Novel Ba_(0.5)Sr_(0.5)Fe_(0.8)Zn_(0.2)O_(3-δ) membranes for POM

A novel cobalt-free perovskite based on Ba_(0.5)Sr_(0.5)Fe_(0.8)Zn_(0.2)O_(3-δ)(BSFZ)were prepared by EDTA-citric acid method.The lattice constants of the BSFZ perovskite were characterized by in situ high-temperature X-ray diffraction(HTXRD).The thermal expansion coefficient of BSFZ is 10.5×10~(-6)K~(-1),which is lower than that of cobalt-based perovskite materials.The BSFZ membrane was also used to construct reactors for the partial oxidation of methane(POM)to syngas.Results show that the BSFZ membrane...     

Bis(imino)pyridine–iron(II) complexes for ethylene polymerization

Ethylene polymerization was carried out using new late transition metal 2,6-bis(imino)pyridine catalysts containing different substituents (H, NO₂, and OCH₃) at the para position of the pyridine ring, activated by methylaluminoxane. Effects of polymerization parameters such as ethylene pressure, reaction temperature, hydrogen concentration and structure variation on the catalysts activities and polymer properties were investigated. Introducing the functionality in the para-position of the pyridine ring of the catalysts had remarkable effect on the polymer properties as well as the catalysts activities.     

Novel SrCe_(0.75)Zr_(0.20)Tm_(0.05)O_(3-δ) membrane for hydrogen separation

<正>Dense ceramic membranes with protonic and electronic conductivity have attracted considerable interest in recent years.In this paper,the powders of SrCe_(0.75)Zr_(0.20)Tm_(0.05)O_(3-δ) were synthesized via the liquid citrate method,and the membranes of SrCe_(0.75)Zr_(0.20)Tm_(0.05)O_(3-δ) were prepared by pressing followed by sintering.X-ray diffraction(XRD) was used to characterize the phase structure of both the powder and sintered membrane.The microstructure of the sintered membranes was studied by scanning electron microscopy(SEM).Hydrogen permeation through the SrCe_(0.75)Zr_(0.20)Tm_(0.05)O_(3-δ) membranes was carried out using gas permeation setup at 900℃.Hydrogen permeation flux of SrCe_(0.75)Zr_(0.20)Tm_(0.05)O_(3-δ) membrane reaches up to 0.042 mL/ min cm~2 at H_2 partial pressure of 0.4 atm.The hydrogen permeation fluxes obtained in this paper are similar to that of SrCe_(0.95)Tm_(0.05)O_(3-δ),and Zr doping can increase mechanical strength of SrCe_(0.75)Zr_(0.20)Tm_(0.05)O_(3-δ) membranes and the resistance to reducing circumstance.     

Polyethylenimine (PEI)g-comb-poly(ethylene glycol)-transferrin(I): Tumor-targeted Vector for Gene Delivery In-vitro

A new vector, PEG as a core, low Mw PEI was grafted to PEG, and transferrin was conjugated the co-polymer to form PEI-g-PEG-transferrin1,2. NMR, FT-IR and TGA spectroscopy confirmed the structures of activated PEG and the final products. The MW of PEI-g-P…     

Chemical Mechanical Planarization (CMP) for Microelectronic Applications

Surface planarity is of paramount importance in microelectronics. Chemical Mechanical Polishing (CMP) is the most viable approach to address the planarity issues during the fabrication of advanced semiconductor devices. With the integration of copper as interconnect and low k materials as dielectric, the CMP community is facing an ever increasing demand on reducing defectivity without scarifying production throughput. Key issues in CMP today include reduction of surface defectivity and enh…     

Tetra(acetylacetonato) tin(Ⅳ) as new catalyst for polytrimethylene terephthalate synthesis

<正>Chelate tetra(acetylacetonato) tin(Ⅳ) was prepared and used as catalyst for polytrimethylene terephthalate synthesis.It exhibited higher catalytic activity than tetrabutyl titanate,butyltinhydroxide oxide and dibutyltin oxide.Decrease in reaction time, content of terminal carboxyl group,color intensity and increase in intrinsic viscosity were observed.The unique molecular structure can be considered as factor remarkably improving the catalytic activity of tetra(acetylacetonato) tin(Ⅳ).     

MgCl(2)·4((CH(3))(2)CHCH(2)OH): A new molecular adduct for the preparation of TiCl(x)/MgCl(2) catalyst for olefin polymerization

A new molecular adduct of MgCl(2) with isobutanol, namely MgCl(2)·4((CH(3))(2)CHCH(2)OH) (MgiBOH), has been prepared as a precursor to the supporting material for an olefin polymerization catalyst. The MgiBOH adduct and final titanated Ziegler-Natta catalysts have been thoroughly characterized by powder XRD, thermal analysis, Raman spectroscopy and solid-state NMR for structural and spectroscopy aspects. A peak observed at 712 cm(-1) in the Raman spectra of MgiBOH indicates the characteristic Mg-O(6) breathing mode and the formation of the adduct. The diffraction feature at 2θ = 7.8° (d = 11.223 ?) in the XRD confirms the adduct formation and the layered structure. The aim of the present article is to study how the insertion of a bulky isobutanol moiety affects the structural and electronic properties of the MgCl(2)·isobutanol molecular adduct. Indeed, the focus of the present study is to explore how the presence of isobutanol, in the initial molecular adduct, influences the final Z-N catalyst properties and its activity.     

Heats of formation for Fe(CO)n(n=1–4)

The dissociation energies of Fe(CO)_n (n=2–4) are computed using correlation consistent basis sets and the CCSD(T) approach. The dissociation energies are extrapolated to the CBS limit and are corrected for core–valence (CV), scalar relativistic, spin–orbit, zero-point, and thermal effects. Our iron carbonyl bond strengths agree with experiment within the respective error bars. We use our dissociations energies at 298 K to obtain the heats of formation of Fe(CO)_n (n=1–4).     

Binding Constants for Terbium(Ⅲ) with Chicken Apoovotransferrin

ＩｎｔｒｏｄｕｃｔｉｏｎＴｈｅｔｒａｎｓｆｅｒｒｉｎｓａｒｅａｓｕｐｅｒｆａｍｉｌｙｏｆｍｅｔａｌ ｂｉｎｄｉｎｇｐｒｏｔｅｉｎｓ ,ｗｈｉｃｈａｒｅｓｉｎｇｌｅ ｃｈａｉｎｓ ,80ｋＤａｇｌｙｃｏｐｒｏｔｅｉｎｓ ,ｃｈａｒａｃｔｅｒｉｚｅｄｂｙｔｈｅｉｒａｂｉｌｉｔｙｔｏｂｉｎｄｉｒｏｎｔｉｇｈｔｌｙ(ａｎｅｆｆｅｃｔｉｖｅｂｉｎｄｉｎｇｃｏｎ ｓｔａｎｔｉｓａｂｏｕｔ 1 0 2 0 .7) ,ｂｕｔｒｅｖｅｒｓｉｂｌｙ[1,2 ] .Ｓｅｒｕｍｔｒａｎｓｆｅｒｒｉｎ ,ｆｏｕｎｄｉｎｂｌｏｏｄａｎｄｅｘｔｒａｃｅｌｌｕｌ…     

Cluster-models for uranyl(VI) adsorption on α-alumina

Aqueous complexation, adsorption, and redox chemistry of actinide species at mineral surfaces have a significant impact on their transport and reactive behavior in chemically and physically heterogeneous environments. The adsorption configurations and energies of microsolvated uranyl dication species, UO(2)(H(2)O)(n)(2+), were determined on fully hydroxylated and proton-deficient α-alumina(0001)-like finite cluster models. The significant size of the models provides faithful representations of features that have emerged from periodic calculations, but most importantly, they afford us a systematic study of the adsorption mechanism, the effect of secondary solvation shells and an explicit treatment of the total charge. Based on this cluster representation, the energetics computed from the difference between the optimized structures and the appropriate reference states point to a preference for an inner-sphere type complex.     

Synthesis of PEGylated hyaluronic acid for loading dichloro(1,2-diaminocyclohexane)platinum(Ⅱ)(DACHPt) in nanoparticles for cancer treatment

Dichloro(1,2-diaminocyclohexane)platinum(II)(DACHPt), a cisplatin(CDDP) analog, has shown lower toxicity than CDDP and no cross-resistance with CDDP in many CDDP-resistant cancers. PEGylated hyaluronan(m PEG-HA) is an m PEG conjugated with hyaluronan biodegradable polymer which is a naturally occurring biopolymer in the interstitium, is primarily cleared by the lymphatic system. m PEGhyaluronan–DACHPt(PEG-HA–Pt) conjugate could circulate long-term in the bloodstream and increase DACHPt concentration in the tumor site and decrease systemic toxicity. m PEG-HA conjugates with the range of 1%–5% substitution were synthesized, and the structures were confirmed by1 H NMR and IR. The particle size of DACHPt incorporated with m PEG-HA was about 86 nm and the loading content and efficiency were about 19%(w/w) and 86%, respectively. The synthesized m PEG-HA with different PEG substitution degrees presented non toxicity, and the cell viability of DACHPt loaded in m PEG-HA nanoparticles increased with increasing doses of DACHPt. DACHPt release from nanoparticles slightly decreased with increasing PEG substitution degree from 1% to 5% at 37 8C, pH 7.4 PBS solution. The DACHPt loaded in m PEG-HA nanoparticles significantly inhibited the growth of A549 xenografts in nude mice when compared to the DACHPt loaded in HA nanoparticles and the control group after 4 weeks treatment(p 0.01 compared with control). The body weight change curve shows that the mice weight loss was less than 5% by treating with both DACHPt loaded in m PEG-HA and HA nanoparticles. In conclusion, a novel DACHPt loaded m PEG-HA delivery system was developed with sustained release and increased platinum concentration in the tumor.     

A new shortcut synthesis route for (±)raphidecursinol

<正>The new shortcut synthesis route of(±)raphidecursinol 1,a racemic 8,4′-oxyneolignan compound,can be more easily achieved by the synthesis route,starting from readily available inexpensive 3,4,5-trimethoxybenzaldehyde and 1,2,3-trihydroxybenzene.All structures were confirmed by ~1H NMR,IR and MS.     

Structure and stability for (AlN)_n~+ and (AlN)_n~- (n=1-15) clusters

Using density functional theory (DFT) method with 6-31G* basis set, we have carried out the optimizing calculation of geometry, vibrational frequency and thermodynamical stability for(AIN)n+ and (AIN)n- (n =1-15) clusters. Moreover, their ionic potential (IP) and electron affinity(EA) were discussed. The results show that the electrical charge condition of the cluster has a relatively great impact on the structure of the cluster and with the increase of n, this kind of impactis reduced gradually. There are no AI-AI and N-N bonds in the stable structure of (AIN)n+ or (AIN)n-, and the AI-N bond is the sole bond type. The magic number regularity of (AIN)n+, and (AIN)n- is consistent with that for (AIN)n, indicating that the structure with even n such as 2, 4,6, … is more stable. In addition, (AIN)10 has the maximal ionization power (9.14 eV) and the minimal electron affinity energy (0.19 eV), which manifests that (AIN)10 is more stable than other clusters.     

Theoretical designs for germaacetylene (RC≡GeR'): a new target for synthesis

The effect of substitution on the potential energy surfaces of RC≡GeR (R = F, H, OH, CH(3), SiH(3), Tbt, Ar*, SiMe(SitBu(3))(2) and SiiPrDis(2)) was explored using density functional theories (B3LYP/LANL2DZdp and B3PW91/6-31G(d)). Our theoretical studies indicate that all the triply bonded RC≡GeR species prefer to adopt trans-bent geometry, which is in agreement with the theoretical model (mode (B)). Additionally, we show that the stabilities of the RC≡GeR species bearing smaller substituents (R = F, H, OH, CH(3) and SiH(3)) decrease in the order R(2)C=Ge: > RC≡GeR > :C=GeR(2). On the other hand, the triply bonded RC≡GeR molecules with bulkier substituents (R = Tbt, Ar*, SiMe(SitBu(3))(2), SiiPrDis(2)) were found to possess the global minimum on the singlet potential energy surface and are both kinetically and thermodynamically stable. That is to say, both electronic and steric effects of bulky substituents play a crucial role in making triply bonded germaacetylenes (RC≡GeR) an interesting synthetic target.     

Versatile Approach for the Asymmetric Synthesis of (R)‐ and (S)‐Massoialactones

A general synthetic approach to both enantiomers, (R)‐ and (S)‐massoialactones, has been devised from commercially available (S)‐butane‐1,2,4‐triol.     

Crystalline metallic Au nanoparticle-loaded α-Bi(2)O(3) microrods for improved photocatalysis

Crystalline metallic Au nanoparticles were loaded on α-Bi(2)O(3) microrods (Au/α-Bi(2)O(3)) using an Au deposition-precipitation method. The prepared samples were characterized by scanning electron and transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, and UV-vis diffuse reflectance spectroscopy. Upon visible light irradiation, the Au/α-Bi(2)O(3) exhibits much higher photocatalytic activities than the pure α-Bi(2)O(3) for the degradation of Rhodamine B and 2,4-dichlorophenol in aqueous solution. The role of the Au and the paths of electron transport in the photocatalysis of the Au/α-Bi(2)O(3) were investigated and discussed in detail based on the analysis of the photo-generated hydroxyl radicals (˙OH) and hydrogen peroxide (H(2)O(2)) in the visible light irradiated suspension of pure α-Bi(2)O(3) and Au/α-Bi(2)O(3). The result reveals that the Au loaded on α-Bi(2)O(3) plays a critical role in the separation of the electron and hole pairs by accumulating the electrons from the excited α-Bi(2)O(3), which is responsible for the enhanced photocatalytic activity.