Appearance Of New Peak Research Articles

Sustainable conversion of agro-wastes into useful adsorbents

Preparation and characterization of raw and activated carbon derived from three different selected agricultural wastes: kola nut pod raw and activated (KNPR and KNPA), bean husk raw and activated (BHR and BHA) and coconut husk raw and activated (CHR and CHA) were investigated, respectively. Influences of carbonization and acid activation on the activated carbon were investigated using SEM, FTIR, EDX, pHpzc and Boehm titration techniques, respectively. Carbonization was done at 350 °C for 2 h followed by activation with 0.3 M H3PO4 (ortho-phosphoric acid). Results obtained from SEM, FTIR, and EDX revealed that, carbonization followed by acid activation had a significant influence on morphology and elemental composition of the samples. SEM showed well-developed pores on the surface of the precursors after acid treatment, FTIR spectra revealed reduction, broadening, disappearance or appearance of new peaks after acid activation. EDX results showed highest percentage of carbon by atom respectively in the order BHA > KNPA > CHA respectively. The pHpzc was found to be 5.32, 4.57 and 3.69 for KNPA, BHA and CHA, respectively. Boehm titration result compliments that of pHpzc, indicating that the surfaces of the prepared adsorbents are predominantly acidic. This study promotes a sustainable innovative use of agro-wastes in the production of cheap and readily available activated carbons, thereby ensuring more affordable water and effluent treatment adsorbents.

Efficient decolorization of dye-containing wastewater using mycelial pellets formed of marine-derived Aspergillus niger

In order to improve the efficient decolorization of dye-containing water by biosorbent and understand the biosorption mechanism, the self-immobilization mycelial pellets were prepared using a marine-derived fungus Aspergillus niger ZJUBE-1, and an azo dye, Congo red was chosen as a model dye to investigate batch decolorization efficiency by pellets. The pellets as biosorbent showed strong salt and acid tolerance in biosorption process. The results for dye adsorption showed that the biosorption process fitted well with models of pseudo-second-order kinetic and Langmuir isotherm, with a maximum adsorption capacity of 263.2mg·g−1 mycelium. During 6 batches of continuous decolorization operation, the mycelial pellets could possess efficient decolorization abilities (>98.5%). The appearance of new peak in the UV–Vis spectral result indicated that the decolorization process may also contain biodegradation. The mechanism studies showed that efficient biosorption ability of pellets only relies on the active zone on the surface of the pellet, which can be enhanced by nutrition supplement or be shifted outward by a re-culture process.

Peroxynitrite-induced structural perturbations in human IgG: A physicochemical study

IgG is an important defence protein. To exhibit optimum function the molecule must maintain its native structure. Peroxynitrite is a potent oxidizing and nitrating agent produced in vivo under pathophysiological conditions. It can oxidize and/or nitrate various amino acids causing changes in the structure and function of proteins. Such proteins may be involved in the pathogenesis of many inflammatory diseases, including rheumatoid arthritis. In the present work, peroxynitrite-induced structural changes in IgG have been studied by UV–visible, fluorescence, CD, FT-IR, DLS spectroscopy and DSC as well as by SDS–PAGE. Peroxynitrite-modified IgG exhibited hyperchromicity at 280 nm, quenching of tryptophan fluorescence, increase in ANS fluorescence, loss of β-sheet, shift in the positions of amide I and amide II bands, appearance of new peak in FT-IR, attachment of nitro residues and increase in melting temperature, compared to native IgG. Furthermore, peroxynitrite-modified IgG exhibited an additional peak at 420 nm, quenching in tyrosine fluorescence and enhancement in dityrosine fluorescence compared to native IgG. Generation of nitrotyrosine, dityrosine and nitrotryptophan was also observed in peroxynitrite-modified IgG. Gross structural changes in IgG caused by peroxynitrite and observed in vitro may favour autoantibodies induction in vivo under similar conditions.

Fabrication of Ag2SeTe thin films by thermal evaporation

Semiconducting silver selenide telluride (Ag2SeTe) ternary thin films of different thicknesses were synthesised employing thermal evaporation. The variation in structure of the films with thickness was estimated using X-ray diffraction studies. The thin films of lower thickness were amorphous, and at higher thickness, they were polycrystalline in nature with orthorhombic structure. The film crystallinity increased with increase in thickness. Increase in thickness beyond 320 nm caused the appearance of new peaks with increased intensity. The structural studies on typical Ag2Se0·2Te0·8 system revealed that the stoichiometry of the bulk corresponded to that of the thin films. Micro-Raman spectra of the Ag2Se0·2Te0·8 thin films were recorded and analysed. The optical image of Ag2Se0·2Te0·8 thin films was also studied. The topography of the thin film was studied using atomic force microscopy. The results are presented.

Preparation of an activated carbon involving magnetic properties

Magnetic activated carbon composite (MAC) was successfully prepared from olive residues and hematite (Fe2O3/AC). MAC was prepared based on a wet impregnation method followed by carbonization, under different operating conditions. Specifically, two different MACs were prepared by altering the temperature ramp rate during the carbonization procedure (5 and 20 min/°C), designated here as MAC5 and MAC20, respectively. The increased magnetic capacity of the two MACs (as evidenced by the measured permanent magnetism of 30 mT), allowed their easy separation by utilizing a simple magnetic separation technology. The efficient impregnation of the iron oxide on the two MACs was confirmed by Fourier transform infrared spectroscopy (FT-IR), while scanning electron microscopy (SEM) was used to characterize the morphology of the composites. FT-IR measurements showed the appearance of new peaks, between 500 and 700 cm−1 which is evidence of the effective binding of iron onto AC (C/Fe). The SEM images offered an insight to the size and the distribution of the pores on the MAC, which appeared to be much better than the pure AC. The magnetic separation was examined through mass balances, before and after applying the magnetic field. The results showed that the magnetic efficiency of MAC5 is higher compared to that of MAC20. The magnetic properties of the produced MAC pave the way for their utilization in magnetic separation methods.

Localized Plasmon-Stimulated Nanochemistry of Graphene Oxide on a SERS Substrate.

In recent years, there has been remarkable progress in the reduction and functionalization of graphene oxide (GO) using nanoparticles and high-energy optical photons. Most of these reactions are carried out in solutions, whereas the local modification of GO on solid substrates still remains a challenge. In this work, we demonstrate the local reduction of GO and its further destruction, leading to the synthesis of polyaromatic hydrocarbons (PAHs) stimulated by localized surface plasmons (LSPs). The reduction of GO and the synthesis of PAHs have been carried out on a substrate designed for surface-enhanced Raman spectroscopy (SERS). We found that LSPs initiate the destruction of water molecules entrapped in the nanogaps between silver nanoparticles after the deposition of GO from the aqueous suspension. It was demonstrated that OH radicals, as a result of water decomposition, initiate the reduction of GO, leading to the synthesis of PAHs. The reactions have been observed in real time by using SERS. The measurement of current-voltage (I-V) characteristics through conductive atomic force microscopy (AFM), recorded in an LSP-stimulated area, have shown the increased electrical conductivity (more than ten times) compared with the conductivity of GO. The synthesis of new compounds in the LSP-stimulated area has been confirmed by the appearance of new peaks in the Raman spectra and nonlinear I-V characteristics typical for PAHs. We show that the used method allows the local modification of electrical properties of GO and controlled nanopattering of organic compounds on the surface.

Oxidative Coupling or Reductive Coupling? Effect of Surroundings on the Reaction Route of the Plasmonic Photocatalysis of Nitroaniline

Recent studies demonstrated that aromatic amines and aromatic nitro compounds could be converted to the corresponding azo species during surface-enhanced Raman experiments. It is very interesting to study the reaction mechanism for molecules that contain both an amino group and a nitro group, nitroaniline isomers. DFT calculations are applied to study the surface-enhanced Raman scattering and plasmonic photocatalysis of nitroaniline isomers on silver surfaces. The normal Raman and surface Raman spectra of nitroaniline isomers are first simulated and compared with experimental results. The calculated Raman spectra of o-nitroaniline (ONA), m-nitroaniline (MNA), and p-nitroaniline (PNA) correspond to their solid-state Raman spectra. However, the simulated surface Raman spectra of nitroaniline–silver complexes are significantly different from the experimental SERS spectra. According to the theoretical simulation, the appearance of new peaks in the SERS experiments of nitroaniline is attributed to the formatio...

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Interaction of thiazolyazoresorcinol (TAR) and thiazolyazocresol (TAC) with bovine serum albumin (BSA) and DNA base (adenine) were investigated by UV-visible, fluorescence, ATR - IR spectroscopy, cyclic voltammetry and molecular docking methods. The results studied by ATR-IR indicate that the secondary structures of the protein have been changed by the interaction of TAR and TAC with BSA. After the addition of TAR and TAC solution into BSA and adenine, the oxidative peak currents increased with the negatively shift of the peak potential and no appearance of new peak. The results from electrochemical studies suggested that the response of TAR and TAC at glassy carbon electrode was a diffuse controlled irreversible process. The results of molecular docking calculation clarify the binding mode and the binding sites which are in good accordance with the experiment results and hydrophobic force play a major role in the binding.

Improvements in the resolution of the foreign body reaction by the modulation of macrophage polarization towards an M2 phenotype at the tissue-implant interface by local release of IL-4 from layer by layer coated polypropylene meshes

Event Abstract Back to Event Improvements in the resolution of the foreign body reaction by the modulation of macrophage polarization towards an M2 phenotype at the tissue-implant interface by local release of IL-4 from layer by layer coated polypropylene meshes Daniel Hachim1, 2, Sam T. Lopresti1, 2, Deepa Mani1 and Bryan N. Brown1, 2, 3 1 University of Pittsburgh, Bioengineering, United States 2 University of Pittsburgh, McGowan Institute for Regenerative Medicine, United States 3 University of Pittsburgh, Department of Obstetrics, Gynecology and Reproductive Sciences, United States Introduction: Surgical mesh implantation is a common option for hernia repair and pelvic organ prolapse; however, associated with severe complications such as pain, organ perforation and mesh exposure[1]. Mesh complications are mostly due to host chronic foreign body reaction, performed by pro-inflammatory (M1) macrophages at the tissue implant interface[2]. On the other hand, pro-remodeling (M2) macrophages have been found to be important players in tissue remodeling[3]. Also, the M2:M1 ratio has been described to be a predictor of success of a biomaterial in-vivo[4]. It has been hypothesized that transient polarization of macrophages at the tissue-implant interface to an M2 phenotype will mitigate the foreign body reaction. Therefore, a nanometer thickness coating with the ability to provide local delivery of IL-4 (an in-vitro M2 polarizing cytokine) has been developed. Materials and Methods: Gynemesh® Polypropylene (PP) meshes were treated with radio frequency glow discharge (RFGD) to produce a negatively charged surface. To construct the coating, a layer-by-layer (LbL) procedure was performed using chitosan as polycation and dermatan sulfate as polyanion. Cycles were repeated with intermediate washing steps until desired number of layers. Loading of IL-4 was performed by prior incubation with dermatan sulfate. X-ray photoelectron spectroscopy (XPS), ATR-FTIR and alcian blue staining were used to characterize the coating. ELISA assays were used to evaluate the release of IL-4 at different time points. Also, a murine macrophage culture was used to corroborate the bioactivity of the released IL-4 by means of an arginase-1 immunolabeling and quantitative analysis. Finally, 1 cm2 pieces of mesh were implanted subcutaneously on the abdomen of female C57BL/6J mice and then sections of mesh-surrounding tissue were harvested at 7, 14 and 90 days for histology. Results and Discussion: Appearance of new peaks on the XPS and ATR-FTIR spectra but also stained meshes by alcian blue consistently confirmed the presence of a uniform, conformal coating made of both chitosan and dermatan sulfate. Similarly, confocal microscopy images of immunolabeled meshes showed a uniform loading of IL-4 through all the mesh surface (Figure 1A). ELISA assays showed that the amount and release time of IL-4 from coated meshes were dependent on the number of coating bilayers, but the power law dependence profile of release remained constant (Figure 1B). Additionally, higher expression of arginase-1 from macrophages exposed to IL-4 loaded meshes demonstrated M2 polarization and maintenance of IL4 bioactivity (Figure 1C). Interestingly, histological studies of mice implanted with IL-4 loaded meshes revealed less dense cellular inflammatory infiltrates around mesh fibers and a higher percentage of M2 macrophages compared to control meshes at 7 (Figure 2) and 14 days. Finally, mice implanted with IL-4 loaded meshes resulted in a diminished capsule formation at 90 days, as shown by Masson’s Trichrome (Figure 2) and Picro Sirius Red staining, compared to control meshes. Conclusions: Local release of IL-4 from coated polypropylene meshes is tunable and capable to polarize macrophages to an M2 phenotype both in-vitro and in-vivo, but also have shown to decrease inflammation and capsule formation in-vivo, suggesting improvements in the resolution the foreign body reaction against implanted mesh. This work was supported by the NIH grants K12HD043441 and R21GM107882. The content is solely the responsibility of the authors and does not necessarily represent the official views of the NIH.

Giant Raman Response to the Encapsulation of Sulfur in Narrow Diameter Single-Walled Carbon Nanotubes.

Encapsulation of sulfur in HiPCO-SWNTs leads to large changes in the Raman spectra with the appearance of new peaks at 319, 395, and 715 cm(-1) which originate from the sulfur species within the SWNTs, while the high frequency SWNT bands (ν > 1200 cm(-1)) are decreased in intensity. The encapsulated species also shifts the near-IR interband electronic transitions to lower energy by more than 10%. These effects seem to originate with the van der Waals interaction of the confined sulfur species with the walls of the SWNTs which are not expected to be significant in the case of the previously studied large diameter SWNTs. We suggest that sulfur in the small diameter SWNTs exists as a helical polymeric sulfur chain that enters the SWNT interior in the form of S2 ((3)Σ(g)(-)) molecules which undergo polymerization to linear diradicals.

Synthesis, characterization, X-ray crystal structure, electrochemical evaluation and anti-cancer studies of a mixed ligand Cu(II) complex of (E)-N′-((2-hydroxynaphthalen-1-yl)methylene)acetohydrazide

A ternary mixed ligand Cu(II) complex, [Cu(L)(Phen)], was prepared from the reaction of (E)-N′-((2-hydroxynaphthalen-1-yl)methylene)acetohydrazide [HL], Cu(NO3)2.3H2O and 1,10-Phenanthroline in 1:1:1 molar ratio. This complex was fully characterized using spectroscopic and physicochemical methods. The structure of the complex was determined by single crystal X-ray diffraction. The Cu(II) center is coordinated by two oxygen and one nitrogen donors of L2− and nitrogen atoms of the heterocyclic group. Electrochemical studies of the Cu(II) complex showed shifts in the ligand peaks as well as the appearance of new peaks after complexation. The electrochemical behavior of the Cu(II) complex was also studied using cyclic voltammetry. According to biochemical investigation (MCF-7 cells viability), anticancer activity of [Cu(L)(Phen)] was higher than those of Cu(NO3)2.3H2O, HL and 1,10-Phenanthroline.

Exploration of the role of modified titania nanoparticles with citric acid and vitamin C in improvement of thermal stability, optical property, and mechanical behavior of novel poly(vinyl chloride) nanocomposite films

In the present work, first the hydrophilic surface of titanium dioxide nanoparticles (TiO2 NPs) was modified with citric acid and then with vitamin C as bilayer surface modification for better compatibility with poly(vinyl chloride) (PVC) matrix. The process was accomplished under ultrasonic method as a fast, low‐cost, and green method. The modified TiO2 NPs were incorporated into the PVC matrix using the ultrasonic method. The resulting films (4, 8, and 12 wt%) were characterized by various techniques, including Fourier‐transform infrared spectroscopy, X‐ray diffraction, thermal gravimetric analysis, ultraviolet‐Visible analysis, and mechanical tensile test, and their morphology was investigated by field emission scanning electron microscopy and transmission electron microscopy. The appearance of new peaks (carbonyl group) and also its shift in the Fourier‐transform infrared spectrum of modified TiO2 NPs confirmed the presence of citric acid and vitamin C on the surface of the NPs. The resulting data of thermal gravimetric analysis showed improvement in thermal stability of the NC films. Also, strain and elongation of the samples increased in comparison with the pure PVC. J. VINYL ADDIT. TECHNOL., 23:E15–E24, 2017. © 2015 Society of Plastics Engineers

Numerical and experimental study of circular disc electromechanical impedance spectroscopy signature changes due to structural damage and sensor degradation

The article describes a study on the use of the electromechanical impedance spectroscopy method for crack-damage detection with piezoelectric wafer active sensors bonded to thin-walled structures. The study combines analytical, finite element method, and experimental methods. The specimens under consideration consisted of circular plates with circular piezoelectric wafer active sensors bonded at the center. Some of the plates were pristine, and others were damaged. The damage consists of simulated cracks (thin laser-machined slits) placed at various locations away from the center. For pristine plates, the electromechanical impedance spectroscopy spectrum was predicted with two numerical methods: (a) analytically using closed-form solutions and (b) Comsol 4.3 Multi-physics software using two-dimensional axisymmetric elements. The results were compared with experimental measurements performed with an HP 4194 impedance analyzer. This comparison allowed us to tune the model parameters. For plates with simulated cracks, the electromechanical impedance spectroscopy spectrum was predicted with three-dimensional finite element method models and then compared with experiments. Overall, the effect of crack damage on electromechanical impedance spectroscopy signature was found to consist of frequency shifts, peak splitting, and appearance of new peaks. These effects were predicted by the numerical models and confirmed by experiments. Modeshapes were also measured using a scanning laser Doppler vibrometer and compared with finite element method predictions. Interesting new modeshape features (local high-frequency modes) were observed near the crack. These features tend to explain some of the new peaks appearing in the electromechanical impedance spectroscopy spectrum. Further refining of the finite element method model was performed to capture variability effects associated with plate thickness, piezoelectric wafer active sensors thickness, adhesive layer thickness, and imperfect adhesive layer. The effect on the piezoelectric wafer active sensors asymmetrically placed electrodes and soldering points was also studied. It was found that these variations modify the electromechanical impedance spectroscopy signatures, but much less than the changes induced by the presence of the crack. Hence, it was concluded that the capability of the electromechanical impedance spectroscopy method to detect actual damage was not affected by these variations. A proper physics-based analysis and interpretation of the electromechanical impedance spectroscopy spectral changes are performed.

Role of peroxynitrite induced structural changes on H2B histone by physicochemical method

Histones are small highly conserved cationic proteins which bind DNA and remain confined in the nucleus. These histones are quite vulnerable to oxidizing and nitrating agents. Peroxynitrite is a powerful oxidant and nitrating agent present in the biological system. In this study, peroxynitrite-induced nitration and oxidation of H2B was assessed by various physicochemical techniques. The carbonyl content and dityrosine were markedly elevated in peroxynitrite-modified H2B histone as compared to the native histone. Cross-linking of H2B was evident on polyacrylamide gel electrophoresis. 3-Nitrotyrosine was present only in peroxynitrite-modified H2B revealed by HPLC. The results showed that peroxynitrite-mediated nitration and oxidation in H2B histone exhibited hyperchromicity, decrease of tyrosine fluorescence accompanied by increase in ANS-binding specific fluorescence, loss of β-sheet structure, appearance of new peak in FT-IR, increase in melting temperature and also loss of α-helix to produce a partially folded structure in comparison to intrinsically disordered structure of native H2B histone. We concluded that the H2B histone, a constituent of core histones, is highly sensitive to peroxynitrite and can adopt different structures under nitrosative and oxidative stress in order to protect the packaged DNA from the deleterious insult of peroxynitrite.

XPS analysis of the interface between AA2024‐T3/CF‐PPS friction spot joints

Friction spot joining (FSpJ) is an advanced, alternative technology suitable for joining metal‐composite overlap structures. In this paper, the principles of the FSpJ technique are briefly described. Furthermore, the influence of aluminum surface pretreatments (conversion coating and phosphoric acid anodizing) on the adhesion between aluminum alloy AA2024‐T3 and carbon‐fiber‐reinforced poly(phenylene sulfide) (CF‐PPS) friction spot joints was examined. X‐ray photoelectron spectroscopy (XPS) was used to investigate the changes in the chemical composition of the aluminum after surface pretreatments, as well as chemical bond formation at the interface between the aluminum and composite. The joints were mechanically loaded until failure, and the fracture surface of the joints were analyzed on the aluminum side. XPS results showed evidence of Al–C and Zr–C bond formation at the interface for the selected surface pretreatments in the course of the joining cycle. Chemical bond formation was confirmed through the analysis of C1s and Al2p regions in which the appearance of new peaks with different binding energies compared with the aluminum and composite were identified. Copyright © 2015 John Wiley & Sons, Ltd.

Bifunctional ionic liquid in conductive biopolymer based on chitosan for electrochemical devices application

Conductive polymer based on chitosan has been successfully prepared via solution casting technique with ionic liquid 1-butyl-3-methylimidazolium acetate ([Bmim][OAc]). [Bmim][OAc] plays two important roles in the conduction of chitosan: i) charge carrier and ii) plasticizer in this system. Appearance of new peaks and shifting of several characteristic peaks in the FTIR spectra signify the strong interactions between chitosan and [Bmim][OAc]. XRD diffractograms showed an increase in the amorphous region as the weight percentage (wt.%) of [Bmim][OAc] increases. SEM observations have proven the smoother surface morphology of the plasticized chitosan. The enhancement in the ionic conductivity (σ), is observed as the wt.% of [Bmim][OAc] increases. The highest σ achieved is (2.44±0.41)×10−3Scm−1 measured at ambient temperature (298K) and the corresponding activation energy is 0.2961eV. The temperature dependence of conductivity is Arrhenian in the studied temperature range and achieved σ of (7.60±0.62)×10−3Scm−1 at 70°C. The increase in the ionic conductivity is related to the decrease of glass transition temperature (Tg) as proven by the DSC analysis. High electrochemical stability of 3.4V was achieved of the highest conducting electrolyte by means of linear sweep voltammetry (LSV). Transference number measurement confirms that ions predominate the conduction of electrolyte with 0.75 ion transference number.

Phase transition and related electronic and optical properties of crystalline phenanthrene: An ab initio investigation

This investigation discusses a structural phase transition of organic crystalline phenanthrene and the resulting changes of its electronic and optical properties investigated by ab initio calculations based on density functional theory (DFT). The structure of phase I has been optimized then its electronic and optical properties have been calculated. Our computational results on phase I (at ambient pressure) get along well with the available experimental data.Calculating the electronic and optical properties of phase II are proceeded in the same way and the results, particulary Raman spectra, reveal a crystallographic phase transition indicated by abrupt changes in lattice constants which are accompanied by rearrangement of the molecules. This results in modifications of the electronic structure and optical response. For both phases the band dispersion of the valence and conduction bands are anisotropic, whereas the band splitting is strongly noticeable in phase II. By calculating the imaginary part of the dielectric function of phase II, we have found the appearance of new peaks at the lowest z-polarized absorption and about 30eV in all absorption components. Excitonic effects in the optical properties of phases I and II have been investigated by solving the Bethe–Salpeter equation (BSE) on the basis of the FPLAPW method. Phase II shows four main excitonic structures in the energy range below band gap, whereas phase I shows two. The excitonic structures in the optical spectra of phase II show a red shift in comparison to phase I. The calculated binding energies of spin-singlet excitons in phase II are larger than the ones in phase I.

Use of silane-functionalized graphene oxide in organic photovoltaic cells and organic light-emitting diodes.

Graphene oxide (GO) and silane-functionalized GO (sGO) sheets obtained through a simple sonication exfoliation method are employed as hole transport layers to improve the efficiency of organic photovoltaic (OPV) cells and organic light-emitting diodes (OLED). GO was functionalized using (3-glycidyl oxypropyl)trimethoxysilane (GPTMS) and triethoxymethylsilane (MTES). The appearance of new peaks in the Fourier-transform infrared spectra of the sGOs indicates the formation of Si-O-C, Si-O-Si, Si-H, and Si-O-C moieties, which provide evidence of the addition of silane to the GO surface. Furthermore, the appearance of Si-O-Si bonds in the synchrotron radiation photoelectron spectra (SRPES) of the MTES-sGO and GPTMS-sGO samples suggests that silane groups were effectively functionalized onto the GO sheets. An OPV cell with GO layers showed a lower performance with a power conversion efficiency (PCE) of 2.06%; in contrast, OPV cells based on GPTMS-sGO and MTES-sGO have PCE values of 3.00 and 3.08%, respectively. The OLED devices based on GPTMS-sGO and MTES-sGO showed a higher maximum luminance efficiency of 13.91 and 12.77 cd A(-1), respectively, than PEDOT:PSS-based devices (12.34 cd A(-1)). The SRPES results revealed that the work functions of GO, GPTMS-sGO, and MTES-sGO were 4.8, 4.9, and 5.0 eV, respectively. Therefore, the increase in the PCE value is attributed to improved band-gap alignment. It is thought that sGO could be used as an interfacial layer in OPV and OLED devices.

Polarographic determination of DNA based on its interaction with the phenanthroline-zinc(II) complex

By using the linear sweep voltammetric technique, a phenanthroline (Phen) and zinc(II) (Phen-Zn(II)) complex was used as the electrochemical probe for the determination of double-stranded (ds) DNA. In pH 9.0 Britton- -Robinson (B-R) buffer solution, Phen can interact with Zn(II) to form a stable electroactive [Phen-Zn(II)] complex, which had a sensitive second order derivative polarographic reductive peak at -1.300 V (vs. SCE). After the addition of dsDNA into a solution of Phen-Zn(II) complex, the reduction peak current decreased with a negative shift of the reduction peak potential and without the appearance of new peaks. The results showed that a new supramolecular complex was formed via interaction of the Phen-Zn(II) complex with dsDNA. The conditions of interaction and the electrochemical detection were carefully investigated. Under the optimum conditions, the decrease in the reduction peak current was directly proportional to the dsDNA concentration in the range of 0.4-18.0 mg L-1 with the linear regression equation: ?Ip?/nA = 349.48 + + 84.647(c/mg L-1) (n = 13, ? = 0.991) and a determination limit of 0.20 mg L-1 (3?). The relative standard deviation (RSD) for 10 parallel determinations of 10.0 mg L-1 dsDNA was found to be 2.03 %. The method was successfully applied to the detection of synthetic samples with satisfactory results.

A comparative study on the removal of Pb(II), Zn(II), Cd(II) and As(V) by natural, acid activated and calcinated halloysite

A comparative study on the removal of Pb(II), Zn(II), Cd(II) and As(V) by natural, acid activated and calcinated halloysite