Genome-Wide Identification and Characterization of the NAC Gene Family and Its Involvement in Cold Response in Dendrobium officinale.

The NAC (NAM, ATAF1/2 and CUC2) gene family is one of the largest plant-specific transcription factor families, functioning as crucial regulators in diverse biological processes such as plant growth and development as well as biotic and abiotic stress responses. Although it has been widely characterized in many plants, the significance of the NAC family in Dendrobium officinale remained elusive up to now. In this study, a genome-wide search method was conducted to identify NAC genes in Dendrobium officinale (DoNACs) and a total of 110 putative DoNACs were obtained. Phylogenetic analysis classified them into 15 subfamilies according to the nomenclature in Arabidopsis and rice. The members in the subfamilies shared more similar gene structures and conversed protein domain compositions. Furthermore, the expression profiles of these DoNACs were investigated in diverse tissues and under cold stress by RNA-seq data. Then, a total of five up-regulated and five down-regulated, cold-responsive DoNACs were validated through QRT-PCR analysis, demonstrating they were involved in regulating cold stress response. Additionally, the subcellular localization of two down-regulated candidates (DoNAC39 and DoNAC58) was demonstrated to be localized in the nuclei. This study reported the genomic organization, protein domain compositions and expression patterns of the NAC family in Dendrobium officinale, which provided targets for further functional studies of DoNACs and also contributed to the dissection of the role of NAC in regulating cold tolerance in Dendrobium officinale.

Critical review on modified floating photocatalysts for emerging contaminants removal from landscape water: problems, methods and mechanism.

Due to the disorderly discharge in modern production and daily life of people, emerging contaminants(ECs) began to appear in landscape water, and have become a key public concern. Because of the unique characteristics of landscape water, it is difficult to efficiently remove ECs either by natural purification or by traditional large-scale sewage treatment facilities. The ideal purification method is to remove them while maintaining a beautiful environment. Possessing the feature of low-density, floating photocatalysts could harvest sufficient light on the surface of the water for photocatalytic degradation, which may be an important supplement for ECs treatment in landscape water. This paper gave a review related to floating photocatalysts and proposed an idea of combining floating photocatalysts to construct bionic photocatalytic materials for contaminative landscape water treatment. Six types of common floating substrates and corresponding applications for floating photocatalysts were concluded in this paper, and the main problem leading to the low efficiency of photocatalysts and three corresponding three improvement strategies were discussed. Besides, the modification mechanisms of photocatalysts were discussed thoroughly. On this basis, the engineering application prospects of bionic photocatalytic materials were proposed to remove ECs in landscape water.

Progress in semiconductor materials for photocathodic protection: Design strategies and applications in marine corrosion protection.

Metal protection of offshore equipment is very complicated owing to the complex marine environment. Photocathodic protection (PCP) is one of the popular research topics in marine metal protection. The protection efficiency of photoanode depends largely on the photoelectric properties of semiconductor materials, viz. the process of charge separation, charge migration, and light absorption. In this article, the enhancement strategies, photoelectrochemical properties, and electron transfer mechanisms of different composites for PCP were reviewed and highlighted. Some photoanodes with unusual and striking properties were emphasized. In addition, the outlooks and challenges of the application of PCP and the design of photoanodes materials are proposed.

Synthesis of environmental-friendly ion-imprinted magnetic nanocomposite bentonite for selective recovery of aqueous Sc(III).

A novel reusable ion imprinted nanocomposite magnetic bentonite(IIPNMB) was prepared for selective recovery of aqueous scandium. Based on the fact that oxyphosphorus functional groups in sodium tripolyphosphate have good affinity to Sc(III) and chitosan is rich in hydroxy and amino active sites, they were chosen to build ion imprinted layers. Mesoporous IIPNMB showed good adsorption performance. The pseudo second-order kinetic model and Langmuir model fit the experimental data. According to XPS features, the amino, hydroxyl, PO and PO bonds of the adsorbents had electrostatic interaction and complexation with Sc(III), leading to the good selectivity of IIPNMB for Sc(III). In addition, the material atomic structure was proposed based on the chemical structure of IIPNMB for DFT calculation of ion imprinting adsorption, which clearly proved that the adsorption process of Sc(III) was stable, and it gave another proof for the mechanism of the selective extraction.

Metasurface-based Fourier lens fed by compact plasmonic optical antennas for wide-angle beam steering.

A Fourier lens can perform the Fourier transform of an incident wavefront at the focal plane. This paper reports a metasurface-based Fourier lens fed by compact plasmonic optical antennas for wide-angle beam steering. The metasurface, composed of six elements with different configurations covering the 2π phase range, features a large field-of-view (FOV) of ±50°. A novel plasmonic optical antenna for broadside radiation is then designed as the feed source of the metasurface. The proposed antenna has ultra-compact size of 0.77λ × 1.4λ, and achieves a high directivity of 9.6 dB and radiation efficiency of over 80% at the wavelength of 1550 nm. Full-wave simulations are carried out to evaluate the performances of the designed metasurface-assisted beam steering device. The results show that this device can achieve a maximum directivity of 21.5 dB at broadside radiation. Compared to conventional Yagi-Uda antenna feed, a directivity enhancement of about 2.7 dB can be obtained, exhibiting a great superiority of the proposed feed antenna. In addition, a large beam steering range of ±50° can be achieved with an acceptable gain drop of 2.83 dB. With the advantages of wide beam steering range, good radiation characteristics, small footprint, and ease of integration, the proposed metasurface-assisted beam steering device would be a promising candidate for integrated photonic applications, including wireless optical communications, light detection and ranging, and augmented reality.

Genome-Wide Characterization and Expression Analysis of HD-ZIP Gene Family in Dendrobium officinale.

The homeodomain-leucine zipper (HD-ZIP) gene family, as one of the plant-specific transcription factor families, plays an important role in regulating plant growth and development as well as in response to diverse stresses. Although it has been extensively characterized in many plants, the HD-ZIP family is not well-studied in Dendrobium officinale, a valuable ornamental and traditional Chinese medicinal herb. In this study, 37 HD-ZIP genes were identified in Dendrobium officinale (Dohdzs) through the in silico genome search method, and they were classified into four subfamilies based on phylogenetic analysis. Exon-intron structure and conserved protein domain analyses further supported the prediction with the same group sharing similar gene and protein structures. Furthermore, their expression patterns were investigated in nine various tissues and under cold stress based on RNA-seq datasets to obtain the tissue-specific and cold-responsive candidates. Finally, Dohdz5, Dohdz9, and Dohdz12 were selected to validate their expression through qRT-PCR analysis, and they displayed significantly differential expression under sudden chilling stress, suggesting they might be the key candidates underlying cold stress response. These findings will contribute to better understanding of the regulatory roles of the HD-ZIP family playing in cold stress and also will provide the vital targets for further functional studies of HD-ZIP genes in D. officinale.

High-efficiency unidirectional vertical emitter achieved by an aperture-coupling nanoslot antenna array.

Coupling light from in-plane guided light into free space or optical fibers is crucial for many photonic integrated circuits and vice versa. However, traditional grating couplers or waveguide grating antennas suffer from low upward coupling efficiency due to the light radiating in both upward and downward directions simultaneously. In this paper, a compact aperture-coupling nanoslot antenna array is proposed for high-efficiency unidirectional radiation, where a two-dimensional high-contrast grating (HCG) is employed as a mirror to reflect the undesired downward radiation. Upon the HCG separated by a low-index spacing layer, a thin silver layer is deposited. Finally, a series of H-shaped slots are patterned on the silver thin film to arrange the aperture fields and radiate the in-plane guided light into free space. The proposed nanoslot antenna array features a front-to-back ratio (F/B) over 10 dB within the wavelength range of 1500 ∼ 1600 nm. At the same time, a high radiation efficiency of over 75% and a maximum radiation efficiency of 87.6% are achieved within the 100 nm bandwidth. The high-efficiency unidirectional antenna array is promising for the integrated photonic applications including wireless optical communications, light detection and ranging, and fiber input/output couplers.

Green synthesis of reusable super-paramagnetic diatomite for aqueous nickel (II) removal.

Adsorption is an effective method for treating wastewater containing nickel due to its minimal equipment requirements and flexible operation. Therefore, an environmental friendly, inexpensive, efficient and recyclable adsorbent is needed. In this work, a reusable dual-functional super-paramagnetic adsorbent was prepared by combining APTES (3-Aminopropyltriethoxysilane) and EDTA (ethylenediaminetetraacetic acid disodium) with magnetic diatomite for the removal of Ni2+. It is named diatomite/CoFe2O4@APTES-EDTA (DECFASEs). The synthetic material was characterized and studied by XRD (X-ray Powder Diffractometer), FTIR (Fourier Transform Infrared Spectrometer), SEM (Scanning Electron Microscope), TEM (Transmission Electron Microscope), EDS (Energy Dispersive Spectrometer), VSM (Vibrating-Sample Magnetometer), BET (Brunauer-Emmett-Teller) method, Zeta potential analyzer and XPS (X-ray Photoelectron Spectroscopy), respectively. The performance of adsorption Ni2+ by DECFASEs was studied on effect of pH, reaction time and initial concentrations. The adsorption and desorption capacity and recyclability of the adsorbent material were estimated. A adsorption kinetic data had a significant correlation with the pseudo second-order kinetic and also adsorption isotherm data corresponded well with Freundlich adsorption isotherm. The maximum adsorption capacity of the adsorbent material was 19.22 mg/g. The Ni2+ adsorption capacity of DECFASEs decreased slightly from 9.11 to 8.25 mg/g after 4 recycles. The XPS results of DECFASEs before and after Ni2+ uptake showed N and O participated in the complexation of Ni2+ in the adsorption process, which verified the chemical interaction between Ni2+ and DECFASEs. Modified-diatomite is a promising adsorbent for aqueous Ni2+ removal.

Grating lobe suppression in optical phased arrays by loading near-wavelength grating.

Optical phased arrays based on optical waveguides are compelling components enabling efficient and accurate beam steering. However, to avoid crosstalk between the waveguides, the element pitch is typically larger than one wavelength, which gives rise to grating lobes in real space. In this Letter, we report that near-wavelength gratings can be employed to suppress the grating lobes by utilizing the angular low-pass-filter characteristics. The properly designed near-wavelength grating acts as an angle-sensitive transmission structure. Nearly 100% transmissivity can be realized at small incident angles. However, it quickly declines to a low level when the incident angle is over the critical one. Then, a simple line current array is utilized to demonstrate the grating lobe suppression effect with the grating designed for TE-polarized incidence. Finally, we demonstrate that by loading the proposed grating designed for TM-polarized incidence upon a waveguide grating array with a 2.4 µm pitch, a grating lobe suppression of 10 dB can be achieved when scanning up to ±14∘.

Removal of heavy metals in medical waste incineration fly ash by Na2EDTA combined with zero-valent iron and recycle of Na2EDTA: Acolumnar experiment study.

In this study, an effective circulating system was developed to remove heavy metals in medical waste incineration (MWI) fly ash. MWI fly ash (MWIFA)-column experiments were performed to remove Cu, Pb, Zn, Cd, and Ni from MWIFA using EDTA disodium (Na2EDTA). Iron-column experiments were conducted to study the removal effect of zero-valent iron on the five heavy metals from washing wastewater. Toxicity Characteristic Leaching Procedure (TCLP) test method was employed to evaluate heavy metals toxicity of MWIFA residues generated after 0-0.2 mol/L Na2EDTA solution treated. After being washed by 0.2 mol/L Na2EDTA solution, TCLP leaching values of Cu, Pb, Zn, Cd, and Ni were the lowest and satisfied the standard (GB 5085.3-2007), and the leaching values were 58.4 ± 2.0 mg/L, 2.81 ± 0.14 mg/L, 64.3 ± 4.0 mg/L, 0.156 ± 0.005 mg/L, 0.381 ± 0.006 mg/L. Concentrations of Cu, Pb, Zn, Cd, and Ni in iron-column effluent were reduced by 99.7%, 91.6%, 91.6%, 75.4%, and 75.7%, respectively. Na2EDTA was recovered and recycled to the removal of heavy metals from MWIFA. Comparing new Na2EDTA solution with recycled Na2EDTA solution, recycled Na2EDTA and water could be reutilized to dispose MWIFA. The removal efficiencies of Cu, Pb, Zn, Cd, and Ni by recycled 0.2 mol/L Na2EDTA solution were 67.1%, 68.8%, 63.2%, 73.9%, 50.7%, respectively, the removal efficiencies using recovered Na2EDTA decreased by 2.6%, 3.9%, 3.3%, 4.2%, and 1.6%, respectively. Successive batch experiments were also conducted to evaluate industrialization potential and reusable times for recycled Na2EDTA. After four recirculation cycles, extraction efficiencies of Pb and Cd (removal efficiency at different cycles divided by removal efficiency of new Na2EDTA) declined toward 80%. Results from this research indicated that this circulating system possessed industrialization potential. Implications: An effective circulating system was developed to remove heavy metals in MWI fly ash (MWIFA). Integration of Na2EDTA with Fe0 promoted the removal of heavy metals from MWIFA. Na2EDTA, NaCl and water were stepwise extracted from iron-column effluent, respectively. Recovered Na2EDTA can still effectively remove heavy metals from MWIFA. Results from this research indicated that this circulating system possessed industrialization potential.

Green synthesis of reusable multifunctional γ-Fe2O3/bentonite modified by doped TiO2 hollow spherical nanocomposite for removal of BPA.

Eco-friendly treatment of refractory pollutants in wastewater is still full of challenge in catalytic oxidation and adsorption. In this study, based on the concept of green chemistry, sulfur-doped titanium dioxide hollow spheres modified by surfactant loaded on magnetic bentonite (CST/γ-Fe2O3-BT) is synthesized in two steps, and bisphenol A (BPA) was chosen as the representative organic pollutant. These materials were characterized by means of XRD, FTIR, SEM, EDS, TEM, XPS, BET, and VSM techniques. The adsorption and photodegradation behavior of CST/γ-Fe2O3-BT were examined. The Langmuir isotherm exhibited a better fit with a maximum adsorption capacity of 77.36 mg/g. At pH 7, the reaction rate constant (k) of the BPA photocatalytic degradation by product was 0.00104 min-1, and the adsorption equilibrium constant (K) was 0.04034L/mg. In addition, the composite can be recovered from the reaction mixture by applying an external magnetic field due to the existence of the superparamagnetic iron oxide nanoparticles in the construct. The recovered particles retained their catalytic activity which the catalytic activity of the material still reached 91% of the first catalytic experiment after 5 repetitive experiments. Results infer that the material has excellent reusability. Thus, CST/γ-Fe2O3-BT is a significant candidate for the treatment of recalcitrant organic pollutants in wastewater.

Synthesis of amino-functionalized bentonite/CoFe2O4@MnO2 magnetic recoverable nanoparticles for aqueous Cd2+ removal.

Magnetic nano-composite materials have been attracting considerable attention due to their unique properties and versatile applications. In this study, a novel magnetic amino-functionalized conjugate adsorbent, named as bentonite/CoFe2O4@MnO2-NH2 (BCFMNs), was synthesized by combining APTES and MnO2 with magnetic bentonite. XRD, FT-IR, SEM, EDS, TEM, and VSM techniques were used to characterize its structure and magnetic properties. Results were in indicative of productive synthesis, well-defined architecture and satisfactory magnetism. BET examinations illustrated 84.97m2/g of specific surface area, 0.15cm3/g of pore volume and 7.02nm average pore size. The effect parameters such as adsorbent dosage, contact time, initial concentration and ion selectivity and recycling were evaluated and optimized systematically. Also, the metal concentrations were measured by ICP-MS spectrometer. The feasibility of the BCFMNs for removal of Cd2+ from aqueous solution was also evaluated by adsorption experiments with the maximal adsorption efficiency for Cd2+ up to 98.88%. Cd2+ adsorption could be interpreted by the Langmuir adsorption isotherm and the maximum adsorption capacity was 115.79mg/g. The results revealed that the adsorbent still had higher selectivity of Cd2+ removal even in the presence of high concentration coexisting cations. The as-prepared magnetic conjugate adsorbent could be recycled by taking advantage of its magnetic properties. The distinctive structure of BCFMNs and its excellent adsorption performance of cadmium reflects its prospective application in water treatment.

Assessment of heavy metal in coal gangue: distribution, leaching characteristic and potential ecological risk.

In the process of excavation and utilization of the coal gangue hill, gangue at different weathering degree was exposed to the environment, which can be harmful to the surroundings. In order to find the law of heavy metal release and to evaluate the potential ecological risk, five kinds of coal gangue at different weathering degrees were collected from a coal mine named Suncun, an over 100-year-old mine of Xinwen coal mining field located in Tai'an city, Shandong Province of China. Samples were processed with microwave digestion for total content determination of heavy metals, and another part of samples was processed by Tessier sequential extraction for chemical forms analysis. Leaching tests at various pH were carried out to investigate the release of heavy metal. The laws of transformation and release of heavy metals were discussed and potential ecological risk was evaluated. The results indicated that the weathering degree had a significant impact on the content of heavy metal. Exchangeable and carbonate fractions of Cr and Pb were a large proportion of the total and should attract great attention. Potential ecological risk was at strong level (light black) and was up to very strong level (deep black) because of Cd. But Cr had contributed the most for gray gangue, which was 71% of the total. The species of heavy metal in gangue changed due to weathering and lead to the difference of the leaching characteristic and risk.

Size distribution and source of heavy metals in particulate matter on the lead and zinc smelting affected area.

In order to understand the size distribution and the main kind of heavy metals in particulate matter on the lead and zinc smelting affected area, particulate matter (PM) and the source samples were collected in Zhuzhou, Hunan Province from December 2011 to January 2012 and the results were discussed and interpreted. Atmospheric particles were collected with different sizes by a cascade impactor. The concentrations of heavy metals in atmospheric particles of different sizes, collected from the air and from factories, were measured using an inductively coupled plasma mass spectrometry (ICP-MS). The results indicated that the average concentration of PM, chromium (Cr), arsenic (As), cadmium (Cd) and lead (Pb) in PM was 177.3 ±â€¯33.2 µg/m3, 37.3 ±â€¯8.8 ng/m3, 17.3 ±â€¯8.1 ng/m3, 4.8 ±â€¯3.1 ng/m3 and 141.6 ±â€¯49.1 ng/m3, respectively. The size distribution of PM displayed a bimodal distribution; the maximum PM size distribution was at 1.1-2.1 µm, followed by 9-10 µm. The size distribution of As, Cd and Pb in PM was similar to the distribution of the PM mass, with peaks observed at the range of 1.1-2.1 µm and 9-10 µm ranges while for Cr, only a single-mode at 4.7-5.8 µm was observed. PM (64.7%), As (72.5%), Cd (72.2%) and Pb (75.8%) were associated with the fine mode below 2.1 µm, respectively, while Cr (46.6%) was associated with the coarse mode. The size distribution characteristics, enrichment factor, correlation coefficient values, source information and the analysis of source samples showed that As, Cd and Pb in PM were the typical heavy metal in lead and zinc smelting affected areas, which originated mainly from lead and zinc smelting sources.

[Characteristics and Sources of Elements in Atmospheric Dust Fall in Zhuzhou City, Central China].

To study the concentration characteristics as well as sources of elements and heavy metal pollution in atmospheric dust fall in Zhuzhou City, 144 samples from 12 sites in the Zhuzhou urban area were collected from January to December in 2012 and 28 kinds of elements in the samples were analyzed. The results showed that the dust fall quantities of the industrial areas and mixed commercial and residential (MCR) areas were, respectively, 89.46 g·m-2 and 33.20 g·m-2 and the range of all sample points was 23.14-114.67 g·m-2. There were 10 elements (Na, Mg, Al, K, Ca, Ti, Mn, Fe, Zn, Pb) in the industrial areas as well as 8 elements in the MCR areas, for which the contents greatly exceeded 1000 mg·m-1 in the atmospheric dust fall. The Zn and Pb contents exceeded 10000 mg·kg-1 in the dust fall of the industrial areas, which were far higher than those in the Earth's crust. The main sources of dust fall in Zhuzhou City were metal smelting, shallow ground dust, vehicle emissions, construction dust, and industrial production with specific elements (Mo, Ba). Correlation analysis, principal component analysis (PCA), and analysis of transportation characteristics showed that 13 elements (Mn, Fe, Co, Cu, Zn, As, Se, Ag, Cd, Sn, Sb, Tl, Pb) in dust fall mainly came from waste gas emissions of industrial areas in Zhuzhou, in which 7 heavy metal elements (Cu, Zn, As, Ag, Cd, Sb, Pb) caused serious pollution. The contents of heavy metals in the industrial areas were 7.4 to 4079.4 times the contents defined in China soil elements background values, whereas those in the MCR areas were 3.6 to 1413.4 times the soil background values. Cd was the highest background ratio element. The degree of contamination was clearly higher in the industrial areas than in the MCR areas.

Thallium at the interface of soil and green cabbage (Brassica oleracea L. var. capitata L.): soil-plant transfer and influencing factors.

Thallium (Tl) is a non-essential and toxic trace metal found in many plants, but it can accumulate at particularly high concentration in green cabbage (Brassica oleracea L. var. capitata L.). The aim of this study is to explore the transfer and accumulation of Tl at the interface of rhizospheric soil and green cabbage from a long-term Tl contaminated site in southwestern Guizhou Province, China. Influencing factors such as Tl distribution in various soil fractions and physical-chemical characteristics of rhizospheric soil were also investigated. Our results demonstrated that green cabbage had high accumulation of Tl, with most bioconcentration factor (BF) values exceeding 1, and up to a maximum level of 11. The enrichment of Tl in the green cabbage tissues followed a descending order, i.e. old leaves>fresh leaves>stems≈roots. The stems functioned as a channel for Tl transportation to the leaves, where most of the Tl (greater than 80%) was found to accumulate. In the rhizospheric soils, 62-95% of Tl existed in the residual fraction, while lower concentrations of Tl (on average, 1.7% of total T1 in rhizospheric soil) were found in the water and acid soluble fractions. The major fraction of labile Tl was located in the reducible fraction (9%). Our results also suggested that the uptake and enrichment of Tl in green cabbage were affected by Tl concentrations, soil water content, soil pH, soil organic material (SOM) and cation exchange capacity (CEC) in rhizospheric soil.