Structure and properties of Ni(110) surface coadsorbing chlorine and oxygen

The coadsorption of chlorine with oxygen on Ni(110) surface has been investigated by XPS, UPS, AES and work function measurements. The chlorine preadsorption drastically inhibits the further uptake of oxygen. On the contrary, precovered oxygen has hardly any influence on the additional adsorption of chlorine due to the incorporation of precovered oxygen into the subsurface driven by the chlorine coadsorption. ARXPS measurements provide the evidence for this coadsorption model. The thermal desorption of chlorine and oxygen from the coadsorption surface is very similar to that of both individual adsorbates under the same heating conditions, but the desorption temperature of both the adsorbates apparently decreases on the coadsorption surface. The coadsorption and thermodesorption mechanisms are also discussed in detail.     

CHARACTERISTICS OF THE PRIMARY REACTION OF HYPOCRELLIN A PHOTOSENSITIZATION

The primary reaction of photosensitization of Hypocrellin A (HA) has been studied byusing techniques of ESR, spin-trapping and spin-counteraction. The experiments show thatHA is able to generate not only ~1O_2,but also O_2~-·OH and HA~- which are observed for thefirst time. The conversion of generating active oxygen into generating nonoxygen free rad-ical is confirmed as well. Based on the characteristics of the primary reaction which gene-rates these active substances (transient products), it is proposed that the photosensitized dam-age for the biological system by HA is probably related to not only ~1O_2 itself, but also amultiple effect from ~1O_2 as well as O_2~-,·OH and HA~+ free radical.     

Layer—by—layer Multilaryer Films Self—assembled from a Rare—earth—containing Poly—oxometalate,Na9[Eu（W5O18）2] and Poly （allylamine hydrochloride） and Their Photoluminescent Properties

Ultrathin multilayer films of a rare-earth-containing polyoxometalate Na9[Eu(W5O18)2](EW) and poly (allymamine hydrochloride)(PAH) have been prepared by layer-by-layer self-assembly from dilute aqueous solution.The fabrication process of the EW/PAH multilaryer films was followed by UV-vis spectroscopy and ellipsometry,which show that the deposition process is linear and highly reproducible from layer to layer.An average EW/PAH bilayer thickness of ca.2.1nm was determined by ellipsometry.In addition,the scanning electron microscopy(SEM) image of the EW/PAH film indicates that the film surface is relatively uniform and smooth.The photoluminescent properties of these films were also investigated by fluorescence spectroscopy.     

Detection of amyloid-beta by Fmoc-KLVFF self-assembled fluorescent nanoparticles for Alzheimer's disease diagnosis

The abnormal aggregation of amyloid-beta(Aβ) has been widely believed to play an important role in the pathogenesis of Alz heimer's disease(AD),which is also recognized as one of the main biomarkers for AD diagnosis.The peptide sequence Lys-Leu-Val-Phe-Phe(KLVFF) is considered as the main driver of the fibrillation of Aβ,which also can be utilized to target Aβ and inhibit its aggregation.In this study,KLVFF and Fmoc-KLVFF fluorescent nanoparticles were self-assembled through zinc coordination and π-πstacking.The recognition of Aβ aggregates including oligomers and fibrils by fluorescent nanoparticles can be realized through aromatic,hydrophobic,and hydrogen-bond interactions.The fluorescent nanoprobes can distinguish Aβ aggregation formats and detect Aβ at the limit of 1 pg/mL(S/N=3).Hence,the detection of Aβ aggregates by fluorescent peptide nanoparticles has great potential for AD diagnosis and progression prediction.     

Changes of conformation and aggregation state induced by binding of lanthanide ions to insulin

To clarify the mechanism of lanthanide ions (Ln3+) on the across-membrane transport of insulin and subsequent reducing blood glucose, the interactions of Ln3+with Zn-insulin and Zn-free insulin are investigated by spectroscopic methods. The results reveal that the binding of Ln3+ to insulin can induce its structure changes from secondary to quaternary structure, depending on the Ln3+ concentration. In the lower concentration, it triggers the conformational changes of insulin monomer in the binding region with insulin receptor (B(24-30)). It would affect insulin-insulin receptor interaction. Moreover, Ln3+ binding promotes the assembly of insulin monomer from dimer to polymer. The potency of Ln3+ in inducing insulin's aggregation is stronger than that of Zn2+. Furthermore, the aggregation can be reversed partly by EDTA-treatment, indicating that it is not due to denaturation. Similar to Zn2+ effect, Ln3+ can stabilize insulin hexamer in a certain range of concentration, but is stronger than the former.     

用于水蒸气重整生物质热解焦油的镍基催化剂的发展(英文)

Nickel catalysts are effective for the steam reforming of tar derived from biomass pyrolysis,but the improvement is needed in terms of activity,stability,suppression of coke deposition and aggregation,and regeneration.Our recent development of Ni-based catalysts for the steam reforming of tar is reviewed including the modification with CeO2(or MnO),trace Pt,and MgO.The role of additives such as CeO2,MnO,Pt,and MgO is also discussed.     

REFINED CRYSTAL STRUCTURE OF INSULIN AT 1.8A RESOLUTION——HYDROGEN BONDS AND BOUND WATER

The hydrogen bonds in insulin fall into three cases: the helical hydrogen bonds in α- or 3_(10)helices, the non-helical one formed by polar groups of insulin itself, and the hydrogen bondsformed between insulin and water. By using the information obtained, the results of a seriesof biochemical investigations on insulin analogs related to B-chain C-terminal peptide can beinterpreted and it can also be inferred that the complex behaviours of the aggregation ofinsulin may play a protective role for the unique conformation of the molecule. Water structure also appears in the refined model. About one third of the water in anasymmetric unit is hydrogen-bonded to insulin molecules or each other, which are referred toas bound water. The polar and charged groups of insulin all show the tendencies to bind towater molecules as many as possible, which is a significant factor for the stabilization of theunique conformation of the molecule. The binding way of water molecules to insulin mole-cules is also analysed.     

Novel Bone-targeted Agents for Treatment of Osteoporosis

The novel bone-targeted agents were designed and synthesized by the combination of raloxifene and bisphosphonates. The anti-osteoporosis effect was evaluated by bone mineral density (BMD) obtained from OVX mice in vivo. The results indicated that the compound 8, 9 not only prevented ovariectomy induced loss of bone but also enhanced BMD to 0.87% and 19.67% compared to Sham, respectively.     

Nondilute 1,2-dichloroethane solution of poly(9,9-dioctylfluorene-2,7-diyl): A study on the aggregation process

Molecular aggregates in conjugated polymer(CP) solution can propagate into mesoscale morphology of the relevant film and further dominate the optoelectronic property. Herein, we probed the aggregation behavior of poly(9,9-dioctylfluorene-2,7-diyl)(PFO) and studied its influence on the photophysical property in 1,2-dichloroethane(DCE) solution, where the contents of β-phase or-aggregates increased with prolonged aging time. Thereinto, high quality β-film was fabricated from DCE solution with critical aggregate time of 6 min. The film exhibited excellent surface morphology and characteristic emission of β-phase. Meanwhile, films prepared from aged DCE solutions exhibited high crystallinity, which was promising to obtain higher photoluminance efficiency and charge transport ability simultaneously. Therefore, it is significant to get deep insight into the aggregation behavior of CP, which is involved not only with the solution-processing technology of plastic device, but also with the optoelectronic property of CP.     

FUNCTIONAL ANALYSIS OF PROTEINS ON THE THYLAKOID MEMBRANE——EFFECTS OF Mg~(2+) AND BSA ON THE TRYPSIN-INDUCED CHLOROPHYLL a FLUORESCENCE AND THYLAKOID MEMBRANE SURFACE CHARGE CHANGES IN SPINACH CHLOROPLASTS

Trypsin digestion of spinach chloroplasts not only inhibits light-induced variable fluorescence yield (△F/F_0) but also abolishes Mg~(2+) stimulating effect on △F/F_0. If chloroplasts are incubated by Mg~(2+) prior to trypsin digestion, Mg~(2+) stimulating ability remains unchanged whereas the enzyme-induced △F/F_0 decline itself is not affected. The protective effect of pretreatment of chloroplasts with Mg~(2+) against trypsin closely correlated with alteration of the net negative charge on the outer surface of the thylakoid membrane by Mg~(2+). In contrast to this, addition of BSA to the chloroplast digested with trypsin significantly recovers the light-induced variable fluorescence yield but it does not influence Mg~(2+)-induced variable fluorescence change. The recovery effect of BSA incubation is not dependent upon Mg~(2+) concentration. Also, BSA does not alter the net negative charge on the outer surface of the thylakoid membrane.These results demonstrate the existence of two independent prote     

Design and Synthesis of New Arylsulfonamide and Arylamide Derivatives for the Platelet Aggression Inhibitor

A series of arylsulfonamide and arylamide derivatives have been prepared from anisole in good yields.The structures of those compounds were confirmed by ^H-NMR and MS analysis.Their activities against platelet aggregation were tested in vitro by using the Born test on rabbits.     

STUDIES ON THE RELATIONSHIP BETWEEN IR SPECTRA AND STRUCTURE OF SOME LINEAR Mo—Fe—S CLUSTERS.Ⅱ.LINEAR RELATIONSHIP BETWEEN SOME STRETCHING VIBRATION FREQUENCIES AND BOND DISTANCES

<正> The relationships between stretching vibration frequencies (v) and distances (r) of the bonds Mo-S and Fe-Cl in ten compounds have been investigated- It is found that vMO-S is linearly related to rMo-s. This provides a convenient method to obtained bond distance data for some cluster compounds whose molecular structures could not be determined by X-ray analyses, The linear relationship between vFe-cl and rFe-cl is also discussed. The near-linear relationships of vvs. rFe-Mo and vFe-sb vs. rFe-Mo demons-trate that the formation of Fe-Sb bond has an important influence on the formation of Fe-Mo bond and the Fe-Mo distance may be estimated from v values.     

纳米SnO2的非水溶剂溶胶-凝胶法制备与表征

Nanometer SnO₂ powders were successfully prepared by non-hydrolytic sol-gel approach combined with heat treatments using tin tetrachloride as starting material and ethylene glycol as solvent. The reaction mechanism of the sol-gel process is proposed. Results indicate that the -OHCH₂CH₂OH- prevent Cl^- ion from accessing to tin Sn⁴⁺ due to steric effect, and hence increaseing the stability of the sol solution. Ethylene glycol functions not only as a complextion agent to form a polymer network but also as a “spacer” to modulate the distance between metal ions, preventing metal oxide particles from aggregation during desiccation of the sol. The effects of heat treatments on the evolution of structure and morphology of nanosized SnO₂ powders were studied. The powders with narrow size distribution around 15～20 nm could be obtained at 500 ℃ for 4 h.     

SYNTHESIS AND MORPHOLOGICAL STRUCTURE OF POLY (PHENYLENE SULFIDE AMIDE)

Poly (phenylene sulfide amide) (PPSA) has been synthesized by using sulfur as Ssource which reacts with dichlorobenzamide (DCBA) and alkali in polar organic solvent atthe atmospheric pressure. The polymer structures were determined by elemental analysis,FT-IR and ~1H-NMR. It is shown that the yielded polymer has linear structure and itsstructure unit is -p-C_6H_4-CONH-p-C_6H_4-S-. The polymer morphology was studied byX-ray diffraction and polarized microscopy. The results show that PPSA is a crystallinepolymer and its spherulites are the aggregation of nontwisting lamella or micro-threadstructure. Under shearing force, these crystals are dispersed to form micro-fibrillarstructure. The decomposition kinetics of PPSA was also studied at different beating rates.The decomposition energy of PPSA is higher than that of PPS.     

Free Energy Change of Micelle Formation for Sodium Dodecyl Sulfate from a Dispersed State in Solution to Complete Micelles along Its Aggregation Pathways Evaluated by Chemical Species Model Combined with Molecular Dynamics Calculations

Surfactant molecules, when dispersed in solution, have been shown to spontaneously form aggregates. Our previous studies on molecular dynamics(MD) calculations have shown that ionic sodium dodecyl sulfate molecules quickly aggregated even when the aggregation number is small. The aggregation rate, however, decreased for larger aggregation numbers. In addition, studies have shown that micelle formation was not completed even after a 100 ns-long MD run(Chem. Phys. Lett. 2016, 646, 36). Herein, we analyze the free energy change of micelle formation based on chemical species model combined with molecular dynamics calculations. First, the free energy landscape of the aggregation, ?G_(i+j)~+, where two aggregates with sizes i and j associate to form the(i + j)-mer, was investigated using the free energy of micelle formation of the i-mer, G_i~+, which was obtained through MD calculations. The calculated ?G_(i+j)~+ was negative for all the aggregations where the sum of DS ions in the two aggregates was 60 or less. From the viewpoint of chemical equilibrium, aggregation to the stable micelle is desired. Further, the free energy profile along possible aggregation pathways was investigated, starting from small aggregates and ending with the complete thermodynamically stable micelles in solution. The free energy profiles, G(l, k), of the aggregates at l-th aggregation path and k-th state were evaluated by the formation free energy ∑_in_i( l,k)G_i~+ and the free energy of mixing ∑_in_i( l,k)k_BTln( n_i( l,k)/n( l,k)), where ni(l, k) is the number of i-mer in the system at the l-th i aggregation path and k-th state, with n(l,k)= ∑_n_i( l,k). All the aggregation pathways were obtained from the initial i state of 12 pentamers to the stable micelle with i = 60. All the calculated G(l, k) values monotonically decreased with increasing k. This indicates that there are no free energy barriers along the pathways. Hence, the slowdown is not due to the thermodynamic stability of the aggregates, but rather the kinetics that inhibit the association of the fragments. The time required for a collision between aggregates, one of the kinetic factors, was evaluated using the fast passage time, t_(FPT). The calculated t_(FPT) was about 20 ns for the aggregates with N = 31. Therefore, if aggregation is a diffusion-controlled process, it should be completed within the 100 ns-simulation. However, aggregation does not occur due to the free energy barrier between the aggregates, that is, the repulsive force acting on them. This may be caused by electrostatic repulsions produced by the overlap of the electric double layers, which are formed by the negative charge of the hydrophilic groups and counter sodium ions on the surface of the aggregates.     

Spatio-temporally resolved measurement of quantal exocytosis from single cells using microelectrode array modified with poly L-lysine and poly dopamine

The subsecond, temporal, vesicular exocytosis is ubiquitous, but difficult detecting in communication mechanisms of cells. A microelectrode array(MEA), fabricated by MEMS technology, was applied successfully for real-time monitoring of quantal exocytosis from single pheochromocytoma(PC12) cell.The developed MEA was evaluated by dopamine(DA) using electrochemical methods and the results revealed that the sensitivity of DA was improved to 12659.24 μA L mmol ~(-1)cm~(-2). The modified MEA was used to detect in vitro vesicular exocytosis of DA from single PC12 cells stimulated by concentrated100 mmol L~(-1)K~+cell solution. A total of 592 spikes were measured and analyzed by three parameters and the statistical results revealed the population of each parameter was an approximate Gaussian distribution, and on average, 1.31×10~6 ±9.25×10~4 oxidizable molecules were released in each quantal exocytosis. In addition, results also indicate that a single PC12 cell probably releases the spikes with T ranging from 25.6 ms to 35.4 ms corresponding to I_(max)ranging from 45.6 pA to 65.2 pA. The devices, including a homemade computer interface and the MEA modified with polymer film, provides a new means for further research on the neural, intercellular, communication mechanism.     

Investigation on photochromism of 1,2-bis(1,4-dimethyl-2-phenyl)perfluorocyclopentene

The photochromic diarylethene, 1,2-bis(1,4-dimethyl-2-phenyl)perfluorocyclopentene has been synthesized and its single crystal can be obtained in hexane at -4℃. The structure of diphenylperluorocyclopentene bearing C2/c space group and monoclinic crystal system is very different from that of dithienylperfluorocyclopentene derivatives bearing Pī space group and triclinic crystal system by X-ray crystallographic analysis. The compound undergoes the phototchromic reaction in solution but no optical activity in single crystal. In addition, its optimum conformation in solvent is also discussed.     

Theoretical studies on Ru(fppz)_2(CO)L (L=N-heterocyclic ligand):Electronic structure,absorption,phosphorescence,and solvatochromism

A series of ruthenium(II) complexes Ru(fppz)2(CO)L [fppz = 3-trifluoromethyl-5(2-pyridyl)pyrazole; L = pyridine (1), 4-dimethylaminopyridine (2), 4-cyanopyridine (3)] were designed and investigated theo-retically to explore their electronic structures, absorption, and emissions as well as the solvatochrom-ism. The singlet ground state and triplet excited state geometries were fully optimized at the B3LYP/LANL2DZ and CIS/LANL2DZ level, respectively. The HOMO of 1-3 is composed of dyz(Ru) atom and π(fppz). The LUMO of 1 and 2 is dominantly contributed by π*(fppz) orbital, but that of 3 is con-tributed by π*(L). Absorption and phosphorescence in vacuo, C6H12, and CH3CN media were calculated using the TD-DFT level of theory with the PCM model based on the optimized ground and excited state geometries, respectively. The lowest-lying absorption of 1 and 2 at 387 and 391 nm is attributed to {[dyz(Ru) π(fppz)] → [π*(fppz)]} transition, but that of 3 at 479 nm is assigned to {[dyz(Ru) π(fppz)] → [π*(L)]} transition. The phosphorescence of 1 and 2 at 436 and 438 nm originates from 3{[dyz(Ru) π(fppz)] [π*(fppz)]} excited state, while that of 3 at 606 nm is from 3{[dyz(Ru) π(fppz)] [π*(L)]} excited state. The calculation results showed that the absorption and emission transition character can be changed from MLCT/ILCT to MLCT/LLCT transition by altering the substituent on the L ligand. The phosphorescence of 1 and 2 does not have solvatochromism, but that of 3 at 606 nm (vacuo), 584 nm (C6H12), and 541 nm (CH3CN) is strongly dependent on the solvent polarity, so introducing elec-tron-withdrawing group on ligand L will induce remarkable solvatochromism.     

SEQUENCE STRUCTURE OF ETHYLENE-VINYL SUBSTITUTED COPOLYMER WITH ~(13)C NMR IV——CHLORINATED POLYETHYLENE

The substituent chemical shift (SCS) has been applied to the assignment of the ~(13)C NMRspectrum of chlorinated polyethylene (CPE). CPE of different chlorine contents has been em-ployed and their sequence structure discussed. The results show that characteristic of CPEwith medium chlorine content is the dichloroethane structure in molecular chain. SCS param-etets have been obtained from the ~(13)C NMR spectra. It was found that the effects of chlorinecontent and temperature on SCS are negligible, but the substituent parameter S_1 reduced by0.39 ppm when C_2Cl_4 was added to solvent ODCB.     

Effects of additives on the aggregation of surfactants: binding domination

The effects of electrolytes, alcohols, and urea on the aggregation of SDS, CTAB, and TritonX-100 at 25℃ have been investigated by fluorescence probing of pyrene. Both electrolytes and alcoholsreduce the critical micelle concentration (CMC) of the ionic surfactants, while the effect of the former ismore pronounced. It is shown that the effects of electrolytes mainly depend on the concentrationsand especially the valence of the opposite charge ions, and only slightly depend on the same charge ionsin respect of ion aggregate of micelle. The logarithm of CMC is not linearly correlated with theconcentrations of the counter ion or the electrolytes. The results are rationalized in terms of Hartley'smodel. Propanol increases the CMC of TX-100, while electrolytes and urea do not. In all the threekinds of surfactant micelles the excitation spectrum of pyrene slightly red-shifts (ca. 4 nm) from thatin water, but is not affected by the additives. The micropolarity of the environment in which pyrenemolecule resides in SDS micelle decreases with the increase of the concentrations of electrolytes. Thisis not the case when alcohols and urea were added to SDS or to TX-100. It is suggested that theaddition of electrolytes would result in more orderly orientation of SDS molecules. It is the bindingstrength of the counter ions that dominates the effects of additives on the aggregation of surfactants.