Leaf-like Structure Research Articles

CHARACTERIZATION OF CARBON NITRIDE NANOPARTICLES PREPARED BY LASER ABLATION IN LIQUID FOR OPTOELECTRONIC APPLICATION

In this work, carbon nitride ( C 3 N 4) nanoparticles (NPs) were synthesized by pulse laser ablation of graphite in ammonium solution, and deposited on silicon substrates by spray. Fourier transform infrared spectroscopy (FTIR), UV-visible spectrophotometer and transmission electron microscopy (TEM) were used to study bonding, absorption, size and morphology of the produce NPs. The FTIR absorption peaks at 2121.6, 1631.7 and 1384 cm-1 stretching vibration bond, it is inferred for the C ≡ N , C = N and C – N , respectively. Bonds suggests the formation, C 3 N 4 NPs. UV absorption peaks coincide with the electronic transitions corresponding to the formation, C 3 N 4 NPs with 3.98 eV optical bandgap. The TEM show the aggregation of the C 3 N 4 NPs with size ranges from 4 to 83 nm, and also the leaf-like structure are shown in the structure of C 3 N 4 suspension. High performance rectifying C 3 N 4/ Si heterojunction with a rectifying ratio exceeding 345 at V = 5 V was obtained, with high photoresponsivity of 2.33 A/W at 600 nm.The results show that C 3 N 4 NPs on silicon substrates will act as very good candidates for making high efficiency photodiodes.

Morphology Control of Zeolitic Imidazolate Framework by Addition of Amino Acid l-Histidine

Abstract Amino acid l-histidine was introduced to the preparation of zeolitic imidazolate framework ZIF-L with controllable morphologies. Thick leaf-like particles (2–3 µm in length) with a thickness of about 1 µm were prepared, and their crystallinity decreased when less l-histidine was used. The decreased amount of water in the precursor solution resulted in a morphology change from a leaf-like structure to irregular microsized particles. The regulation of ZIF crystal morphology will lead to more versatile applications of ZIFs as functional materials in separation and adsorption.

Polydopamine-assisted synthesis of raspberry-like nanocomposite particles for superhydrophobic and superoleophilic surfaces

Inspired by nature, we combine the easy decoration of polydopamine with the attractive biomimetic silification to develop a facile synthetic route toward raspberry-like nanocomposite particles, and further lead to the superhydrophobic and superoleophilic surfaces by mimicking the lotus leaf surface structures in the usage of these particles. In this approach, monodisperse polystyrene (PS) particles are used as the template particles, and then, follows with a subsequent polydopamine (PDA) coating step through the self-polymerization of dopamine in a weakly alkaline aqueous environment (pH = 8.5). The obtained core–shell PS/PDA particles are used as the active substrates for the biomimetic silification under the ambient conditions, allowing a well-controlled synthesis of raspberry-like PS/SiO2 nanocomposite particles with a tunable surface roughness. Upon adjusting the concentration of silica precursor, the surface geometry and the coverage degree of silica nanoparticles of PS/PDA composite particles can be easily tailored. The whole procedure is carried out in a mild environment, no intricate instruments or toxic reagents are involved. In addition, these raspberry-like PS/SiO2 nanocomposite particles self-assemble onto the glass slides driven by capillary force during drying, forming a hierarchical dual-sized rough structure, which is analogous to the surface morphology of lotus leaf in nature. Making full use of this hierarchical surface, superhydrophobic and superoleophilic surfaces can be successfully achieved via a rational surface modification of this lotus leaf-like surface structure. The superhydrophobic performances can be readily adjusted by varying the scale ratio of the micro/nano surface structures.

Effect of annealing temperature on CrN microspheres synthesized by CAP technology

CrN microspheres were synthesized by using a cathodic arc plasma source system. The obtained samples were annealed in air at temperatures of 300–800 °C for 60 min. The influence of annealing temperature on the microstructure and surface morphology of the CrN microspheres was investigated. The CrN microspheres were characterized by means of scanning electron microscopy, transmission electron microscopy and X-ray diffraction analysis. The results show that the CrN nanoparticles arranged into leaf-like structures before annealing. With the rising of the annealing temperature, the size of CrN crystal nanoparticals became larger. When the annealing temperature exceeded the oxidation point (500 °C), the CrN was oxidized and the leaf-like structure was broken. With further increase of the annealing temperature (700 °C), the arrangement of CrN nanoparticles was changed from leaf-like structure to be discrete.

Surgical Treatment of Phyllodes Tumor of the Breast with the Trend

Objective Phyllodes tumors are composed of a benign epithelial component and a cellular spindle cell stroma that form a leaf-like structure. The purpose of this study was to define changes in patient characteristics, histopathologic parameters, and the outcome during two periods: before and after the introduction of core needle biopsy for preoperative diagnosis. Methods Records were reviewed of 170 patients with phyllodes tumors who were managed surgically. Patients treated from 1997 to 2004 (n = 101) were compared with patients treated from 2006 to 2013 (n = 69). Results The analysis of the two treatment periods revealed that the tumor size at diagnosis increased from 4.6 cm during the earlier period to 7.0 cm during the recent period (p < 0.05). The number of patients undergoing wide excision significantly increased during the recent period. Multivariate analysis revealed that a positive surgical margin was the only independent predictor of recurrence with an increased hazard of 4.8. Conclusion Wide excision with a clear margin is the first choice of current treatment for phyllodes tumors, even for malignant phyllodes tumors. However, this strategy does not further reduce local recurrence effectively, and core needle biopsy cannot be overstated in avoiding inappropriate initial surgery.

Simulating the growth process of aromatic polyamide layer by monomer concentration controlling method

Abstract With the wide distribution and gradual increase of TMC concentration ( C TMC ) from 1 × 10 −4 wt% to 2.5 × 10 −1 wt%, the main purpose of this work is to simulate the surface structure and properties of polyamide layer of reverse osmosis membranes at its different growth stage. The surface structure and properties of the resulted membranes were then characterized by atomic force microscopy (AFM), scanning electron microscope (SEM), attenuated total reflectance infrared (ATR-IR) spectroscopy, drop shape analysis system and electrokinetic analyzer. The structure growth of polyamide layer underwent in turn three different stages including spherical aggregator, leaf-like and typical ridge-valley structure. Spherical aggregator is the intrinsic structure in the inner layer of polyamide while leaf-like structure is transitional on the outmost polyamide layer. Furthermore, to clarify the effect of the structure change on the properties of polyamide layer, contact angle and zeta potential in the surface of polyamide layer were studied. Hydrophilic surface of polyamide layer is accessible at higher TMC concentration because of the presence of negative charged groups. Performances of the membranes were further measured with an emphasis on studying its structure–performance relationship during the growth process of polyamide layer.

One-pot green synthesis of high quantum yield oxygen-doped, nitrogen-rich, photoluminescent polymer carbon nanoribbons as an effective fluorescent sensing platform for sensitive and selective detection of silver(I) and mercury(II) ions.

This work reports on a facile, economical, and green preparative strategy toward water-soluble, fluorescent oxygen-doped, nitrogen-rich, photoluminescent polymer carbon nanoribbons (ONPCRs) with a quantum yield of approximately 25.61% by the hydrothermal process using uric acid as a carbon-nitrogen source for the first time. The as-prepared fluorescent ONPCRs showed paddy leaf-like structure with 80-160 nm length and highly efficient fluorescent quenching ability in the presence of mercury(II) (Hg(2+)) or silver (Ag(+)) ions due to the formed nonfluorescent metal complexes via robust Hg(2+)-O or Ag(+)-N interaction with the O and N of fluorescent ONPCRs, which allowed the analysis of Hg(2+) and Ag(+) ions in a very simple method. By employing this sensor, excellent linear relationships existed between the quenching degree of the ONPCRs and the concentrations of Hg(2+) and Ag(+) ions in the range of 2.0 nM to 60 μM and 5.0 nM to 80 μM, respectively. By using ethylenediaminetetraacetate and ammonia as the masking agent of Hg(2+) and Ag(+) ions, respectively, Hg(2+) or Ag(+) ions were exclusively detected in coexistence with Ag(+) or Hg(2+) ions with high sensitivity, and the detection limits as low as 0.68 and 1.73 nM (3σ) were achieved, respectively, which also provided a reusable detection method for Hg(2+) and Ag(+) ions. Therefore, the easily synthesized fluorescent ONPCRs may have great potential applications in the detection of Hg(2+) and Ag(+) ions for biological assay and environmental protection.

Macromol. Chem. Phys. 13/2014

Front Cover: Polarized optical microscopy images of poly(ethylene adiapate), a polyester, are shown in the cover image, before (left) and after (right) 24 hours of etching with methylamine (H3C–NH2). Upon etching, the originally ring-banded morphology of the polyester is disrupted into a maple leaf-like structure and chemically changed to an N,N′-dimethyldiamide linkage. Further details can be found in the article by G. Lugito, L.-Y. Wang, and E. M. Woo* on page 1297.

Spreading Dayflower Biology and Management in Turf

Spreading dayflower (Commelina diffusa) is a succulent annual that produces freely branched smooth stems. Leaves are broadly lance-shaped with closed sheaths. Sheaths are short with a few soft hairs on the upper margin. Flowers have three blue petals in a leaf-like structure open on the margins. Reproduction occurs via seed and stem fragments. This 2-page fact sheet was written by J. Bryan Unruh, Darcy E. P. Telenko, Barry J. Brecke, and Ramon Leon, and published by the UF Department of Environmental Horticulture, December 2013.

Superhydrophobic Surfaces Developed by Mimicking Hierarchical Surface Morphology of Lotus Leaf

The lotus plant is recognized as a ‘King plant’ among all the natural water repellent plants due to its excellent non-wettability. The superhydrophobic surfaces exhibiting the famous ‘Lotus Effect’, along with extremely high water contact angle (>150°) and low sliding angle (<10°), have been broadly investigated and extensively applied on variety of substrates for potential self-cleaning and anti-corrosive applications. Since 1997, especially after the exploration of the surface micro/nanostructure and chemical composition of the lotus leaves by the two German botanists Barthlott and Neinhuis, many kinds of superhydrophobic surfaces mimicking the lotus leaf-like structure have been widely reported in the literature. This review article briefly describes the different wetting properties of the natural superhydrophobic lotus leaves and also provides a comprehensive state-of-the-art discussion on the extensive research carried out in the field of artificial superhydrophobic surfaces which are developed by mimicking the lotus leaf-like dual scale micro/nanostructure. This review article could be beneficial for both novice researchers in this area as well as the scientists who are currently working on non-wettable, superhydrophobic surfaces.

Surfactant Assisted Synthesis of Copper Oxide (CuO) Leaf-like Nanostructures for Electrochemical Applications

Three different copper oxide (CuO) leaf-like nanostructures have been synthesised by micelles micro emulsion method using a surfactant of copper dodecyl sulphate (Cu(DS)2) by varying the concentration of sodium hydroxide (NaOH). This study was carried out to investigate the effect of NaOH concentration on the stability, crystalline domain and pseudocapacitance behaviour of the leaf-like nanostructures. The samples were characterized by X-ray diffraction (XRD), thermogravimetry analysis (TGA), Raman spectroscopy, Fourier-Transform Infrared (FTIR), scanning electron microscopy (SEM) and Transmission electron microscopy (TEM). It was observed that the crystalline domain size (12 nm-18 nm) and size distribution of the as-synthesized nanocrystals decreases with increasing concentration of NaOH. The interactions mechanism and formation of the leaf-like structure have been elucidated and correlated with various analytical techniques. The domain size and NaOH concentration tend to influence the charge transfer resistance.

Structural and optical properties of Gd2SiO5 prepared from hydrothermally synthesized powder

Cerium doped Gd2SiO5 (GSO) is an important scintillator material due to its high density and non-hygroscopic nature. GSO powder of uniform size and morphology synthesized by chemical method can be used as a source material to grow single crystals and to prepare transparent ceramics. In this work, rod-like Gd2SiO5 powder has been synthesized by hydrothermal reaction of precursors followed by a thermal treatment at 1400°C for 20h. Effect of various growth parameters on phase and morphology of the synthesized Gd2SiO5 has been investigated. The desired Gd2SiO5 phase is obtained for an appropriate concentration (∼0.5M) of the precipitating agent (NaOH) and molar ratio of precursors (Gd (NO3)3⋅6H2O: Si (OC2H5)4=2:1). A higher NaOH concentration and lower molar ratio of precursors (Gd:Si) result in the formation of additional phases. For the Gd:Si=1:1 ratio, a leaf-like structure of hexagonal Gd4.67 (SiO4)3O is obtained. Evolution of the desired phase GSO has been studied by the non-resonant Raman spectroscopy. Substitutional cerium doping up to 1at.% in the GSO initiates a preferred growth towards the [021] direction. The rod-shaped Ce doped GSO has an emission at 425nm for excitations at 280 and 345nm near room temperature.

Property enhancement of epoxy resin using a combination of amine-terminated butadiene–acrylonitrile copolymer and nanoclay

The present work investigates the effect of organomodified nanoclay (ZW1) and butadiene–acrylonitrile copolymer terminated with amine group (ATBN copolymer) on the properties of epoxy resin (EP). The impact strength (IS) and the critical stress intensity factor ( KC) values of EP containing 1% nanoclay increased approximately by 200% and 75%, respectively, in relation to neat EP. Moreover, hybrid composites containing 1% or 2% nanoclay and ATBN showed improved mechanical properties in relation with unmodified EP. The magnification and analysis of the Fourier-transform infrared spectra showed an increase in the peak height of 3338 cm-1 due to polymeric modifier incorporation. This finding might be explained by the reaction between modifier or hardener amine groups and the unreacted part of EP cured at room temperature. Hybrid composite containing 2% Nanobent ZW1 and 5% ATBN exhibited synergistic effect in terms of tensile adhesive strength toward composites with one modifier. Moreover, scanning electron micrographs showed more elongated and leaf-like structure for hybrid compositions, explaining the enhancement of IS and KC values of the tested composites.

Synthesis of hierarchical dendritic micro-nano structure CoxFe1−x alloy with tunable electromagnetic absorption performance

In this paper, both the leaf-like dendritic CoxFe1−x (x = 0.1, 0.3, 0.5 and 0.7) alloys and novel grain-like dendritic nanostructure Co0.9Fe0.1 alloy and e-Co were synthesized by an electric field-induced and electrochemical reduction method under over-polarization current. The formation of these two dendritic structures is not only attributed to the electric-field strength and ion concentration gradient, but also related to their crystalline structure. The trunks and branches of leaf-like dendritic bcc CoxFe1−x grow along three of the six equivalent directions. However, for grain-like dendritic hcp e-Co, their six branches grow along the six equivalent directions, and the trunks are oriented preferably along [0002] direction. The electromagnetic absorption (EMA) performance of leaf-like structure CoxFe1−x alloys are obviously enhanced with Co content increase from −21.7 dB for Co0.1Fe0.9 to −59.1 dB for Co0.5Fe0.5. Meanwhile, the response frequency of maximum reflection loss (RL) shifts to the higher band. In the case of grain-like dendritic Co0.9Fe0.1 alloy, it has the widest frequency band from 5 to 18 GHz with RL < −20 dB due to the mixed phase composition. We ascribe the enhancement of dendritic CoxFe1−x alloys' EMA performance to the different elemental compositions, crystalline structures, surface anisotropy and crystal defects, which contribute to enhancing the effective complementarities between dielectric loss and magnetic loss.

A novel β-nucleating agent for isotactic polypropylene

The nucleating ability of p-cyclohexylamide carboxybenzene (β-NA) towards isotactic polypropylene (iPP) was investigated by differential scanning calorimetry, X-ray diffraction, polarized optical microscopy and scanning electron microscopy. β-NA is identified to have dual nucleating ability for α-iPP and β-iPP under appropriate kinetic conditions. The formation of β-iPP is dependent on the content of β-NA. The content of β-phase can reach as high as 96.96% with the addition of only 0.05 wt% β-NA. Under non-isothermal crystallization the content of β-iPP increases with increasing cooling rate. The maximum β-crystal content is obtained at a cooling rate of 40 °C min–1. The supermolecular structure of the β-iPP is identified as a leaf-like transcrystalline structure with an ordered lamellae arrangement perpendicular to the special surface of β-NA. Under isothermal crystallization β-crystals can be formed in the temperature range 80–140 °C. The content of β-crystals reaches its maximum value at a crystallization temperature of 130 °C. © 2012 Society of Chemical Industry

Efficient Contaminant Removal by Bi2WO6 Films with Nanoleaflike Structures through a Photoelectrocatalytic Process

Bi2WO6 films with nanoleaflike structures, which are directly grown on a fluorinated tin oxide substrate, were first realized by a solvothermal method. Because of the peculiar leaflike structure, Bi2WO6 films exhibited excellent photocatalytic activity in the degradation of phenol, which is widely used but slowly degradable in the natural environment. The degradation of phenol could be further improved by a photoelectrocatalytic process, along with a sharp decrease of total organic carbon. According to the experimental results, a possible mechanism of the improved photoelectrocatalytic activity on the phenol removal was proposed. The stability of the directly grown leaflike Bi2WO6 film is excellent. As an immobilized film, it is easy to recycle for the next photoelectrocatalytic process. This advantage, combining the excellent stability and photoelectrocatalytic activity, makes it applicable in practical environmental purification.

Impact of CuO nanoleaves on MWCNTs/GCE nanocomposite film modified electrode for the electrochemical oxidation of folic acid

The salient features of the present work focus on the synthesis of CuO nanoleaves by alcoholic reduction of Cu(II) chloride in the presence of poly(diallyldimethylammonium chloride) (PDDA) for the application of folic acid oxidation in simulated body fluid environment. PDDA-assisted polyol process allows a conventional impregnation method for the formation of CuO with well-defined leaf-like structure. The structure and morphology of the CuO nanoleaves were characterized by Fourier-transform infrared (FT-IR) spectroscopy and X-ray diffraction (XRD) analysis. Field emission scanning electron microscope (FESEM) image confirms the formations of CuO with leaf-like morphology and branched side edges. The average size of the resultant CuO nanoleaves was calculated to be 400 nm in length and 150 nm in width. The electrochemical performance of the CuONs/MWCNTs/GCE nanocomposite modified electrode was characterized by cyclic voltammetric (CV) studies. The CuONs/MWCNTs/GCE nanocomposite modified electrode shows good electrochemical activity and it was also found that it possessed prominent electrocatalytic activity toward the oxidation of folic acid with as high a sensitivity as 3.35 μA/μM and a low detection limit (3σ) of 15.2 nM (S/N = 3). Besides, the CuO nanocomposite modified electrode lowers the over potential of folic acid oxidation than the unmodified electrodes.

An architectural model for the bladderwort Utricularia gibba (Lentibulariaceae)1

Members of the aquatic plant genus Utricularia have extremely modified vegetative morphology, which includes absence of roots and lack of a clear distinction between leaves and stems. In this study, the vegetative morphology, anatomy and growth pattern of Utricularia gibba (L.), a common species in the southern Florida Everglades, was analyzed to determine general developmental patterns and establish a basic model for growth of this species. Specimens were collected from different habitats in southern Florida during both the wet and dry seasons. Light and scanning electron microscopy were used to quantify anatomical and morphological characteristics. Utricularia gibba has a shoot apical meristem that produces repeating developmental units, each of which consists of a stolon bearing dichotomously branched leaf-like structure that supports the traps. These structures may subtend one or more axillary buds that can grow out to form additional stolons or inflorescences. The inflorescence produces aerial flowers, but also forms a modified stolon at its base that is covered with unique glandular papillae. Re-iteration of this model through branching creates the floating and benthic mats found in this species. The basic model can be expanded to other species of section Utricularia but not to all species of the genus.

One step preparation of polyaniline micro/nanohierarchical structures with superhydrophobicity

Polyaniline with a leaf-like hierarchical structure of 3μm in length, 2μm in width, 100nm in thickness and crisscrossed nanofibers decorated on the surface, was successfully prepared in one step polymerization of aniline in the presence of sodium heptafluorobutyrate. The synthesized polyaniline shows superhydrophobicity with a water contact angle of 151° due to the combination of the low surface tension of fluorinated chain and the rough micro/nanostructure. Chemical structure and composition of the resultant PANI were characterized by FTIR, UV–vis, XRD and XPS. The formation mechanism of the hierarchical structure was investigated by monitoring the morphology development with the polymerization time. This method is facile and applicable for the large scale fabrication. Many potential applications can be expected based on the superhydrophobic PANI micro/nanostructures.

Dose–response effects of an antimicrobial peptide, a cecropin hybrid, on growth performance, nutrient utilisation, bacterial counts in the digesta and intestinal morphology in broilers

The aim of the present study was to evaluate the feasibility of an antimicrobial peptide, cecropin A(1-11)-D(12-37)-Asn (CADN), as an alternative to antibiotic growth promoter (AGP) in poultry diets. A total of 1500 14-d-old indigenous male chickens (222 (sd 13) g) were randomly allocated to five groups with five replicate cages of sixty birds each, and fed ad libitum five grower diets and subsequently five finisher diets for 14 d each. The diets were made up by supplementing their basal diets with a CADN liquid sample (CADNL) at 0, 2, 4, 6 and 8 ml/kg, respectively. During the feeding period, a metabolic experiment was carried out to determine the apparent digestibility of diethyl ether extract, nitrogen retention and apparent metabolisable energy of the diet sample fed to each cage of chicks. At the end of the feeding experiment, one chick from each cage was killed for bacteriological, light microscopic and scanning electron microscopic examination of the intestinal villi. CADN had a negative linear, positive quadratic and negative linear effect on feed intake (F), weight gain (G) and feed:gain ratio (F:G), respectively, for the growers; it had a quadratic effect on F, G or F:G for the finishers; it increased nutrient utilisation for both growers and finishers; it decreased aerobic bacterial counts in both jejunal and caecal digesta in a dose-dependent manner; it enhanced intestinal villus heights in a dose-dependent manner and made the duodenum villi of the CADNL8 group at 42 d appear as a netted leaf-like structure. CADN is therefore a possible alternative to AGP in broiler feeds.