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Cr-doped BaSnO3 (BaSn1-xCrxO3, BSCO-x, x = 0–0.15) thin films with nanoporous structure were deposited on fluorine-doped tin oxide substrates via a colloidal solution route. The BSCO-x films exhibited single cubic perovskite phase and nanoporous feature, with the typical specific surface area of 18.98 m2/g and pore size of 10.75 nm (BSCO-0.15). The lowest band gap of 2.68 eV and a high transparency (above 70% in 500–800 nm) were realized in BSCO-0.15 film. This work paves a way toward perovskites with tunable band gap and nanoporous structures for varied photo and photoelectric devices.

Co doped SrSnO3 films (SrSn1-xCoxO3 ( 0 ≤ x ≤ 1 . 0 ), i.e., SSCO) was grown on MgO single crystal substrates by pulsed laser deposition method. Effects of the Co doping content on the crystallinity , microstructure, optical and magnetic properties were examined. For all the films the epitaxial growth along (002) plane was realized, and the lattice constant dropped from 4.065 A to 3.854 A with the ‘x’ value changing from 0 to 1.0. The Co doping promoted the growth of grains and the RMS roughness of the film increased from 3.17 nm to 9.44 nm. With the increase of the Co doping level, the optical transmittance decreased from 95% to 28% at 500 nm, and the band gap varied from 4.51 eV to 3.16 eV. All the films exhibited the room temperature ferromagnetism , and the highest saturated magnetization of 61 emu/cm 3 and the coercive force of 0.018 T were realized in the SSCO (x = 1.0) film.

The confined high-temperature reaction and/or phase changes occurred in the nanopores of SiO2 aerogel modified by various oxides is intriguing but receiving less attention. Here we report the distinctive phase conversion from amorphous SiO2 to cristobalite at high temperature in SiO2 aerogel induced by Ba/Sn oxides. We prepare Ba-Sn-SiO2 hybrid aerogel via a co-precursor sol–gel method, and the effects of SiO2 content (40–100%), sintering temperature (100–1000 °C) on the crystallinity and microstructure are examined. Results show that the introduction of Ba/Sn and the sintering temperature exert significant influences on the crystallinity, microstructure and pore structure of the hybrid system. In special, the cristobalite SiO2 is formed at higher Ba-Sn content (>33.3%) and higher sintering temperature (>800 °C), corresponding with the sharply decrease of the pore volume and surface area. The formation mechanism of cristobalite is explored, and a BaSnSi3O9-induced SiO2 epitaxial nucleation lattice matching mechanism is proposed. The work may induce the interests on the high-temperature synthesis of aerogel-based hybrid materials possessing particular physical/chemical functions, thus paving the way to advanced structural or functional materials/devices.

Amphiphilic aerogels based on the SiO2–chitosan composite system with strong purifying capacity to intractable emulsified wastewaters are presented. The hybrid aerogels are realized by integrating the hydrophilic chitosan into an organosilane modified SiO2 nanoframework via sol–gel and ambient drying processes. The uniform hybridization of SiO2 and chitosan nanoparticles (∼3–10 nm) at the nanoscale, small pore size ( 90% after 10 cycles). An interesting descending trend in the contact angle (from 114.6° to 90.5°) with the measuring time is observed, originating from the nanoporous and amphiphilic surface properties. Rapid (5 minutes) and effective treatment of a high concentration polyacrylic emulsion (chemical oxygen demand (COD): 1 138 000) or on-line machining emulsified wastewater (COD: 471 200) is demonstrated, exhibiting high absorption capacity (5 g g−1) and high purification efficiencies (98.4% and 96%), much better than those with activated carbon. In addition, the simultaneous removal of heavy metal ions (Pb2+ and Cu2+) from the machining emulsified wastewater is observed.

Co doped BaSnO3 films [BaSn1 − xCoxO3(0 ≤ x ≤ 0.50), i.e., BSCO] have been grown on MgO single-crystal substrates via pulsed laser deposition. Effects of the Co-doping level on the crystallinity, the microstructure, and optical properties of the BSCO films are investigated. All the BSCO films are of high crystallinity and grown epitaxially on MgO substrates. The lattice parameter of the (200) plane drops linearly with the increase of the ‘x’ value. The Co doping is found to increase the film roughness and the grain size, and a RMS roughness of 8.33 nm and grain size up to 100 nm are observed in the film with x = 0.50. The low Co-doping level (x = 0.05, 0.1) has slight anti-reflection effects on the incident visible light, and the Co-doping level higher than 0.2 reduces the optical transmittance significantly. The optical bandgap shows a first-rising then falling trend with the increase of the Co content, and the lowest bandgap of 1.94 eV is realized in the BSCO film with x = 0.50.

In this paper, we study lag synchronization between two coupled networks and apply two types of control schemes, including the open-plus-closed-loop (OPCL) and adaptive controls. We then design the corresponding control algorithms according to the OPCL and adaptive feedback schemes. With the designed controllers, we obtain two theorems on the lag synchronization based on Lyapunov stability theory and Barbalat's lemma. Finally we provide numerical examples to show the effectiveness of the obtained controllers and see that the adaptive control is stronger than the OPCL control when realizing the lag synchronization between two coupled networks with different coupling structures.

The metamaterial radiative cooling films based on nanoporous SiO2 microsphere-Poly-4-methyl -1-pentene (TPX) hybrid system were deposited on fluorine doped tin oxide (FTO) substrates via tape casting. Effects of the fabrication parameters, film thickness, SiO2/TPX volumetric ratio and microsphere size on the crystallinity, microstructure, optical transmittance and infrared emittance of the hybrid films were examined. Results show that the crystallinity of the TPX matrix is influenced by the deposition temperature, and the microstructure of the hybrid film is influenced by the film thickness, with the film of 50 μm thickness exhibiting porous microstructure on the surface. The optical transmittance in the visible-near infrared band decreases with the increase of the film thickness and the SiO2/TPX volumetric ratio, and with the decrease of the microsphere size. The absolute quantity of SiO2 microspheres in hybrid film determines the transmittance and the scattering effect. The emittance at 8–13 μm increases with the increase of the film thickness and the SiO2/TPX ratio and with the decrease of microsphere size. The film with 50 μm thickness, 5% SiO2/TPX ratio and 8 μm microspheres exhibits both high emittance (up to 0.91) and high selectivity in the atmospheric window. The cooling device integrating the optimal hybrid film and silver reflective layer demonstrates the lowest temperature in the diurnal test, about 20 °C lower than the black surface, 12 °C lower than the Ag-coated glass and 8 °C lower than the FTO sample. In the nocturnal test, the maximum 4.5 °C reduction relative to the ambient temperature is observed.

We report a simple strategy towards nanocrystalline photoanodes with structural hierarchies (hn-electrode) and simultaneously enhanced dye-loading capacity and electron conductivity. Totally built up by TiO 2 nanocrystallite (5–20 nm), the hn-electrode comprised two major parts: the nanocrystalline matrix, and the bi-functional TiO 2 mesostructure (BF-TiO 2 ). BF-TiO 2 was obtained from common sol–gel, ambient-drying and annealing processes, modified with very high H 2 O/Ti ratio (48.9:1) and hexamethylenetetramine additive. Two morphologies were found in BF-TiO 2 : high-surface-area mesoporous nanograin aggregates, and conductive nanosheets composed of both anatase TiO 2 and oxygen-deficient Ti 6 O 11 , corresponding to its two functions. The preferential capping of amino groups on high-energy facets of TiO 2 and the self-assembly process of nanograins along high-energy facets promoted the formation of nanosheets. Hn-electrodes with BF-TiO 2 level of 5–40 % were prepared, which exhibited the maximum improvement of 110% in the dye loading capacity, much lower recombination frequency (8.1 Hz vs. 31.5 Hz), and much longer electron lifetime than the disordered counterpart. The optimal hn-electrode (20% BF-TiO 2 , ~16 μm) with and without the scattering layer exhibited the conversion efficiency of 8.03% and 7.99%, ~29% higher than the control nanocrystalline electrode (6.24%). The work provides a versatile route towards functional-integrating hierarchical materials, and may find vast applications in relevant areas such as lithium batteries, supercapacitors and photocatalysts.

(Pb1-xLax)Ti1-x/4O3 (PLT) ferroelectric thin films with various La concentrations have been grown on LaNiO3/Si(100) substrates by a modified sol-gel technique. X-ray-diffraction analyses show that the PLT and LaNiO3 thin films are polycrystalline and entirely perovskite phase. The infrared optical properties of the PLT thin films have been investigated using infrared spectroscopic ellipsometry in the wavelength range of 2.5–12.5 μm. By fitting the measured ellipsometric parameter (cosΨ and cosΔ) data with a four-phase model (air/PLT/LaNiO3/Si), and a derived dispersion relation for the PLT thin films, the optical constants and thicknesses of the thin films have been determined. The refractive index of the PLT thin films decreases with increasing wavelength; however, by a Kramers–Kronig analysis the extinction coefficient increases with increasing wavelength. Moreover, the refractive index and extinction coefficient of the PLT thin films increase with increasing La concentration. This indicates that the infrared optical constants of the PLT thin films are a function of the La concentration. It is believed that the increase in the infrared optical constants of the PLT thin films with increasing La concentration is mainly due to the crystallinity and the electronic band structure of the PLT thin films.

Lead lanthanum zirconate titanate (PLZT) thin films with different La concentrations ( x ), whose composition is x /40/60, have been grown directly on Pt/Ti/SiO 2 /Si (100) substrates by a modified sol-gel method. X-ray diffraction analysis shows that the PLZT thin films are polycrystalline. The infrared optical properties of the PLZT thin films have been investigated using the infrared spectroscopic ellipsometry in the spectral range of 2.5–12.5 μm. By fitting the measured ellipsometric spectra ( Ψ and Δ ) with a three-phase model (air/PLZT/Pt), and a derived classical dispersion relation for the thin films, the optical constants and thicknesses of the thin films have been obtained. The refractive index of the PLZT thin films decreases with increasing La concentrations, however, the extinction coefficient increases with increasing La concentrations except for the PLZT(4/40/60) thin films. The values of the effective static charge calculated for the PLZT thin films, which state that PLZT belongs to a mixed ionic-covalent compound, decrease with increasing La concentrations. Moreover, the refractive index at the wavelength of 2.5 μm changes linearly with the effective static charge. The plot of the calculated infrared optical absorption versus wavelength for the Ni/PLZT/Pt multilayer structures with various La concentrations is given and indicates that the PLZT thin films are excellent candidates for ferroelectric infrared detectors and focal plane arrays.

In Escherichia coli, the phenylalanine-sensitive 3-deoxy-D-arabino-heptulosonate-7-phosphate synthase (DAHPS) AroG catalyzes the first committed step in the biosynthesis of aromatic compounds. To investigate the feedback inhibition site of AroG, mutated enzymes prepared with sequence-overlap extension PCR were expressed and purified. The enzymatic activity assay showed that the amino acid replacements at Phe144, Leu175, Leu179, Phe209, Trp215Ala and Val221 completely or partially relieved feedback inhibition of AroG addressed by the phenylalanine. Ile10Ala and Delta(1-15) desensitized feedback inhibition and caused a 70 approximately 90% loss of the specific catalytic activities. These results strongly suggest an involvement of the interior region and the N-terminus of the polypeptide chain of AroG in the formation of the feedback inhibition site of DAHPS.

Ag nanoparticles were prepared on the surface of multi-walled carbon nanotubes( MCNTs) by thermal evaporation deposition at room temperature. The morphology and microstructures of Ag/CNTs composites were characterized by SEM,XRD,TEM and HRTEM. The measurement results verify the nanocrystal shape of Ag nanoparticles on the MCNTs. Ag nanoparticles are distributed evenly on the MCNTs and the density of Ag nanoparticles reaches 10(11) cm(-2). Ag nanoparticles present round or elliptical patterns and the round particles have larger diameter than the elliptical ones. The MCNTs are deformed at where Ag nanoparticles grow, which should be attributed to the interaction between Ag nanoparticles and MCNTs during the evolution. The heterojuntion materials are formed by the deformed MCNTs and as-grown Ag nanoparticles. It is found that the heterojuntion materials share mutual connections and constitute a net structure because the chemical bonds between Ag nanoparticles and MCNTs have fixation on reciprocal chiasmata MCNTs. The as-prepared 0-1 dimensional materials have promising applications in sensors, catalysis and optoelectronic devices.

Electrochemical behavior of DNA at C 60 :γ-cyclodextrin (C 60 :γ-CD) and Nafion chemically modified electrodes in aqueous solution was investigated. It was found that C 60 :γ-CD is capable of mediating the electron transfer to DNA, showing two-way electrocatalytic activity toward DNA.

Cyclic voltammetry reveals that C60-γ-cyclodextrin and Nafion CME has a reversible electroreduction wave in an aqueous solution. The electrochemical behavior of hemin at the CME has been investigated.

The C60-γ-cyclodextrin and Nafion chemically modified electrode exhibits two redox waves by cyclic voltammetry. Such an electrode will effect reduction and oxidation of cytochrome c and be capable of mediating the electron transfer to cytochrome c.

The electrochemical behavior of films of C 60 - γ -cyclodextrin (1 : 2) and Nafion has been studied in an aqueous solution. A reversible surface-confined electroreduction wave and an irreversible electroreduction wave were detected by cyclic voltammetry. It is found that the chemically modified electrode has electrocatalytic activity to hemoglobin.

The electrochemical behavior of films of C60-γ-cyclodextrin (1:1) and Nafion has been studied in an aqueous solution. A reversible surface-confined one-electron-transfer electroreduction wave was detected by cyclic voltammetry. The CME displayed electrocatalytic activity to hemoglobin in a 0.10 M KCl solution.

The first electrodeposition in situ of C70-salt films in a mixed solvent on a microdisk electrode is reported. The deposition conditions of these films were optimized and then the electrochemical behaviors of these films were investigated, displaying three one-electron oxidation peaks with the characteristics of surface reactions. The electron-transfer coefficients (α) of the three surface reactions were also determined.

The electrochemical behavior of the water-soluble C60–γ-CD (1:1) inclusion complex has been studied on the hanging mercury drop electrode. A one-electron reversible adsorptive electroreduction and three irreversible adsorptive electroreductions were detected by cyclic voltammetry. The amount of C60–γ-CD adsorbed at saturation is 1.73 × 10−11 mol/cm2, the diffusion coefficient is 5.81 × 10−6 cm2/s, and the standard rate constant of the surface reaction ks are 0.888 s−1, 0.853 s−1 and 1.032 s−1, respectively.

The solubilities of fullerene C60 and C70 in toluene, o-xylene and carbon disulfide between the melting point and boiling point of the solvents, respectively, have been measured. The temperature dependent solubility of C60 displays anomalous behaviors. A solubility maximum of C60 around 0 °C for toluene and carbon sulfide and around 30 °C for o-xylene was observed. The temperature-dependent solubility of C70 behaves normally for all the three solvents studied.

In this paper, the formation in situ of an electrodeposited film of (TBA+)n(Cn−60) (n = 1 to 3) on a microelectrode and its voltammetric behavior have been studied. The method consists of electroreducing C60 in a mixed solvent of acetonitrile and xylene (1:6 v/v) and a supporting electrolyte of 0.08 M TBAPF6 at a potential sufficiently negative to generate C3−60 anion, followed by deposition of (TBA+)3(C3−60) on a microdisk electrode. Deposition conditions of the film and some of its characteristics were investigated. The standard surface electron-transfer rate constants k0 and electron-transfer coefficient α of the two stripping reactions were determined.

A simple and selective HPLC method for the determination of coronene in hydrocracked vacuum gas oils is described. The method is based on normal-phase HPLC separation on a column packed with 3,5-dinitroben-zamidopropyl (DNBAP)-silica gel and on-line detection of the eluate with a diode-array detector. The diluted oil samples were injected directly on to the DNBAP column with a mixture of light petroleum (b.p. 60–90°C) and o-xylene as eluent. The absolute detection limit was 7.9 ng when using UV detection at 305 nm, corresponding to a concentration detection limit of 4.0 μg/g in the original oil samples, if a 20-μl diluted sample with an oil concentration of 0.1 g/ml is injected. The relative standard deviation for ten replicate determinations was 2.8% at a coronene concentration of 7.02 μg/ml.

Electrochemical behavior of the water-soluble C60-γ-CD (1:2) inclusion complex has been studied on the hanging mercury drop electrode. A one-electron reversible adsorptive electro-reduction and three irreversible adsorptive electro-reductions were detected by cyclic voltammetry. The amount of C60-γ-CD adsorbed at saturation is 2.50 × 10−11 mol cm−2, the diffusion coefficient is 4.36 × 10−6cm2s−1 and the standard rate constant of the surface reaction ks are 0.745 s−1, 0.612 s−1 and 0.513s−1, respectively.

This paper reports on preconcentration and separation of trace Pd(II) and Pt(IV) with silica gel bonded by aminopropyl-benzoylazo-1-(2-pyridylazo)-2-naphthol (ABPN · SG). ABPN · SG is stable in solution between 6 mol/liter HCl and pH 9.0. The maximum adsorptive capacity of Pd(II) on ABPN · SG is 96 μmol/g. After preconcentration and separation using an ABPN · SG column, Pd(II) and Pt(IV) of ppb level in artificial water samples can be measured by spectrophotometry.

Some common solvents were roughly classified into four classes according to their decreasing solubility for fullerenes. Good solvents should be used in

DMAC using the staggered wakeup schedule can achieve both low latency and low energy consumption. However, the data gathering tree built by DMAC is fixed permanently. A fixed data gathering tree can't adapt to the variability in the environment of wireless sensor networks, and it needs to be reconstructed frequently to suit the current environment. For example, the interference is a factor that will change the environment because it changes node connectivity of wireless sensor networks. In this paper, we propose Robust-DMAC (RDMAC) which can dynamically construct the data gathering tree according to the changing environment. Because RDMAC separates the formation of the data gathering tree from the arrangement of the wakeup schedules, it can easily construct a new data gathering tree without adjusting nodes' schedules. From simulation results in variable environments affected by interference, it is shown that RDMAC performs closely with DMAC in effective energy consumption and has remarkable improvement in packet arrival ratio, network throughput, and packet delivery latency over DMAC.

tyrR gene encodes a global regulatory protein (TyrR), which plays an important role in the transcriptional regulation of eight transcription units (including tyrR gene itself) whose protein products catalyze key steps in aromatic amino acid biosynthesis and/or transport. The aroP gene encodes an integral membrane protein (AroP) that transports aromatic amino acids through the cell membrane. The transcription of aroP was reported to be repressed by TyrR. In this work, aroP(p) (aroP gene carrying its own promoter), aroP (aroP gene without promoter) and tyrR genes were amplified by PCR from genomic DNA of E. coli K12 and introduced into E. coli WT5. The expression of aroP and tyrR were detected and the activities of AroP and TyrR were determined. The introduction of either aroP(p) or aroP elevated the strain's transport activity by 1.40 or 1.46-fold respectively. Transformant carrying tyrR gene showed an ATPase activity 1.69-fold compared with the control. When the genes were linked in tandem and co-expressed in a plasmid, the relative AroP transport activity of the strain harboring aroP(p) -tyrR (0.95) was significantly lower than that of aroP-tyrR (1.31). The results indicated that TyrR might be able to reduce the expression of aroP gene by binding with the aroP promoter region in E.coli.

It is intriguing and challenging to utilize aerogels with a very high surface area to enhance the light-harvesting capacity of a photoanode. Here we demonstrate highly efficient aerogel-modified photoanodes by modifying both the aerogel's microstructure and the photoanode's functions. A low-cost sol–gel and ambient-drying route is developed to fabricate high-quality SiO2 and SiO2–TiO2 hybrid aerogels with tunable surface area (500–1170 m2 g−1) and packing density (0.03–0.27 g cm−3). Two series of hybrid photoanodes integrating SiO2–TiO2 aerogel microparticles and TiO2 nanocrystallites are designed, to overcome the intrinsic weakness of the mesoporous structure in the electron-transporting property. The aerogel-modified photoanodes yield significantly higher photocurrent densities than the TiO2 nanocrystallite photoanode due to their increased dye-loading capacity and the enhanced visible light scattering effect. A distinctive interaction enhancement of the cell efficiency between the dye-loading and the light-scattering effect induced by the aerogel microparticles is observed. At optimal conditions (aerogel: 0.202 g cm−3 packing density, 15 wt% incorporation), the primitive aerogel-modified photoanode exhibits a conversion efficiency of 7.57%, much higher than the pure TiO2 counterpart (3.67%). When optimized with TiCl4 treatment and a higher film thickness, it shows the highest efficiency of 9.41%, 16% higher than the TiCl4-treated TiO2 photoanode modified with a conventional scattering layer. The work affords a simple, powerful and versatile route towards highly efficient hybrid photoanodes utilizing mesoporous materials, and also shows great promise for extension to other applications such as supercapacitors or photocatalysis.

AIM: To study the effect of co-expression of ppsA, pckA, aroG, pheA and tyrB genes on the production of L-phenylalanine, and to construct a genetic engineering strain for L-phenylalanine. METHODS: ppsA and pckA genes were amplified from genomic DNA of E. coli by polymerase chain reaction, and then introduced into shuttle vectors between E coli and Brevibacterium flavum to generate constructs pJN2 and pJN5. pJN2 was generated by inserting ppsA and pckA genes into vector pCZ; whereas pJN5 was obtained by introducing ppsA and pckA genes into pCZ-GAB, which was originally constructed for co-expression of aroG, pheA and tyrB genes. The recombinant plasmids were then introduced into B. flavum by electroporation and the transformants were used for L-phenylalanine fermentation. RESULTS: Compared with the original B. flavum cells, all the transformants were showed to have increased five enzyme activities specifically, and have enhanced L-phenylalanine biosynthesis ability variably. pJN5 transformant was observed to have the highest elevation of L-phenylalanine production by a 3.4-fold. Co-expression of ppsA and pckA increased activity of DAHP synthetase significantly. CONCLUSION: Co-expression of ppsA and pckA genes in B. flavum could remarkably increase the expression of DAHP synthetase; Co-expression of ppsA, pckA, aroG, pheA and tyrB of E. coli in B. flavum was a feasible approach to construct a strain for phenylalanine production.