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Due to the advantages of narrow energy distribution of plasmonic hot-electrons in Ag and the high density of states in the TiO2 conduction band, an Ag/TiO2 composite is considered to be an ideal combination to construct a plasmonic hot-electron photodetector with high detectivity and a high response speed. In this work, we fabricate a porous Ag/TiO2-Schottky-diode based plasmonic hot-electron photodetector. This detector shows a high detectivity of 9.8 × 1010 cmHz1/2/W and a fast response speed, with a rise and fall time of 112 μs and 24 μs, respectively, under 450 nm light illumination at zero bias voltage. In addition, the height of the Ag/TiO2 Schottky barrier can be decreased by removing the chemisorbed oxygen from the surface of TiO2 with ultraviolet light illumination, and as a result, the responsivity of the Ag/TiO2 plasmonic hot-electron photodetector at 450 nm can increase from 3.4 mA/W to 7.4 mA/W.

This paper presents a systematic study of Raman spectra of nanocomposite photonic crystals produced using opal matrices or anodic aluminum oxide and filled with various inorganic compounds. We compare Raman spectra of the starting inorganic compounds (K2Cr2O7, CrO3, and KIO3) and nanocomposite photonic crystals whose pores are filled with the inorganic substances. Our results open up the possibility of producing high-performance sensors of inorganic substances introduced into the pores of photonic crystals, based on analysis of enhanced Raman scattering in a nanocomposite photonic crystal.

Wheat is the main food crop in China while at the same time, heavy metals pose a significant threat to crop growth and food security. Many studies indicate that rhizospheric microorganism play an important role in regulating crop development and stress resistance. In this study, the variation in wheat root-associated microbial communities under copper pollution was studied using high-throughput sequencing. The microbial community structure and diversity among different wheat rhizocompartments were compared after sequencing of microbial communities in the bulk soil, rhizosphere, and endosphere of wheat under copper pollution in combination with pot-based experiments. The results showed that the microbial diversity of the endosphere was significantly lower than in the rhizosphere and bulk soil(

The optical properties of a one-dimensional photonic crystal based on porous alumina with a crystal lattice constant of 460 nm were studied. The experimentally measured transmission spectrum of a one-dimensional photonic crystal film was compared with the theoretical spectrum in the spectral regions corresponding to the first, second, and third stop bands. The potential for using one-dimensional porous alumina photonic crystals as selective narrow-band filters and sensors was analyzed. Embedding a Raman-active medium into the voids of porous photonic crystal should provide an essential increase of spontaneous Raman scattering signal and low-threshold stimulated Raman scattering. The amount of substance needed for recording Raman spectra may be substantially decreased.

In this article, pure and tungsten-doped (W-doped) highly ordered two-dimensional (2D) vanadium dioxide (VO2) nanowire arrays were successfully prepared by a hydrothermal treatment, followed by a self-assembly progress and the in-situ high temperature treatment. The infrared photodetector devices based on monoclinic VO2 (VO2(M)) and W-doped VO2(M) nanowires were comparatively studied . It was found that the device based on W-doped VO2(M) nanowires exhibits a rapid infrared response and an enhanced photoelectric responsivity of 21.4 mA/W under the incident infrared light intensity of 280 mW/cm2, which is nearly two orders of magnitude superior to pure VO2(M) nanowire array. Our experimental results provided a direct and convenient path for design of future high-performance photodetector devices.

The angular dependences of the transmission of a one-dimensional photonic crystal based on porous anodic aluminum oxide are studied in the wavelength range of 320–1200 nm. The possibility of using porous one-dimensional photonic crystals based on aluminum oxide as selective narrowband optical filters and mirrors is studied.

Tb3+-doped TiO2 (TiO2:Tb3+) films are synthesized by a facile sol-gel method. The hot-electron current of Au/TiO2:Tb3+ Schottky diodes was enhanced by UV light decreasing the height of Schottky barrier. Compared with pure TiO2, doping Tb3+ can reduce the background current originating from the internal photoelectric effect in TiO2, and improve the on/off ratio. This is due to the energy and charge transfer mechanism from TiO2 to Tb3+. Photogenerated electrons in TiO2:Tb3+ films excited by UV light can be consumed by radiative electron transitions from the level 5D4 to the 7Fj (j=6, 5, 4, 3) for Tb3+. This is beneficial and effective to regulate the electronic state of optoelectronic materials.

Herein, we report an enhanced tunable broadband wavelength-selective lead sulfide (PbS) film detector integrated with Au-nanorod arrays that were obtained by using an ultrathin open-ended porous titanium dioxide membrane (UOP-TM) as a mask. The responsivity of the PbS films with periodic Au-nanorods exhibits a drastic enhancement by up to 125%–175% due to the enhancement of the localized electromagnetic fields around the gold nanorods. Notably, the location of the strongest enhancement peak of photocurrent shifted from 450 to 980 nm as the height of the Au-nanorods increased from 30 to 120 nm. In addition, the responsivity and detectivity of the hybrid PbS film modified with 90 nm Au-nanorod arrays under laser illumination of 980 nm are as high as 944 mA W−1 and 1.72 × 1010 cm Hz1/2 W−1, respectively. These excellent figures-of-merit of the tunable broadband plasma-enhanced PbS films could be a promising candidate in future wavelength-selective photodetector applications.

Infrared antireflection (AR) coatings as an important part of infrared components play an important role in the infrared system. Herein, high transmittance of infrared AR coatings were successfully prepared on TeO2 substrate by sol–gel method. Two kinds of sols, including SiO2-TiO2-PVA sol and SiO2-TiO2-PEG600 sol with optimized composition ratio, were designed to prepare AR coatings according to the theory calculation. The microstructures and optical properties were studied by scanning electron microscope and spectrophotometer, respectively. High transmittance of about 99.8% at 1550 nm and 99.6% at 2008 nm, respectively, was achieved in SiO2-TiO2-PVA film coated sample, and the transmittance of about 100% at 2330 nm and 2460 nm, respectively, was achieved in SiO2-TiO2-PEG600 film coated sample. Both AR films have very low roughness, which is conductive to reducing surface scattering. It is found that SiO2-TiO2-PEG600 film shows a more structural stability than SiO2-TiO2-PVA film during annealing. The durability of the films such as adhesion property, water resistance, high and low temperature resistance, and laser tolerance were examined systematically.

Designing and fabrication of the infrared antireflection coatings are quite important for the application of infrared optical elements. Herein, double-layer two wavelength infrared antireflective (AR) coating was prepared on CdSe substrate by sol-gel method, in which the bottom layer is porous TiO2 film and the top layer is SiO2 nanoparticle film containing a small amount of TiO2 (molar ratio of Si/Ti is 7.7). The reflectivity of the coated sample is about 2.1% at 2000 nm and 2.8% at 2500 nm, respectively, and the average reflectivity of the whole wide band from 1800 nm to 2600 nm is about 2.6%, which is about 27% lower than that of uncoated CdSe substrate. By adding reasonable additives and designing the film structure, the problem that thick infrared film is not resistant to high temperature annealing was solved. Moreover, the AR coating shows a super hydrophilicity, which can avoid the influence of water mist condensation on the transmittance. Importantly, this AR coating exhibits a good thermal shock resistance, and the reflection spectrum of the film did not change after ten thermal shock cycles at 400 °C, which meaning this film can be expected to meet the requirements of high temperature irradiation environment. This work provides important guidance for the preparation of infrared AR film with high thermal stability.

High-quality Sn2+-sensitized PbS films were deposited via a cost‐effective chemical route. The results demonstrate that the Sn2+-sensitized PbS thin films have better crystallinity and larger grain size. Photoelectric performance of Sn2+-sensitized PbS films has been improved greatly in the visible and near-infrared range. With Sn2+ sensibilization, photoresponsivity is more than 9 times higher, and detectivity is as high as ~1010 cm2 Hz1/2 W−1. Notably, the response speed of the Sn2+-sensitized PbS films reaches a magnitude of microseconds, which is over 105 times improvements compared with the pure PbS film devices. Additionally, high-frequency switching behavior at 4 kHz shows excellent stability. Based on the feasible method and excellent photoelectric performance of the devices, it has been demonstrated that Sn2+ sensibilization is of viability to improve the detection performance of commercial photodetectors.

In this paper, we fabricate ordered pore array (OPA) Ag film coated glass with the aid of polystyrene sphere (PS) array templates. This kind of OPA Ag coated glass has optical advantages of visible transparency, blue and near-infrared resistance. The average visible transmittance is 68%, including a transmission peak of 78% located at 570 nm, and low average transmittance of 48% in the blue light region that is not damaging to the eyes. The near-infrared light blocking rate is 67%, among which 40% light is reflected directly, indicating the reflection domination.

Xiamen Xiangan Subsea Tunnel is the first undersea tunnel constructed in China. It has become the major undersea pathway connecting Xiamen Island and Xiangan District since its operation in 2010. The total length is 6.05 km with the undersea length of 4.2 km. In an effort to onsite-monitor reinforcement corrosion in concrete structures, the commercially available CorroWatch multiprobe sensors and ERE-20 reference electrodes were pre-embedded in the selected locations and positions of supporting structures during the tunnel constructions. The real-time data have been collected annually by onsite measurements for 6 years. In this paper, the feasibility of the onsite corrosion monitoring system and suitability of the measured parameters including corrosion current, potential and temperature are discussed based on the preliminary results. The measured typical cyclic-type variations in corrosion current and temperature with monitoring time might be related to the seasonal changes during the annual routine measurements. The widely scattered corrosion potentials that are fluctuated complicatedly reflected localized differences in the vicinity of rebar and concrete. These findings, along with the progressively ongoing research, will provide valuable information in structural durability for service life prediction of reinforced concrete structures exposed to marine environments.

Uniform tellurium nanowires (NWs), nanotubes (NTs) and trifold nanorods (NRs) were synthesized using a facile, environmentally benign solvothermal method with ethylene glycol as solvent, polyvinylpyrrolidone as surfactant and non-hazardous ascorbic acid as a reducing agent. By adjusting the amounts of the surfactant and the reducing agent, Te NWs, NTs and trifold NRs were prepared. The diameter of the Te NWs and NTs are 30–40 nm and 120–150 nm, respectively. A morphology evolution diagram based on different amounts of polyvinylpyrrolidone and ascorbic acid aqueous solution are presented. The effects of temperature are also investigated meticulously. The growth mechanism of the Te NTs and trifold Te NRs are discussed based on the crystallization law. The photoelectrical properties of the Te NWs and trifold Te NRs were measured. The photocurrent and responsivity of the photodetector based on Te NWs are 0.17 mA and 25.8 A W−1, respectively.

We present a detailed study on near-infrared (NIR) reflection spectra of Cu nanowire arrays (NWAs) which are embedded in porous anodic alumina oxide templates and with pore diameters from 35 nm to 80 nm. We find that the NIR reflection of these samples is out of the frequency regime for surface-plasmon resonance induced by intra-and inter-band excitations. However, the intensity of the NIR reflection of Cu NWAs depends strongly on sample parameters and temperature. The measurements are carried out at temperatures setting to be 4 K, 77 K, 200 K, and at room temperature. The optical response of the Cu NWAs in NIR bandwidth is attributed to localized surface-plasmon oscillations and the NIR reflectance increases with temperature up to room-temperature. The physical mechanisms behind these interesting findings are discussed.

The magnetic nanoparticle (NP) chain has attracted great concern due to its potential applications in magnetic recording, electron nano-devices, micro-mechanical sensors, and drug delivery. Here, we demonstrate the controllable preparation of magnetic Ni NP chains using electrochemical corrosion methods. Ni/Cu multi-segmented nanowires (NW) were prepared by alternately depositing Ni and Cu into the pores of an anodic aluminum oxide (AAO) template, then highly uniform Ni NP chains were obtained by immersing Ni/Cu NWs/AAO composite membrane in a 15 wt% NaOH solution for about 50 min. The reaction mechanism is proposed based on electrochemical corrosion, in which Cu serviced as the anode is corroded and Ni serviced as the cathode are retained in the NaOH electrolyte solution. Particle size and separation of the Ni NP chains can be easily adjusted and the smallest particle size and particle spacing reached to 6 nm and 15 nm, respectively. This strategy developed herein can be expected to be general route for the controllable fabrication of metallic NP chains.

This communication reports an approach to fabricate large-scale ultrathin open-ended porous TiO2 membranes (UOP-TMs) with ordered straight-through pores. Bi nanodot arrays on Si substrates are obtained by using the UOP-TMs as surface patterning masks.

In this paper, we adopted a voltage compensation mode and prepared a porous anodic alumina oxidation template with very uniform pore diameter even when the pore length reaches to 60 μm. This compensation voltage mode can effectively compensate the uneveness of the pore size caused by ion concentration decrease at the bottom of the pores directly involved in the anodic oxidation in the continuously growing process of holes, and the chemical corrosion effect of the pre-formed hole by electrolyte. This very uniform pore diameter alumina oxidation template will be helpful for further studies on the properties related to diameter of nanowires.

One-dimensional noble-metal Ag nanoparticle chains have been prepared by electrodepositing Ag/Bi superlattice nanowires in a porous anodic alumina oxide (AAO) template and following an annealing process in vacuum. It is found that Bi, as a sacrificial metal, can be removed completely after annealing at 450 °C with a vacuum degree of 10(-5) Torr. The regulation of particle size, shape and interparticle spacing of Ag NP chains has been realized by adjusting the segment length of the Ag/Bi superlattice nanowires and the annealing condition. With an extension of the annealing time, it is observed that Ag particles display the transform trend from ellipsoid to sphere. Our findings could inspire further investigation on the design and fabrication of metal nanoparticle chains.

A total of 107 soil samples were taken from the city of Qingdao, Shandong Province, China. Soil water retention data at 2.5, 6, 10, 33, 100, 300, and 1500 kPa matric potentials were measured using a pressure membrane apparatus. Multiple linear regression (MLR) was used to develop pedotransfer functions (PTFs) for single point estimation and van Genuchten parameter estimation based on readily measurable soil properties, i.e ., MLR-based point (MLRP) PTF and MLR-based parametric (MLRV) PTF. The double cross-validation method was used to evaluate the accuracy of PTF estimates and the stability of the PTFs developed in this study. The performance of MLRP and MLRV PTFs in estimating water contents at matric potentials of −10, −33, and −1 500 kPa was compared with that of two existing PTFs, the Rawls PTF and the Vereecken PTF. In addition, geostatistical analyses were conducted to assess the capabilities of these PTFs in describing the spatial variability of soil water retention characteristics. Results showed that among all PTFs only the Vereecken PTF failed to accurately estimate water retention characteristics. Although the MLRP PTF can be used to predict retention characteristics through traditional statistical analyses, it failed to describe the spatial variability of soil water retention characteristics. Although the MLRV and Rawls PTFs failed to describe the spatial variability of water contents at a matric potential of −10 kPa, they can be used to quantify the spatial variability of water contents at matric potentials of −33 and −1500 kPa.

As soil cation exchange capacity (CEC) is a vital indicator of soil quality and pollutant sequestration capacity, a study was conducted to evaluate cokriging of CEC with the principal components derived from soil physico-chemical properties. In Qingdao, China, 107 soil samples were collected. Soil CEC was estimated by using 86 soil samples for prediction and 21 soil samples for test. The first two principal components (PC1 and PC2) together explained 60.2% of the total variance of soil physico-chemical properties. The PC1 was highly correlated with CEC (r =0.76, P r =0.03). The PC1 was then used as an auxiliary variable for the prediction of soil CEC. Mean error (ME) and root mean square error (RMSE) of kriging for the test dataset were −1.76 and 3.67 cmol c kg −1 , and ME and RMSE of cokriging for the test dataset were −1.47 and 2.95 cmol c kg −1 , respectively. The cross-validation R 2 for the prediction dataset was 0.24 for kriging and 0.39 for cokriging. The results show that cokriging with PC1 is more reliable than kriging for spatial interpolation. In addition, principal components have the highest potential for cokriging predictions when the principal components have good correlations with the primary variables.

AbstractThe angular dependences of the transmission of a one-dimensional photonic crystal based on porous anodic aluminum oxide are studied in the wavelength range of 320–1200 nm. The possibility of using porous one-dimensional photonic crystals based on aluminum oxide as selective narrowband optical filters and mirrors is studied.

One hydroxyaluminum-montmorillonite complex (HyAl-Mt), two hydroxyiron-montmorillonite complexes (HyFe-Mts) with different iron contents, and three hydroxyiron/aluminum-montmorillonite complexes (HyFeAl-Mts) with various Fe:Al molar ratios were synthesized. Behavior and kinetics of phosphate (P) sorption on selected Mt-complexes mentioned above were investigated under acidic conditions. The results indicated that the intercalations of polymeric HyFe and/or HyAl ions in interlayers of Na-saturated montmorillonite (Na-Mt) caused significant changes in surface properties of the Na-Mt, such as cation exchange capacity, specific surface area, pH at zero point of charge. In pH range tested (3.0–6.5), P adsorption on the Mt-complexes decreased with increasing pH, whereas the effect became weaker with increasing Fe contents in the Mt-complexes. The adsorption capacities of the HyFeAl-Mts were greater than those of the HyAl-Mt and HyFe-Mt, which could be attributed to decreasing crystallinity of Fe and Al oxides in the HyFeAl-Mts. The equilibrium adsorption of P on the Mt-complexes could be well described using the Langmuir isotherm, and the kinetics of P adsorption could be well described by both the pseudo-second-order and Elovich models. An increase in Fe contents in the Mt-complexes could enhance the initial kinetic rate of P adsorption, as suggested by the Elovich models. It is inferred that a great number of Fe-related active sorption sites have been located on the outer surfaces of the HyFe-Mt, as indicated by extremely high α value in the Elovich model. Previous studies focusing mainly on P sorption on HyAl-Mt complexes might have underestimated the contributions of Mt-complexes to P retention in acidic soils high in Fe contents.

Cu nanowires with different preferred orientations were successfully fabricated in porous anodic alumina membrane (PAAM) templates by an electrochemical method. Thermal expansion of as-prepared and...

This communication reports an approach to fabricate large-scale ultrathin open-ended porous TiO2 membranes (UOP-TMs) with ordered straight-through pores. Bi nanodot arrays on Si substrates are obtained by using the UOP-TMs as surface patterning masks.

Anodic aluminum oxide based photonic crystals with periodic porous structure have been prepared using voltage compensation method. The as-prepared sample showed an ultra-narrow photonic bandgap. Asymmetric line-shape profiles of the photonic bandgaps have been observed, which is attributed to Fano resonance between the photonic bandgap state of photonic crystal and continuum scattering state of porous structure. And the exhibited Fano resonance shows more clearly when the sample is saturated ethanol gas than air-filled. Further theoretical analysis by transfer matrix method verified these results. These findings provide a better understanding on the nature of photonic bandgaps of photonic crystals made up of porous materials, in which the porous structures not only exist as layers of effective-refractive-index material providing Bragg scattering, but also provide a continuum light scattering state to interact with Bragg scattering state to show an asymmetric line-shape profile.

Boshan is an industrial city in the center of Shandong Province where ground water is the only source for the urban water supply. The major water resource is fracture-karst water in the middle Ordovician carbonate rocks. Based on the hydrogeologic investigation and mapping in this area, the authors studied the geologic and hydrogeologic settings, the major pollution sources and the pathways of contamination, the principal contaminants, and their spatial distribution in ground water. The ground-water quality has also been estimated by the fuzzy mathematic method. The geostatistical method, such as the kriging method, was taken to simulate spatial distribution of the contaminants. The grey system method was adopted to forecast future contamination. An attempt at the remediation of Cr{sup 6+} contamination in fracture-karst water was also discussed. Finally, some proposals for the protection of the ground-water environment in Boshan District are offered.

Delta-MnO(2) coatings on clay substrates tend to be poorer in crystallinity as compared with their discrete counterparts, which may be of environmental significance for adsorption and oxidation of contaminants. Discrete delta-MnO(2) particles and three delta-MnO(2)-coated montmorillonite complexes with varying MnO(2) loadings (4.8-34.9%) were synthesized, and oxidative decolorization of methylene blue (MB) by the synthetic materials was investigated in batch systems. Results showed that oxidative decolorization of MB increased with increasing loading of Mn-oxide coatings, whereas oxidation capacity of the coatings, on the basis of unit mass of MnO(2), tended to decrease. Initial reaction rate of MB oxidation by both delta-MnO(2) coatings and their discrete counterpart increased linearly with increasing Mn-oxide loadings, but the rate of the former was higher than that of the latter. An increase in humic acid concentration displayed a progressively enhanced promotive effect on MB decolorization, whereas the promotive effect was greatly suppressed at lower pH.

The phenomenon of extraordinary and multi-broadband optical transmission through sub-wavelength metallic grating with symmetry breaking has been theoretically investigated. Under normal incident light, the radiative and dark modes appear in adjacent slits of the grating with asymmetric heights. Through the destructive interference of alternative radiative and dark modes, multiple broadband transmission and enhanced light propagation is realized. The counter-propagating light circulation results in sharp dips in the transmission spectrum. These characteristics of the asymmetric grating could provide highly controllable ways to design novel devices.

Multibranched TiO2 nanotubes have been controllably fabricated through a two-step anodization method. By tailoring the diameter ratio of the stem and branch accurate by multibranched, such as two-,...

In this work, we demonstrated the use of a promising sensor based on alumina Photonic Crystals (PC) which can be applied in the field of gas detection owing to the well structured PC with an ultra-narrow Photonic Bandgap (PBG), of which the full width at half maximum is only 30 nm. This type of PC was prepared successfully by using a compensation voltage mode method, which can effectively compensate for the chemical corrosion and the slowing down of ion exchange, resulting in a uniform diameter of the pores in the anodic alumina oxidation (AAO) from beginning to end. The as-prepared sample was applied to detect the concentration of organic vapor, such as ethanol, in this experiment. A large PBG shift is achieved when the concentration of ethanol changes, and the mechanism was also discussed theoretically. This sensor had a good repeatability due to the chemical and physical stability of the matrix material (alumina). These results indicate the potential applications of the as-prepared AAO based PC in the sensing field.

In this study, the free-standing and open-ended TiO2 nanotube arrays with large area are synthesized under high field anodization. The membrane is firstly self-detached from Ti foil during anodization followed by a pore opening process of in situ field-assisted chemical dissolution. A model of stress accumulation is proposed to explain the self-detachment of the as-formed TiO2 nanotube membrane from the underlying Ti substrate. It is believed that the stress accumulation in the membrane is the collective effects of the stress generation during tube growth and the stress release due to chemical dissolution. When the stress accumulates to a critical value, the TiO2 nanotube membrane would be self-detached from the Ti substrate. It is found that the magnitude of stress is associated with the thickness of a stressed layer rather than the thickness of the as-formed TiO2 membrane. By changing the anodization parameters, the stress accumulation rate can be facilely controlled, which finally determines the detaching time and thickness of the detached membrane.

A method of using the superlattice nanowire with epitaxial growth to study the relationship between the crystal orientation and corresponding growth rate for the electrodeposited nanowire is proposed. The relationship between growth rate and orientation of two metals Ni and Cu was studied through analysis of the epitaxial growth of Ni/Cu superlattice nanowires. Three samples with different periodic lengths were prepared by an electrodeposition method and analyzed to compare the segment lengths of nanowires with different crystalline orientations. The quantitative analysis result indicates that the growth rate of different planes exist ν(220) : ν(111) = 1.25–1.31 for Ni, and ν(220) : ν(111) = 1.32–1.41 for Cu, which qualitatively follow the Bravais rule. The quantitative analysis for the relationship between growth rate and orientation is important for the effective control of the uniform growth of the electrodeposited nanowires.

A facile and universal synthetic approach for preparing superlattice nanowire (SLNW) arrays is developed. In this method, two kinds of elements are alternately electrodeposited into the holes of the anodic alumina oxide (AAO) template, automatically in separate electrolytes by a programmed device. This method is not restricted by the relative values of the reduction potentials of the elements, and the deposition of each element can be controlled independently. Three kinds of representative SLNW arrays containing noble-metal material (Ag/Ni), thermoelectric material (Bi/Sb) and magnetic material (Ni/Cu) with adjustable segment length are fabricated successfully.