Electromagnetically Induced Transparency and Refractive Index Sensing for a Plasmonic Waveguide with a Stub Coupled Ring Resonator

A plasmonic refractive index sensor based on electromagnetically induced transparency (EIT) composed of a metal-insulator-metal (MIM) waveguide with stub resonators and a ring resonator is presented. The transmission properties and the refractive index sensitivity are numerically studied with the finite element method (FEM). The results revealed an EIT-like transmission spectrum with an asymmetric line profile and a refractive index sensitivity of 1057 nm/RIU are obtained. The coupled mode theory (CMT) based on transmission line theory is adopted to illustrate the EIT-like phenomenon. Multiple EIT-like peaks are observed in the transmission spectrum of the derived structures based on the MIM waveguide with stub resonator coupled ring resonator. To analyze the multiple EIT-like modes of the derived structures, the H _z field distribution is calculated. In addition, the effect of the structural parameters on the EIT-like effect is also studied. These results provide a new method for the dynamic control of light in the nanoscale.     

Enhancement of Emission Efficiency of Deep-Ultraviolet AlGaN Quantum Wells Through Surface Plasmon Coupling with an Al Nanograting Structure

The enhancement of the internal quantum efficiency (IQE) of deep-ultraviolet Al _x Ga_1-x N/Al _y Ga_1-y N (x < y) quantum wells (QWs) by fabricating one-dimensional Al nanogratings on a QW structure for inducing surface plasmon (SP) coupling is demonstrated. Through temperature-dependent photoluminescence (PL) measurement, the enhancements of IQE in different emission polarizations are illustrated. Due to the small difference in energy band level between the heavy/light hole and split-off valence bands, the IQEs of the transverse electric- (TE-) and transverse magnetic- (TM-) polarized emissions are about the same. When emission polarization is perpendicular to Al-grating ridges, the SP resonance mode for coupling with the QWs is dominated by localized surface plasmon (LSP). When emission polarization is parallel with Al-grating ridges, the coupled SP resonance mode may mix LSP and SP polariton. In this polarization, LSP can be excited because of the width fluctuation of a grating ridge. When the excitation laser polarization is perpendicular to Al-grating ridges, the strong LSP resonance at the excitation laser wavelength leads to stronger excitation and hence higher IQE levels.     

Oral fast-dissolving films containing lutein nanocrystals for improved bioavailability: formulation development, <Emphasis Type="Italic">in vitro</Emphasis> and <Emphasis Type="Italic">in vivo</Emphasis> evaluation

Lutein is widely used as diet supplement for prevention of age-related macular degeneration. However, the application and efficacy of lutein in food and nutritional products has been hampered due to its poor solubility and low oral bioavailability. This study aimed to develop and evaluate the formulation of oral fast-dissolving film (OFDF) containing lutein nanocrystals for enhanced bioavailability and compliance. Lutein nanocrystals were prepared by anti-solvent precipitation method and then encapsulated into the films by solvent casting method. The formulation of OFDF was optimized by Box-Behnken Design (BBD) as follows: HPMC 2.05% (w/v), PEG 400 1.03% (w/v), Cremophor EL 0.43% (w/v). The obtained films exhibited uniform thickness of 35.64 ± 1.64 μm and drug content of 0.230 ± 0.003 mg/cm² and disintegrated rapidly in 29 ± 8 s. The nanocrystal-loaded films with reconstituted particle size of 377.9 nm showed better folding endurance and faster release rate in vitro than the conventional OFDFs with raw lutein. The microscope images, thermograms, and diffractograms indicated that lutein nanocrystals were highly dispersed into the films. After administrated to SD rats, t _max was decreased from 3 h for oral solution formulation to less than 0.8 h for OFDF formulations, and C _max increased from 150 ng/mL for solution to 350 ng/mL for conventional OFDF or 830 ng/mL for nanocrystal OFDF. The AUC _0-24h of conventional or nanocrystal OFDF was 1.37 or 2.08-fold higher than that of the oral solution, respectively. These results suggested that drug nanocrystal-loaded OFDF can be applied as a promising approach for enhanced bioavailability of poor soluble drugs like lutein.     

Highly Sensitive Biochemical Sensor Based on Two-Layer Dielectric Loaded Plasmonic Microring Resonator

In this paper, we propose and design a highly sensitive optical biochemical sensor based on two-layer dielectric loaded surface plasmon polariton waveguide (TDLSPPW)-based microring resonator (MRR). By optimizing the structure parameters, the propagation length of the proposed waveguide is ~126 μm, which is about 3 times of that of the polymer dielectric loaded surface plasmon polariton waveguide (DLSPPW) reported. It is demonstrated that the TDLSPPW-based MRR is operated at the under-coupling state, along with the quality factor (Q) of 541.2 and extinction ratio (ER) of 12.2 dB. Moreover, the Q and ER are much more sensitive to the structure parameters of the waveguide, including the waveguide width w, total thickness t, and coupling gap W _gap, compared to the low refractive index (RI) layer thickness t ₂. The simulation results on the biochemical RI sensing show that the sensitivities of 408.7 and 276.4 nm/RIU for glucose concentration in urine and chemical gases can be achieved, respectively. It is believed that the proposed sensor has potential applications in photonic-integrated biochemical sensing.     

Fano Resonance Excited All-Optical XOR,XNOR, and NOT Gates with High Contrast Ratio

We have presented all-optical XOR, XNOR, and NOT gates using metal-insulator-metal (MIM)-coupled ring resonator. The performance of the device is evaluated by finite difference in time-domain (FDTD) method. The proposed gate utilizes a unique phenomenon of Fano resonance to excite logic OFF/ON state. Fano resonance has quite asymmetric resonance profile and the transmission spectrum of Fano profile abruptly drops to a minimum value at the resonance condition. Due to this unique resonance phenomenon, a large value of contrast ratio is obtained. The proposed XNOR gate offers a contrast ratio (C.R.) of 20.66 dB while XOR and NOT gates offer C.R. 12.8 and 18.8 dB respectively. The variation of contrast ratio is also studied against different input wavelength and it is reported that the obtained value of contrast ratio is an optimum value for the proposed structure. The device is compact sized with small dimension 0.31 λ₀², where λ₀?=?1.55 μm. The proposed device opens up the avenues for designing on-chip optical gates in the field of high-speed optical communication networks.     

Molecular characterization of microtubule-associated protein 1-light chain 3B in <Emphasis Type="Italic">Megalobrama amblycephala</Emphasis> fed with high fat/berberine diets

This study tested the effect of berberine on autophagy-related protein of Megalobrama amblycephala fed with high fat diet under different feeding modes. The full-length complementary DNA (cDNA) of microtubule-associated protein 1-light chain 3B (LC3B) was 1871 bp with an open reading frame of 378 bp encoding 125 amino acids. High homology at nucleotide and amino acid sequences to carp LC3B was revealed though sequence analysis. LC3B was mainly (P?< 0.05) expressed in hepatopancreas but lower in several peripheral tissues, including gill, intestine, kidney, and spleen. The fish (average initial weight 4.70?±?0.02 g) were fed with eight experiment diets containing two lipid levels (5 and 10%) or four berberine-feeding modes (without berberine, supplementing 50 mg/kg berberine at 2-week intervals, 4-week intervals, or continuous) for 8 weeks. The results showed that the numbers of autophagosomes and hepatopancreas LC3B messenger RNA (mRNA) expression levels were significantly (P?< 0.05) affected both by dietary lipid level and beberine feeding mode, and the highest (P?<?0.05) numbers of autophagosomes and LC3B expression levels were observed in fish at berberine continuous feeding mode groups. The findings may provide the molecular mechanisms underlying lipid metabolism and immune effect of berberine, which was associated with enhanced autophagy in fish.     

Nitrogen-induced variations in leaf gas exchange of spring triticale under field conditions

Nitrogen (N) is the key factor limiting photosynthetic processes and crop yield. Little is known about the response of leaf gas exchange of spring triticale (Triticosecale Wittm.) to N supply. The effect of N fertilizers on different gas exchange variables, i.e., photosynthetic rate (A), transpiration rate (E), stomatal conductance (g _s), instantaneous water use efficiency (WUE) and maximum quantum yield of photosystem II (PSII) (F _v/F _m), chlorophyll index (SPAD, soil–plant analysis development), and the relationship of these variables with yield were studied in spring triticale grown under field conditions. Six treatments of N—0, 90, 180, 90 + 30, 90 + 30 + 30 kg ha^?1 (applied as ammonium nitrate, AN) and one treatment of N 90 + 30 + 30 kg ha^?1 (applied as urea ammonium nitrate solution, UAN) were compared. The analysis of variance showed that throughout the triticale growing season, N fertilization had significant effects on A, WUE, g _s and SPAD. On average, N fertilizer application increased A values by 14–70%. E and F _v/F _m values were not influenced by N fertilization levels. The effect of growth stage and year on gas exchange variables and F _v/F _m and SPAD was found to be significant. At different growth stages, A values varied and maximum ones were reached at BBCH 31–33 (decimal code system of growth stages) and BBCH 59. With aging, values of A decreased independently of N fertilization level. The gas exchange variables were equally affected by both fertilizer forms. The interplay among grain yield, leaf gas exchange variables, F _v/F _m and SPAD of spring triticale was estimated. The statistical analysis showed that grain yield positively and significantly correlated with A and SPAD values throughout the growing season.     

Antimicrobial activity,cytotoxicity and chemical analysis of lemongrass essential oil (<Emphasis Type="Italic">Cymbopogon flexuosus</Emphasis>) and pure citral

The aim of this study was to determine the antimicrobial effects of lemongrass essential oil (C. flexuosus) and to determine cytotoxic effects of both test compounds on human dermal fibroblasts. Antimicrobial susceptibility screening was carried out using the disk diffusion method. Antimicrobial resistance was observed in four of five Acinetobacter baumannii strains with two strains confirmed as multi-drug-resistant (MDR). All the strains tested were susceptible to both lemongrass and citral with zones of inhibition varying between 17 to 80 mm. The mean minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of citral (mic—0.14 % and mbc—0.3 % v/v) was lower than that of Lemongrass (mic—0.65 % and mbc—1.1 % v/v) determined using the microtitre plate method. Cell viability using human dermal fibroblasts (HDF; 106-05a) was determined following exposure to both compounds and a control (Grapeseed oil) using the XTT assay and the IC₅₀ determined at 0.095 % (v/v) for citral and 0.126 % (v/v) for lemongrass. Grapeseed oil had no effect on cell viability. Live cell imaging was performed using the LumaScope 500 imaging equipment and changes in HDF cell morphology such as necrotic features and shrinkage were observed. The ability of lemongrass essential oil (EO) and citral to inhibit and kill MDR A. baumannii highlights its potential for use in the management of drug-resistant infections; however, in vitro cytotoxicity does suggest further tests are needed before in vivo or ex vivo human exposure.     

Oxygen transfer as a tool for fine-tuning recombinant protein production by <Emphasis Type="Italic">Pichia pastoris</Emphasis> under glyceraldehyde-3-phosphate dehydrogenase promoter

Effects of oxygen transfer on recombinant protein production by Pichia pastoris under glyceraldehyde-3-phosphate dehydrogenase promoter were investigated. Recombinant glucose isomerase was chosen as the model protein. Two groups of oxygen transfer strategies were applied, one of which was based on constant oxygen transfer rate where aeration rate was Q _O/V = 3 and 10 vvm, and agitation rate was N = 900 min^?1; while the other one was based on constant dissolved oxygen concentrations, C _DO = 5, 10, 15, 20 and 40 % in the fermentation broth, by using predetermined exponential glucose feeding with μ _o = 0.15 h^?1. The highest cell concentration was obtained as 44 g L^?1 at t = 9 h of the glucose fed-batch phase at C _DO = 20 % operation while the highest volumetric and specific enzyme activities were obtained as 4440 U L^?1 and 126 U g^?1 cell, respectively at C _DO = 15 % operation. Investigation of specific enzyme activities revealed that keeping C _DO at 15 % was more advantageous with an expense of relatively higher by-product formation and lower specific cell growth rate. For this strategy, the highest oxygen transfer coefficient and oxygen uptake rate were K _L a = 0.045 s^?1 and OUR = 8.91 mmol m^?3 s^?1, respectively.     

A Polarization Filter Based on Photonic Crystal Fiber with Symmetry Around Gold-Coated Holes

We propose a modified design for a photonic crystal fiber (PCF) polarization filter based on surface plasmon resonance (SPR). The air holes are arrayed in diamond lattices, and the diameter of the holes around the gold-coated holes are different that can separate the refractive index of the x-polarization and y-polarization second order surface plasmon polariton (SPP) modes. The influences of structural parameters of the photonic crystal fiber (PCF) on the filter characteristics are studied using the finite element method (FEM). Great changes have taken place in the results of numerical simulation by changing the thickness of the gold film and air hole diameter. Simulation results show that the resonance wavelength is communication wavelength 1550 mm, the loss of the y-polarization mode is 43,126.7 dB/m. When the length of the fiber is 500 μm, extinction ratio is more than 20 dB at the communication wavelength, and bandwidth achieve to 190 nm. It is an important property of PCF polarization filter in production.     

<Emphasis Type="Italic">In vitro</Emphasis> growth profile and comparative leaf anatomy of the C<Subscript>3</Subscript>–C<Subscript>4</Subscript> intermediate plant <Emphasis Type="Italic">Mollugo nudicaulis</Emphasis> Lam.

Mollugo nudicaulis Lam., commonly known as John’s folly or naked-stem carpetweed, is an ephemeral species of tropical regions. The plant is ideal to study the eco-physiological adaptations of C₃–C₄ intermediate plants. In the present report, in vitro growth profiling of the plant and comparative leaf anatomy under in vitro and ex vitro conditions were studied. In vitro propagation of the plant was carried out on Murashige and Skoog (MS) basal medium augmented with additives and solidified with 0.8% (w/v) agar-agar or 0.16% (w/v) Phytagel?. The concentration of plant growth regulators (PGRs) in the basal medium was optimized for callus induction, callus proliferation, shoot regeneration, and in vitro rooting. The optimum callus induction was obtained from M. nudicaulis seedling hypocotyls. The highest regeneration induction of about 88% or nearly 41 shoots with about 142 leaves per culture vessel was observed from friable callus on MS basal medium solidified with Phytagel? and containing 4.44 μM 6-benzylaminopurine, 4.65 μM kinetin, 2.69 μM naphthaleneacetic acid, and 0.91 μM thidiazuron. In leaf anatomy, differences related to photosynthetic tissue organization were observed in leaves of in vitro and ex vitro plants, which indicated that changes in the environment affected the anatomy of subsequent leaves in plants. This is the first report of an efficient micropropagation protocol for M. nudicaulis, using an indirect organogenesis method. Efforts were made to optimize the concentrations of various PGRs and organic compounds for in vitro growth of regenerated shoots.     

Cold-Set Gelation of Commercial Soy Protein Isolate: Effects of the Incorporation of Locust Bean Gum and Solid Lipid Microparticles on the Properties of Gels

This study aimed to evaluate the ability of commercial soy protein isolate (SPI) to form cold-set gels under different pHs (5–11), pre-heating temperatures (60 °C, 80 °C), CaCl₂ (0–15 mM) and SPI (5–15%, w/v) concentrations, and also select a formulation for the investigation of the effects of incorporating locust bean gum (LBG) (0–0.3%, w/v) and solid lipid microparticles (SLM) on gels rheological and microstructural properties. Gels were evaluated in terms of visual aspect, water-holding capacity, microstructure (using confocal laser scanning microscopy and cryo-scanning electronic microscopy) and rheological properties. SPI showed higher solubilities at pHs 7 (32.0%), 9 (51.6%) and 11 (100%). Self-supported gels were obtained under several conditions at alkaline pHs. At pH 7, only systems pre-heated to 80 °C with 15% (w/v) SPI and 10 or 15 mM CaCl₂ gave self-supported gels. At neutral pH, samples showed relative structural instability, which was minimized with LBG incorporation. Formulations G_SPI (pH 7, preheated to 80 °C, 15% (w/v) SPI, 10 mM CaCl₂) and G_MIX (pH 7, preheated to 80 °C, 15% (w/v) SPI, 0.2% (w/v) LBG, 15 mM CaCl₂) were selected for emulsion-filled gels (EFG) production. Power law parameters (K′, K″), calculated from frequency sweep results, revealed that non-filled G_MIX (K′: 472.1; K″: 77.6) was stronger than G_SPI (K′: 170.4; K″: 33.6). Besides, G_MIX showed microphase separation. SLM stabilized with Tween 80-Span 80 were active fillers in EFG, altering microstructures and increasing G’, G” and the Young’s modulus (1.8 to 2.1 kPa for G_SPI and 1.4 to 2.2 kPa for G_MIX).     

Tunable Plasmonic Absorber Based on TiN-Nanosphere Liquid Crystal Hybrid in Visible and Near-Infrared Regions

In this paper, a tunable plasmonic absorber based on TiN-nanosphere/liquid crystal (LC) nanocomposite in visible and near-infrared regions is proposed. TiN-nanosphere/LC nanocomposite is a combination of titanium nitride (TiN) nanospheres dispersed in a host of LC and plays the main role in post fabrication tunability. The proposed absorber has three more than 90% absorption peaks and the absorption tunability of about 76 nm. It is shown that TiN-nanospheres are able to support localized surface plasmon resonance (LSPR). The Maxwell-Garnett theory is utilized to approximate the permittivity of the composite structure. Also, the effect of geometric parameters on the absorption is studied. Moreover, a single sheet of graphene is utilized to compensate the decrement of the absorption caused by the geometric parameters.     

Simulation of Some Plasmonic Biosensors for Detection of Hemoglobin Concentration in Human Blood

Three recently published plasmonic biosensors based on a birefringent solid-core or a partial-solid-core microstructured optical fiber are simulated for detection of hemoglobin concentration in human blood. For a larger value of the number of holes n _h but for the same value of the gold radius, the resonance spectral width and the difference between maximal amplitude sensitivity and resonant wavelengths are decreased, when the refractive index of the analyte is n _a = 1.357. Also, the loss and maximum of the amplitude sensitivity are increased in the same conditions. At the resonant wavelength λ = 0.6496 μm for the devices with n _h = 14, 17, and 35 holes and n _a = 1.357, the hemoglobin concentration is close to the mean value (157.5 g/l) of a man.     

A Polarization Filter Based on a Novel Photonic Crystal Fiber with a Gold-Coated Air Hole by Using Surface Plasmon Resonance

A novel design of a polarization filter based on photonic crystal fiber (PCF) is proposed in this paper. With the introduction of a gold-coated air hole, the resonance strength is much stronger in y-polarized direction than in x-polarized direction at some particular wavelengths, which is due to the metal surface plasmon effects. At the wavelength of 1.31 μm, the loss of y-polarized mode is 2138.34 dB/cm while the loss is very low in x polarization. Furthermore, the loss peak can be flexibly adjusted from the wavelength of 1.26 to 1.56 μm by changing the thickness of a gold layer, and the loss in y polarization can be kept above 1200 dB/cm. The significant loss in y polarization makes this PCF a good candidate for developing a polarization filter with high performance.     

<Emphasis Type="Italic">Halomonas heilongjiangensis</Emphasis> sp. nov., a novel moderately halophilic bacterium isolated from saline and alkaline soil

A moderately halophilic bacterium, designated strain 9-2^T, was isolated from saline and alkaline soil collected in Lindian county, Heilongjiang province, China. The strain was observed to be strictly aerobic, Gram-negative, rod-shaped, oxidase-positive, catalase-positive and motile. It was found to require NaCl for growth and to grow at NaCl concentrations of 0.5–14 % (w/v) (optimum, 7–10 %, w/v), at temperatures of 10–45 °C (optimum 25–30 °C) and at pH 5.0–10.0 (optimum pH 8.0). Phylogenetic analysis based on 16S rRNA gene sequences revealed that strain 9-2^T is a member of the genus Halomonas and is closely related to Halomonas desiderata DSM 9502^T (96.68 %), Halomonas campaniensis DSM 1293^T (96.46 %), Halomonas ventosae DSM 15911^T (96.27 %) and Halomonas kenyensis DSM 17331^T (96.27 %). The DNA–DNA hybridization value was 38.9 ± 0.66 % between the novel isolate 9-2^T and H. desiderata DSM 9502^T. The predominant ubiquinones were identified as Q9 (75.1 %) and Q8 (24.9 %). The major fatty acids were identified as C_16:0 (22.0 %), Summed feature 8 (C_18:1 ω6c/C_18:1 ω7c, 19.6 %), Summed feature 3 (C_16:1 ω6c/C_16:1 ω7c, 12.6 %), C_12:0 3-OH (12.0 %) and C_10:0 (11.7 %). The DNA G+C content was determined to be 69.7 mol%. On the basis of the evidence presented in this study, strain 9-2^T is considered to represent a novel species of the genus Halomonas, for which the name Halomonas heilongjiangensis sp. nov. is proposed. The type strain is 9-2^T (=DSM 26881^T = CGMCC 1.12467^T).     

Application of a Plasmonic Biosensor for Detection of Human Blood Groups

A recently published plasmonic biosensor based on birefringent solid-core microstructured optical fiber is applied for the detection of human blood groups. The birefringent behavior is obtained by removing five central air holes of a two-ring hexagonal lattice of holes in a gold-covered silica fiber with the blood layer surrounding the fiber. The sensing performance of two resonant modes (I based on a phase matching point and II based on a loss matching point) are analyzed. For an increase of the refractive index from 1.3768 (human blood group A) to 1.3796 (human blood group O), the resonance spectral width δλ _0.5 is decreased from 26.8 to 25.8 nm for the core mode I and δλ _0.5 is increased from 28.3 to 33.2 nm for the core mode II. In addition, the amplitude sensitivity S _A is increased from 329.7 to 372.2 RIU^?1 for the core mode I and S _A is decreased from 298.2 to 283.7 RIU^?1 for the core mode II. The average value (26.20 nm for core mode I and 31.07 nm for core mode II) of δλ _0.5 from the human blood groups A, B, and O for our plasmonic biosensor is smaller in comparison with a recently published average value (39.10 nm) of the full width at half maximum (FWHM). Our biosensor can be calibrated for a glycerol-water solution by using the linear dependence between the refractive index n _a and the mass fraction w of the solutes.     

<Emphasis Type="Italic">Paradevosia shaoguanensis</Emphasis> gen. nov., sp. nov., Isolated from a Coking Wastewater

A Gram staining negative, rod-shaped, aerobic bacterial strain J5-3^T with a single polar flagellum was isolated from coking wastewater collected from Shaoguan, Guangdong, China. It was motile and capable of optimal growth at pH 6–8, 30 °C, and 0–2 % (w/v) NaCl. Its predominant fatty acids were 11-methyl C_18:1 ω7c (29.2 %), C_16:0 (20.6 %), C_19:0 cyclo ω8c (18.2 %), C_18:0 (11.0 %), and C_18:1 ω7c/C_18:1 ω6c (10.9 %) when grown on trypticase soy agar. The major polar lipids were diphosphatidylglycerol, phosphatidylglycerol, two unknown glycolipids (GL1, GL2), and two unknown phospholipid (PL1, PL2). The predominant ubiquinone was Q-10, and the genome DNA G+C content was 61.7 mol %. Phylogenetic analysis based on the 16S rRNA gene sequences indicated that strain J5-3^T belonged to the family Hyphomicrobiaceae in Alphaproteobacteria. It shared the 16S rRNA gene sequence similarities of 93.8–96.1 % with the genus Devosia, 94.5–94.8 % with the genus Pelagibacterium, and <92.0 % with all the other type strains in family Hyphomicrobiaceae. It can be distinguished from the closest phylogenetic neighbors based on several phenotypic and genotypic features, including α-galactosidase activity, tetracycline susceptibility, major fatty acid composition, polar lipid profile, DNA gyrase B subunit (gyrB) gene sequence, and random-amplified polymorphic DNA profile. Therefore, we consider strain J5-3^T to represent a novel species of a novel genus within the family Hyphomicrobiaceae, for which the name Paradevosia shaoguanensis gen. nov., sp. nov. is proposed. The type strain of Paradevosia shaoguanensis is J5-3^T (=CGMCC 1.12430^T =LMG 27409^T).     

Tuning the Optical and Rheological Properties of Fullerene C<Subscript>60</Subscript>/Poly (Vinyl Pyrrolidone) Nanofluids via Inclusion of Nanogold

In this article, development of nanogold (NG) containing fullerene C₆₀ nanofluids (NFs) with poly (vinyl pyrrolidone) PVP polymer in water via a wet chemical route is reported and studied their rheo-optical properties. An inclusion of NG into a C₆₀:PVP nanofluid thus results in a gold (Au) surface plasmon resonance (SPR) enhanced π?→?π* C₆₀ (sp²) electron transition over 250–450 nm of absorption spectrum in water. Evolution of a broad Au-SPR band in the 450–750 nm region signifies that a controlled Au³⁺?→?Au reduction reaction had occurred on it and was carried in C₆₀:PVP NFs. The average maximum wavelength value has thus varied along with a molar extinction coefficient in a function of the Au-uploads and shape and size of the flocculates in the resulting Au:C₆₀-PVP NFs. A systematic rheological study performed on the Au:C₆₀-PVP NFs in water by varying the NG content up to 85.0 μM reveals a non-Newtonian behavior with an enhanced yield stress is a signature of Bingham flow. NG of different shapes serves as filler in C₆₀:PVP NFs so as it adapts tailored shear viscosity. The shear viscosity relaxes slowly to the base value on increasing the shear rate from 10 to 100 s^?1 as it leads to breaking up of soft Au:C₆₀-PVP assemblies into a fine structures. Synthesis of Au:C₆₀-PVP NFs with various Au-contents could be potential nanostructure hybrid composite materials for development of photovoltaic nanodevices.     

Nutrient allocation and photochemical responses of <Emphasis Type="Italic">Populus</Emphasis> × <Emphasis Type="Italic">canadensis</Emphasis> ‘Neva’ to nitrogen fertilization and exogenous <Emphasis Type="Italic">Rhizophagus irregularis</Emphasis> inoculation

Arbuscular mycorrhizal fungi (AMF) can promote plant growth performance, but their effectiveness varies depending on soil nitrogen (N) availability. To clarify the effectiveness of exogenous AMF along an N-fertilization gradient (0, 2, 10, 20, and 30 mM), the impacts of exogenous Rhizophagus irregularis and N on the growth, photochemical activity, and nutritional status of Populus?×?canadensis ‘Neva’ in natural soil were evaluated in a pot experiment. The results showed that the 10 mM N level was the optimal fertilization regime with the highest promotion effect on plant growth and the maximum quantum yield of photosystem II (PSII) (F_v/F_m). Excess N (20 and 30 mM) fertilization reduced the actual quantum yield of PSII (ФPSII) and the F_v/F_m of the plants. Regardless of the N availability, inoculated plants exhibited greater F_v/F_m values than did non-inoculated plants. The biomass of inoculated plants was significantly higher compared with the control under low N levels (0 and 2 mM). Under high N levels, inoculated plants showed significant increases in ФPSII. Moreover, the nutrient imbalance of plants inoculated with exogenous R. irregularis was eased by increasing P, Fe, Mn and Cu uptake in roots and higher P, Ca, Mg, Fe, Mn and Zn concentrations in leaves. Moreover, the F_v/F_m and ФPSII exhibited positive correlations with P, Ca, Mg and Zn concentrations in leaves. In conclusion, inoculation with exogenous R. irregularis can benefit plant fitness by improving the photochemical capacity and nutrient composition of poplar under different N levels.