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The dissociation of a single water molecule on a ZnO(101̅0) surface has been investigated at the atomic level by low temperature STM manipulation combined with DFT calculations. The positive pulses applied from the tip inject electrons into the system and break the bonding between water and the ZnO surface, thus leading to the hopping of water molecules. Negative pulses inject holes wherein the lower energy ones split the free O-H bond pointing out of the surface whereas the higher energy ones split the second O-H bond that is directed to the surface through hydrogen bonding. Moreover, the yielded proton and hydroxyl species present distinctly charged status through different reaction pathways, manifesting their unique impacts on tailoring the surface properties of the metal oxide.

Activation of hydrogen on oxide surface is of both practical and fundamental importance for broad fields of syngas-based chemical industries as well as clean energy utilizations. Previously we found ZnO can catalyze the heterolysis of H2, which only occurs at low temperatures (

Strong metal–support interaction (SMSI) has long been studied in catalytic reactions. Proper utilization of the SMSI effect might not only improve the stability of the catalysts, but also the activity and selectivity. In this work, using the atomic layer deposition (ALD) technique, we synthesized a series of Pd/ZnO catalysts with Pd particle sizes ranging from 1.6 to 7.9 nm. Upon H2 reduction at elevated temperatures, these Pd/ZnO catalysts display a size-dependent SMSI effect wherein the larger-size Pd particles are more prone to be encapsulated by ZnO compared to the smaller ones. In the reaction of CO2 hydrogenation, we show that such size-dependent SMSI, together with the size-related CO binding strength on Pd particles, provides a higher activity and methanol selectivity to the Pd particles larger than ~2.5 nm.

The adsorption of formic acid on a ZnO(1 0 −1 0) surface has been investigated with low temperature scanning tunneling microscopy (LT-STM) in combination with density-functional theory (DFT) calculations. Through high resolution STM images and in-situ exposure experiments we clearly identify that the formic acid dissociates upon adsorption even at liquid nitrogen temperature. DFT calculations reveal a preferential bidentate configuration of the formate species with the molecular plane orientating along the [1 −2 1 0] direction, while the yielded surface hydroxyl has two kinds of anchoring sites with similar energy. At elevated temperature, the adsorbed molecules were found to accumulate into short chains consisting exclusively of formate and hydroxyl and orienting along the [0 0 0 1] direction, which finally assemble into a (2 × 2) superstructure at half monolayer coverage. Careful examination of the defect structure of the saturation coverage film revealed the existence of monodentate adsorption states of formic acid but with very small probability. These results have clarified the inconsistent propositions from different spectroscopic studies. Moreover, the preferential ordering of the formate species may bring fresh insights into the understandings of the related surface reactions through formate intermediates.

Molybdenum disulfide (MoS2) has attracted considerable interest due to its superior electronic and optical properties, which have seen promising applications in optoelectronics and catalysis. Chemi...

Low temperature scanning tunneling microscopy (LT-STM) has been applied to investigate the adsorption of acetylene (C2H2) on the rutile TiO2(110) surface at 77 K. Through in situ exposing and ex situ annealing experiments we unambiguously demonstrate that C2H2 molecules adsorb weakly on top of the Ti5c ions. Moreover, our data clearly reveal that the oxygen vacancy (Ov) cannot directly adsorb C2H2 molecules but can activate its next-nearest Ti5c ions which register as a binding site for C2H2 molecules with enhanced stability. Further increasing the C2H2 coverage leads to the stepwise formation of c-(4 × 2) and c-(2 × 2) ordered structures before final saturation at around 0.68 monolayer. The saturated film is characterized by dominating C2H2 dimers and other minority linear clusters whose intermolecular distances are slightly larger than the intervals between Ti5c ions yet significantly shorter than the C2H2 dimers in the gas phase. We propose that such clustered C2H2 may serve as potential precursors for the polymerization reactions on metal oxide surfaces.

The main aim of present study is to evaluate the effect of miR‐30b on the function of human proximal tubular epithelial cell line HK‐2 cells. For this purpose, miRNA was loaded in an ionically cross‐linked polysaccharide nanoparticle. The authors have demonstrated the influence of miR‐30b mimic and inhibitor in HK‐2 cell killing effect. Lipopolysaccharide (LPS) significantly increased the level of inflammatory cytokines of TNF‐α, IL‐1β and level was further increased with the treatment of PAg‐miR mimic consistent with the cell viability assay. Interestingly, PAg‐miR inhibitor significantly downregulated the expression of inflammatory cytokines and thereby reduced the inflammation in the body. Western blot analysis showed that LPS induced severe apoptosis of HK‐2 cells and the apoptosis was further promoted by the PAg‐miR (mimic). In contrast, PAg‐miR (inhibitor) alleviated the apoptosis of HK‐2 cells as indicated in the significantly reduced levels of Bax and c‐Caspase‐3 proteins. Overall, miR‐30b promoted LPS‐induced HK‐2 cell inflammatory injury by inducing the apoptosis and by releasing inflammatory cytokines, as well as by impairing autophagy process.

The adsorption and organization state of methanol on the ZnO surface is of importance for understanding the mechanism of the related (photo)catalytic reactions. In this work, by using high-resoluti...

A highly ordered copper(i) oxide film grown on a Pt(111) substrate exhibits extremely high reactivity to CO molecules. Systematic scanning tunneling microscopy experiments in combination with density-functional theory calculations demonstrate that the reaction occurs at the peripheries of the Cu2O islands where low-coordinated oxygen atoms are located.

The interface of graphene (G) and oxide can significantly influence the properties and/or applications of the binary system. However, it is usually beyond controllability during the conventional physical intermixing and/or solvothermal preparations. In this article, by directly growing nanocrystalline graphene films on the ZnO nanocrystals through a medium-temperature chemical vapor deposition method utilizing C2H2 as the carbon source, we successfully achieved a G/ZnO binary structure with a uniform and contamination-free G/oxide interface. The fabricated G/ZnO powders not only demonstrated a clear charge transfer between graphene and ZnO that leads to photoluminescence quenching, but also manifested an enhanced activity in the photocatalytic degradation of methylene blue when the graphene thickness is optimized. This work has demonstrated the essential significance of the interface control for the functionality of the graphene/semiconductor binary systems.

To achieve a best promotion effect of photocatalytic activity, an optimized interface between graphene and TiO2 is highly desirable, which is, however, difficult to realize via conventional preparation of the graphene/oxide composites. To this end, we here develop a novel strategy to directly grow graphene on the anatase-TiO2 (a-TiO2) nanosheet via an ambient pressure chemical vapor deposition (AP-CVD) method using acetylene as the precursor. Such a recipe successfully avoids the intercalating contaminations, meantime ensures the contact uniformity of graphene over a-TiO2 (G/a-TiO2). The ultrafast transient absorption spectroscopy clearly reveals the efficient charge transfer from TiO2 to graphene in assisting the separation of photoinduced electron–hole pairs. Moreover, the measurements of photocurrent and the photocatalytic degradation of methyl orange turn out that the composite with double layer graphene shows the best performance, which can possibly result from the competition of interlayer interacti...

The doping effect of Cu on the self-assembly film of melamine on an Au(111) surface has been investigated with scanning tunneling microscopy (STM). The evaporated Cu adatoms occupy the positions underneath the amino groups and change the hydrogen bonding pattern between the melamine molecules. Accordingly, the self-assembly structure has changed stepwise from a well-defined honeycomb into a track-like and then a triangular structure depending on the amount of Cu adatoms. The interaction between Cu adatom and melamine is moderate thus the Cu adatoms can be released upon mild heating to around 100 °C. These findings are different from previous observations of either the coordination assembly or the physically trapped metal adatoms.

The adsorption of the energetic molecule methyl nitrate (CH3ONO2) on α-Al2O3(0001) and γ-Al2O3(110) surfaces was investigated using first-principles calculations based on density functional theory and the generalized gradient approximation. We found that CH3ONO2 approaches the two surfaces by either the oxygen connected with carbon atom or an oxygen atom of the nitro group; however, the former interaction is more stable. If CH3ONO2 approaches the surface through the oxygen atom of the nitro group, the adsorption is non-dissociative; while it is nearly dissociative if CH3ONO2 adsorbs on the surface via the oxygen connected with carbon atom and a surface tri-coordinated Al atom. Moreover, the dissociation trend on the γ-Al2O3(110) surface is more pronounced. In addition, the adsorption of CH3ONO2 on the γ-Al2O3(110) surface is more favorable. Finally, although strong interactions exist between CH3ONO2 and the surfaces, the structures of the alumina films are not affected by the adsorption of CH3ONO2.

Supported metal films represent a model binary metallic system wherein the surface properties can be finely tuned with the composition/thickness of the film. Thus, it has raised increasing research interests from various aspects. In this work, the adsorption and assembly behavior of melamine on the Cu films grown on the (22 × √3) reconstructed Au(111) substrate were investigated as a function of Cu thickness. The atomically resolved scanning tunneling microscopy (STM) images in combination with density functional theory (DFT) calculations reveal that the ultrathin submonolayer copper film forms a pseudomorphic (1 × 1) lattice by agglomerating at the subsurface, while the true Cu adlayers start to appear on the three-layer thick films and hold the bulk Cu(111) lattice. Correspondingly, the adsorption and assembly of the melamine molecules significantly differ from those on pure metals, experiencing a gradual transformation from physisorption to chemisorption assemblies with the Cu film thickening. These fi...

The Tougu Xiaotong capsule (TXC) is a traditional herbal compound used to treat osteoarthritis (OA) in China. We performed fingerprint analysis with HPLC for the quality control of TXC. Its composition was identified by the comparison of the spectrogram and chromatographic peak of retention time with a reference substance. TXC was found to contain paeoniflorin, isofraxidin, ferulic acid, and rosmarinic acid. The chondrocytes were identified by immunohistochemical staining using collagen II. Chondrocytes that were positive for collagen II were stained brown in the cytoplasm. The toll-like receptor 4 (TLR4) was expressed on the chondrocyte membrane, which was observed using immunofluorescence microscopy. The nuclei were stained blue by 4′,6-diamidino-2-phenylindole (DAPI) and TLR4 was stained green. These were observed using laser scanning confocal microscopy. The successful establishment of LPS-exposed chondrocytes was confirmed using enzyme-linked immunosorbent assay (ELISA). Lipopolysaccharide (LPS) administration significantly reduced the levels of interleukin-1β (IL-1β) and tumor necrosis factor-α (TNF-α), and a maximum effect was observed at 8 h. We believe that these methods will be useful in future investigations of OA. This data article is related to the research article “Tougu Xiaotong capsules may inhibit p38 MAPK pathway-mediated inflammation: In vivo and in vitro verification” [1].

Dietary restriction (DR) can delay senescence, prolong lifespan of mammals and improve their learning-memory activity. The purpose of the study was to explore the effects of DR on hypolipidemic action and liver function of mice with hyperlipidemia. To investigate these effects, hyperlipidemia mouse models were established with high-fat diet (HFD) (34% of energy), then randomly divided into HFD group, DR30% group and DR50% group. Mice in DR30% and DR50% group were respectively supplied with HFD as much as about 70% and 50% of the consumption of HFD in the mice of HFD group. Rats in control group were fed routinely. After DR for 5 weeks, the average body weight, liver weight, liver index, serum lipids and glucose levels in both DR groups decreased significantly as compared with the HFD group (P

Atomic insights into the interaction of CO2 with the mixed-terminated ZnO(1010) surface were achieved in detail by low-temperature scanning tunneling microscopy (LT-STM) together with density functional theory (DFT) calculations. The binding site and adsorption geometry were directly imaged by LT-STM, revealing that the CO2 molecules are chemisorbed and turned into surface carbonate species. The strong interaction of CO2 with the ZnO(1010) surface in turn activates the surface, i.e., reconstructs the local surface such that facilitates further CO2 bindings, leading to the formation of a one-dimensional assembly structure which grows along the [0001] direction. DFT simulations indicated that the superior agglomeration energies along ⟨0001⟩ directions as well as the CO2-induced surface reconstruction are responsible for the directional growth of the surface carbonate chains.

The uniform and seamless interface between graphene and semiconductors, that is, without adsorbates or contamination in between, is of importance for optimizing the electronic and catalytic performances of the combined system. In this work, we try to synthesize graphene directly over atomically flat TiO2 single-crystal surfaces using chemical vapor deposition (CVD) with acetylene as the carbon source. The facile synthetic conditions facilitate the formation of ultrathin polycrystalline graphene films with nanosize domains, while reasonably maintaining the terrace-and-step morphologies of the TiO2 surfaces. The established recipe can thus lead to the construction of a contamination-free interface between graphene and reducible oxides and also provide a well-defined platform for further investigations into the physicochemical properties of the graphene–oxide complex system from an atomic/molecular level.

We systematically investigated the photocatalytic reaction of methanol on the TiO2 (110)-(1 × 1) surface under irradiation with ultraviolet (UV) light performed at various conditions, using scanning tunneling microscopy (STM) jointed with temperature-programmed desorption (TPD) techniques. Our STM and TPD results show that the photocatalytic reaction is indeed initiated from the molecular methanol at the 5-fold coordinated Ti sites, as commonly ascribed to the methanol oxidation by the photogenerated holes, reflecting the highly photoactive nature of methanol. The formaldehyde yield from the TPD results is much smaller by a factor of 2/3 than the amount of dissociated methanol from the STM results at 80 K. This observation can be assigned to the reverse reaction during the TPD measurement, and may explain the lower yield of formaldehyde using molecular methanol than using methoxy. From the fractal-like reaction kinetics of methanol, we can associate the coverage-dependence of the spectral dimensions with ...

Herein, a simple and green method was developed for the construction of water soluble fluorescent gold nanoclusters (Au NCs) with the assistance of l -carnosine as both a protecting ligand and a weak reducing agent. The as-prepared Au NCs, with the smaller size (2.31 nm) and longer fluorescence lifetime (7.48 ns), exhibited bright blue photoluminescence under UV light (365 nm) with a quantum yield of 3.4%, excellent stability, and low toxicity for cancer HeLa cell imaging.

Herein we report the synthesis of a novel hexabenzocoronene-containing cycloparaphenylene carbon nanoring, cyclo[12]-paraphenylene[2]-2,11-hexabenzocoronenylene, by metal-mediated cross-coupling reactions. The nanoring was accomplished by rationally designed palladium-catalyzed coupling of diborylhexabenzocoronene and L-shaped cyclohexane units, followed by nickel-mediated C-Br/C-Br coupling and the aromatization of cyclohexane moieties. The structure was confirmed by NMR and HR-MS. Especially, the cycloparaphenylene structure is firstly observed by STM. The photophysical properties were studied using UV-Vis spectroscopy, photoluminescence (PL) spectroscopy, and theoretical calculations.

Molecular self-assembly films are expected to tailor the surface process by the periodic nanostructures and add-on functional groups. In this work, a molecular network of melamine with featured pores of subnanometer size is prepared on the Au(111) surface, and is found to be able to trap the gold adatoms and concomitant single vacancies generated under the impingement of CO molecules at room temperature. DFT calculations suggest that the strong CO-Au adatom interaction as well as the high adhesion of the Au adatom inside the melamine pore could well be the driving force behind such process. This study not only sheds light onto the interactions between gasses and the metal surface that is covered by molecular self-assembly films, but also provides a novel route to manipulate the monoatomic surface species which is of catalytic interest.

In-feed Medication has been used for a long time to prevent coccidiosis, a worldwide protozoal disease in rabbits. Florfenicol (FFC) has been widely used in veterinary clinics for bacterial diseases treatment. Therefore, the use of combinations of coccidiostats with FFC in rabbits is common. In the present study, we aimed to evaluate the effect of three coccidiostats, sulfaquinoxaline (SUL), robenidine (ROB), and toltrazuril (TOL), as feed additives on the pharmacokinetic profile of FFC in rabbits. The disposition kinetics of FFC in rabbits were investigated after a single intravenous injection (25 mg/kg) in rabbits fed anticoccidial-free diets or feeds containing SUL (250 ppm), ROB (66 ppm), or TOL (2 ppm), respectively, for 20 days. Plasma FFC concentrations were determined by the high performance liquid chromatography (HPLC) method. The pharmacokinetic parameters of FFC were analyzed using a non-compartmental analysis based on the statistical moment theory. The results demonstrated that ROB feeding resulted in an obvious decrease in plasma FFC level as compared with anticoccidial-free feeding. The terminal elimination half-life (t1/2z), area under the concentration-time curve (AUC), area under the first moment curve (AUMC), and mean residence time (MRT) significantly decreased, whereas the elimination rate constant (λz) and total body clearance (CLz) obviously increased in rabbits pretreated with ROB. However, we did not find that SUL or TOL feeding had any effect on the pharmacokinetic profile of FFC. Our findings suggested that more attention should be paid to the use of FFC in rabbits supplemented with ROB.

In this work, uniform oxygen and sulfur co-doped graphitic carbon nitride quantum dots (OS-GCNQDs) have been prepared by thermal treatment of citric acid and thiourea. The as-obtained OS-GCNQDs show strong blue photoluminescence (PL) with a relatively high quantum yield of 14.5%. Furthermore, OS-GCNQDs exhibit stable and specific concentration-dependent PL intensities in the presence of mercury(II) ions in the range of 0.001–20.0 μM, with a detection limit of 0.37 nM (3S/N). More importantly, OS-GCNQDs were explored for cell imaging with satisfactory biocompatibility, and so are a potential fluorescent probe in biosensing and bioimaging applications.

Introduction The aim of this study was to compare the efficacy and toxicity of dicycloplatin plus paclitaxel with those of carboplatin plus paclitaxel as first-line treatment for patients with advanced non-small-cell lung cancer (NSCLC). Material and methods In this study, 240 NSCLC patients with stage IIIB (with pleural effusion) and stage IV disease were randomly assigned (1: 1) to receive dicycloplatin 450 mg/m(2) or carboplatin AUC = 5, in combination with paclitaxel 175 mg/m(2) (D + P or C + P) every 3 weeks for up to 4 to 6 cycles. The primary endpoint was response rate. Secondary endpoints included progression-free survival (PFS), overall survival (OS) and adverse events. Results The response rates for the D + P and C + P arm were 36.44% and 30.51%, respectively (p = 0.33). The median PFS was 5.6 months in the D + P arm and 4.7 months in the C + P arm (p = 0.31). The median OS was 14.9 months for D + P and 12.9 months for C + P (p = 0.37). Adverse events in the two arms were well balanced. The most common grade 3/4 adverse event was hematologic toxicity. Conclusions Patients treated with D + P had similar response and survival rates to those treated with C + P, and toxicities of both treatments were generally tolerable.

Objective To establish a model of retinal vein occlusion (RVO) in rats and to study the effect of puerarin on ischemic retinal disease and the corresponding mechanism. Methods RVO was induced in 10 adult male Sprague-Dawley (SD) rats by laser photothrombosis. Retinal blood flow was examined before and after 1 h of the operation, and model rats with the retinal vein blood flow decreasing by 50% compared to the basic value were chosen and then puerarins (20, 40, and 80 mg/kg) were given. The levels of vascular endothelial growth factor (VEGF), interleukin-1β (IL-1β), and nitric oxide (NO) were analyzed. In addition, the histopathology of RVO-eyes was performed. Results RVO-eyes displayed the signs of retinal damage and ischemia on Doppler Flowmeter and histopathology. Puerarin (20, 40, and 80 mg/kg) increased blood flow by 9.3% (P Conclusion A rat model of laser photochemical-induced RVO is established and a decrease in the retinal blood flow and histological damage is detected. The puerarin has therapeutic benefit in the rat model of RVO, through the pathway of neovascularization, anti-inflammation, and increase of NO.

Mating disruption and mass trapping of Ostrinia furnacalis (Genuee), often called the Asian corn borer, were incorporated with insecticides to reduce pesticide use. Pesticides alone are often ineffective owing to problems in timing applications before the larvae enter the protection of corn stalks. In addition, overuse of insecticides has caused environmental contamination and concerns about consumer health. In 2010, 15 insecticides were compared with mating disruption or mass trapping at various dispenser (disp.) densities for reducing egg masses, trap captures, and ear damage. Mass trapping with 30 and 40 disp./ha, mating disruption with 300 disp./ha, or endosulfan, chlorpyrifos, and monosultap (0.55, 0.35, and 0.55 kg/ha, respectively) gave ≍50% ear protection. In 2011, an insecticide alone, no treatments, pheromone alone, and pheromone + insecticide were examined. The same insecticides in combination with mating disruption or mass trapping at ≧200 or≧20 disp./ha gave >90% ear protection even when chemical applications were reduced to 1 from 3, and the rates were reduced 50-75%. Pheromone dispensers contained >50% of their initial load 30 d after exposure.

Two-dimensional self-assemblies of four partially fluorinated molecules, 1,4-bis(2,6-difluoropyridin-4-yl)benzene, 4,4'-bis(2,6-difluoropyridin-4-yl)-1,1'-biphenyl, 4,4'-bis(2,6-difluoropyridin-4-yl)-1,1':4',1″-terphenyl and 4,4'-bis(2,6-difluoropyridin-3-yl)-1,1'-biphenyl, involving weak intermolecular C. H⋯F and C. H⋯N hydrogen bonds were systematically investigated on Au(111) with low-temperature scanning tunneling microscopy. The inter-molecular connecting modes and binding sites were closely related to the backbones of the building blocks, . i.e., the molecule length determines its binding sites with neighboring molecules in the assemblies while the attaching positions of the N and F atoms dictate its approaching and docking angles. The experimental results demonstrate that multiple weak hydrogen bonds such as C. H⋯F and C. H⋯N can be efficiently applied to tune the molecular orientations and the self-assembly structures accordingly.

The nucleation and growth behavior of lithium on a CaO/Mo(001) thin film has been investigated by means of scanning tunneling microscopy and spectroscopy. The Li follows two different growth regimes on the surface. Whereas extended 2D islands develop on top of the defect-free CaO terraces, small 3D deposits decorate a network of domain boundaries that is present in the oxide film. The 2D islands have metallic character, as deduced from a standing wave pattern observed on their surface at low-bias. In contrast, a cationic nature is proposed for the defect-bound 30 species as a result of an electron-transfer from the Li 2s valence orbital into trap states localized in the CaO line defects. Tunneling spectroscopy reveals an unoccupied gap state below the CaO conduction band that originates from Li-O hybridization across the metal-oxide interface. With increasing diameter of the Li islands, this state shifts toward the Fermi level, reflecting the decreasing workfunction at higher Li coverage.

The ability of Mo (Cr) impurities in a CaO (MgO) matrix to act as charge donors to adsorbed gold has been investigated by means of scanning tunneling microscopy and density functional theory. Whereas CaO(Mo) features a robust donor characteristic, as deduced from a charge-transfer-driven crossover in the Au particles' geometry in the presence of dopants, MgO(Cr) is electrically inactive. The superior performance of the CaO(Mo) system is explained by the ability of the Mo ions to evolve from a +2 oxidation state in ideal CaO to a +5 state by transferring up to three electrons to the Au adislands. Cr ions in MgO, on the other hand, are stable only in the +2 and +3 charge states and can provide a single electron at best. Since this electron is likely to be captured by cationic vacancies or morphological defects in the real oxide, no charge transfer to Au particles takes place in this case. On the basis of our findings, we have developed general rules on how to optimize the electron donor characteristics of doped oxide materials.

Crystalline calcium-oxide films of various thicknesses have been grown on a Mo(001) support. The growth behavior and resulting film morphology have been characterized with low-energy electron diffraction, Auger spectroscopy, and scanning tunneling microscopy. At low film thickness, a considerable interdiffusion of Mo ions from the support into the ad-layer is revealed, giving rise to the development of a sharp (2 × 2) superstructure with respect to the Mo(001). The Ca/Mo mixed oxide has a similar lattice parameter as the metal substrate and therefore grows pseudomorphically with a very low defect concentration. At 4−5 ML thickness, the supply of Mo from the support is interrupted and pristine CaO patches start to grow on the surface. The reemerging lattice mismatch drives the system into the Stranski-Krastanov mode, as reflected by the formation of three-dimensional oxide islands. Above 15 ML nominal thickness, the islands merge into a closed film with high surface quality and low defect concentration. Th...

Although vinyl alcohol(CH2=CHOH)molecule was found to be an important intermediate in the combustion flames of hydrocarbon (Taatjes et al. in Science 308:1887, 2005), the removal mechanism of vinyl alcohol has not been established yet. The removal mechanism is critical to characterize the kinetics behavior of hydrocarbon in combustion chemistry and to develop the chemical models of hydrocarbon oxidation. In this work, the potential energy surface for the unimolecular decomposition of syn-CH2=CHOH reaction has been first studied by ab initio. The kinetics and product branching ratios for the decomposition reaction are evaluated by Variflex code in the temperature range of 500–3,000 K at 0.1, 1.0, and 100.0 atmosphere pressure. The results show that the formation of CH3 + CHO via the CH3CHO intermediate is dominant in the decomposition reaction and its branching ratios at 0.1, 1.0, and 100.0 atm are more than 99.90, 99.30, and 89.20%, respectively, through the whole temperature range investigated.

Methanol adsorption on the stoichiometric and slightly reduced ZnO(1010) surfaces has been studied by scanning tunneling microscopy (STM). On the stoichiometric surface it was found that adsorbed methanol formed two types of ordered structures by dissociative adsorption in different modes, one of which was a dominant two-dimensional island structure residing on surface zinc atom rows, while the other was a linear chain structure residing between two surface zinc rows. In addition, a mobile phase of molecularly adsorbed methanol was deduced occupying the areas aside the ordered domains and keeping in equilibrium with the island structure. In contrast to the stoichiometric surface, on the slightly reduced surface, only the linear chain structure was observed as an ordered phase, accompanied by an unusual type of line defects. The STM observations indicated that the drastic change of surface properties occurred on the whole surface not at the specific sites such as point vacancies.

Self-assembly of trimesic acid (TMA) displayed remarkable abundance over its full coverage range on gold under ultrahigh vacuum conditions. Experiments showed that previously well-reported “chicken wire” and “flower” structures were actually two special cases within its full coverage. All observed assembling structures formed hexagonal porous networks that could be well-described by a unified model in which the TMA molecules inside the half unit cells (equilateral triangles) were bound via trimeric hydrogen bonds and all half unit cells were connected to each other via dimeric hydrogen bonds. These porous networks possessed pores of 1.1 ± 0.1 nm in diameter, and the interpore distance was tunable from 1.6 nm on at a step size of ∼0.93 nm. Energetics analysis unveiled that the assembling structures less than one molecular layer was optimally driven by maximization of the dimeric hydrogen bonds.

Formation of partly dissociated water chains is observed on CaO(001) films upon water exposure at 300 K. While morphology and orientation of the 1D assemblies are revealed from scanning tunneling microscopy, their atomic structure is identified with infrared absorption spectroscopy combined with density functional theory calculations. The latter exploit an ab initio genetic algorithm linked to atomistic thermodynamics to determine low-energy H2O configurations on the oxide surface. The development of 1D structures on the C4v symmetric CaO(001) is triggered by symmetry-broken water tetramers and a favorable balance between adsorbate-adsorbate versus adsorbate-surface interactions at the constraint of the CaO lattice parameter.

Monomolecular-layer perovskite Ba 5 Ta 4 O 15 nanosheets with hexagonal structure have been synthesized by a hydrothermal method. The thickness of the nanosheets is about 1.1 nm, which corresponds to a monolayer of Ba 5 Ta 4 O 15 molecules, with the lateral size ranging from 50 to 200 nm. The optimal conditions for the formation of the nanosheets are maintaining the reactants above 270°C for 24 h. A dissolution-recrystallization mechanism is suggested based on observations of the factors that influence nanosheet formation, such as reaction time, temperature, and basicity. Formation of Ba 5 Ta 4 O 15 nanosheets takes precedence over other nanostructures under high concentrations of OH - because the hindering effect of OH - ions on the c-axis growth is strong. Thus, the extended growth rate of polyhedrons on one monolayer is much faster than the superposition rate of the monolayer, and the crystal grows more easily along the a- and b-planes. The Ba 5 Ta 4 O 15 nanosheets show a high photocatalytic activity in the degradation of Rhodamine B and gaseous formaldehyde. The layered perovskite probably affects the photocatalytic activity by promoting the charge separation and delocalization of photogenerated electrons and holes.

3,8-Bis-hexadecyloxy-benzo[c]cinnoline (BBC16) self-assembled into two structures at highly oriented pyrolytic graphite (HOPG) surface: one was formed by molecules with a V-like configuration (C2v symmetry) and the other by molecules with a Z-like configuration (C(s) symmetry). The self-assembled structures could be tweaked by the solvents used. In the self-assembled monolayers (SAMs) on HOPG, the BBC16 molecule adopted the V-like configuration in polar solvents and the Z-like configuration in nonpolar solvents. Moreover, the solvent viscosity, solvent dissolvability of BBC16, and substrate temperature also played some roles in tuning the two-dimensional self-assembled structures.

Using scanning tunneling microscopy, we have investigated how the doping of CaO thin films affects the growth behavior of gold. Whereas 3D deposits develop on pristine films, 2D islands form after inserting 4% of Mo into the CaO lattice. Adding small amounts of Li to the Mo-doped CaO reinstalls the initial 3D growth regime. We assign this morphology crossover to charge transfer processes between the dopants and the ad-metal. Whereas Mo acts as an electron donor and provides excess charges to be transferred into the gold, Li creates electron traps in the oxide lattice that interrupt the charge flow toward the metal. The different Au charge states in the presence of the dopants are derived from different growth morphologies with anionic gold favoring a 2D mode due to an enhanced interface adhesion. Our work demonstrates how oxide doping can be exploited to tailor the equilibrium geometry of ad-particles on supported metal catalysts.

Summary The phytohormone indole-3-acetic acid (IAA) plays a vital role in plant growth and development as a regulator of numerous biological processes. Its biosynthetic pathways have been studied for decades. Recent genetic and in vitro labeling evidence indicates that IAA in Arabidopsis thaliana and other plants is primarily synthesized from a precursor that is an intermediate in the tryptophan (Trp) biosynthetic pathway. To determine which intermediate(s) acts as the possible branchpoint for the Trp-independent IAA biosynthesis in plants, we took an in vivo approach by generating antisense indole-3-glycerol phosphate synthase (IGS) RNA transgenic plants and using available Arabidopsis Trp biosynthetic pathway mutants trp2-1 and trp3-1. Antisense transgenic plants display some auxin deficient-like phenotypes including small rosettes and reduced fertility. Protein gel blot analysis indicated that IGS expression was greatly reduced in the antisense lines. Quantitative analyses of IAA and Trp content in antisense IGS transgenic plants and Trp biosynthetic mutants revealed striking differences. Compared with wild-type plants, the Trp content in all the transgenic and mutant plants decreased significantly. However, total IAA levels were significantly decreased in antisense IGS transgenic plants, but remarkably increased in trp3-1 and trp2-1 plants. These results suggest that indole-3-glycerol phosphate (IGP) in the Arabidopsis Trp biosynthetic pathway serves as a branchpoint compound in the Trp-independent IAA de novo biosynthetic pathway.

Doping is a versatile yet little examined approach to tailor the physical and chemical properties of oxide thin films. By means of scanning tunneling microscopy (STM), we demonstrate how tiny amounts of Mo embedded in a CaO matrix change the growth behavior of gold. Whereas 3D deposits are formed on the pristine oxide surface, strictly 2D growth prevails on the doped material. The crossover in particle shape is driven by charge-transfer processes from the Mo dopants into the Au islands, as elucidated with density-functional theory (DFT) calculations.

By means of scanning tunneling microscopy, Auger spectroscopy, and density-functional theory, we have identified a different strain-relaxation mechanism taking place in ultrathin CaO films grown on Mo(001). Whereas CaO films are amorphous at low growth temperature due to the substantial lattice mismatch with the support, a crystalline phase develops upon annealing to 1000 K. This phase is characterized by a sharp (2 \ifmmode\times\else\texttimes\fi{} 2) pattern in low-energy electron diffraction and displays wide, atomically flat terraces in scanning tunneling microscopy images. The phase transition is initiated by the diffusion of Mo from the support into the film, where it replaces 25% of the Ca ions. The resulting rocksalt-type Ca${}_{3}$MoO${}_{4}$ structure has a negligible lattice mismatch with the Mo(001), enabling the growth of extended, defect-free oxide patches. The oxidation of Mo atoms from the support provides the thermodynamic stimulus for the phase transition. For MgO films grown on the same Mo(001) surface, no relevant intermixing is revealed at the interface, most likely because of the smaller lattice mismatch between both systems.

Thymic epithelial cells (TECs) constitute a major component of the thymic stroma which provides a microenvironment critical for developing thymocytes. We have previously demonstrated that doxycycline (Dox), a tetracycline derivative, enhances the proliferation of the mouse thymic epithelial cell line 1 (MTEC1) via MAPK/ERK signal pathway. Herein we provide evidence that Dox also has profound impact on the cytokine production by MTEC1. Specifically, the expression of IL-6 and GM-CSF, both at mRNA and protein levels, was found to be increased in a time- and dose-dependent manner with the addition of Dox. Western blotting analysis revealed that treatment with Dox-induced phosphorylation of the p65 subunit of NF-κB and ERK. Notably, Dox-induced up-regulation of IL-6 and GM-CSF was largely abolished after pretreatment of MTEC1 with either NF-κB inhibitor BAY11-7082 or MEK1/2 inhibitor U0126, supporting the involvement of the two pathways in the process. These findings warrant further investigation into the potential application of Dox in T-cell reconstitution in such situations as chemotherapy, radiotherapy, bone marrow transplantation and HIV infection.

Self-assembled structures of alkoxylated benzo[c]cinnoline derivatives prepared on highly oriented pyrolytic graphite at room temperature from their solutions in solvents such as 1-phenyloctane, toluene, and 1-octanol were studied by scanning tunneling microscopy. The alkoxy chain length markedly affected the molecular conformations in 2-dimensional assemblies of these derivatives. Long-chain derivatives adopted the trans conformations more often than cis, whereas short-chain derivatives took exclusively the cis conformations in the self-assembled monolayers (SAMs). For the derivatives of intermediate chain lengths, polymorphism existed, with four molecular conformations identified experimentally. Experimental evidence substantiated the formation of chiral SAM structures at the surface, which can be explained by the conformations of the molecules. The chirality was also affected by the chain length of the molecules. A simple method analyzing the angles between different domains in the SAMs was used to identify the molecular conformations and to predict their relative structures.