-asparaginate (SAUAS), and sodium N-(11-acrylamidoundecanoyl)-l-glutaminate (SAUGL), was studied in aqueous solution by use of surface tension, fluorescence, dynamic light scattering, and transmission electron microscopic techniques. The amphiphiles have been shown to initially form flexible bilayer structures, which upon increase of surfactant concentration transform into closed spherical vesicles. The transmission electron micrographs of the aqueous solutions of the surfactants confirmed the existence of spherical vesicles. Dynamic light scattering measurements were performed to obtain hydrodynamic radii of the vesicles. Circular dichroism spectra of the amphiphiles indicated formation of chiral helical aggregates in the case of SAUS. The self-assembly formation of the amphiphiles has been discussed in light of the intermolecular hydrogen bonding interaction of the amide groups.     

Effect of complex formation in the dioxyethane-Eu(fod)3-ketone system on europium(III) deactivation processes

It was established that the quenching of Eu(fod)₃ ^* luminescence by dioxyethanes is chemical in character and caused by formation of [dioxyethane...Eu(III)] complexes. A -metric method was proposed for testing the possibility of catalysis of thermal decomposition of dioxyethanes by lanthanide ions and for monitoring dynamics of complex formation in the dioxyethane-lanthanide-ketone chemiluminescent system.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 8, pp. 1745–1750, August, 1990.     

Ultrathin-film growth of para-sexiphenyl (II): formation of large-size domain and continuous thin film

The large-size domain and continuous para-sexiphenyl (p-6P) ultrathin film was fabricated successfully on silicon dioxide (SiO2) substrate and investigated by atomic force microscopy and selected area electron diffraction. At the optimal substrate temperature of 180 degrees C, the first-layer film exhibits the mode of layer growth, and the domain size approaches 100 microm(2). Its saturated island density (0.018 microm(-2)) is much smaller than that of the second-layer film (0.088 microm(-2)), which begins to show the Volmer-Weber growth mode. The characteristic of liquid-like crystal of p-6P monolayer film and the adequate diffusion of p-6P molecules dominate the formation of large-size domain. The coalescence of large-size domains offers the possibility to grow high-quality p-6P monolayer film which provides excellent substrate for weak epitaxy growth of phthalocyanine compounds.