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Development of a rapid, highly sensitive and simple technique for screening polychlorinated biphenyls (PCBs) remains a challenge. In the present study, a novel fluorescent film chemosensor for PCBs based on fluorescence quenching was designed and synthesized. The fluorescent chemosensor is a hybrid organic–inorganic functionalized polysilsesquioxane film that is prepared from γ-(N,N-diphenylcarbamino)propyltriethoxysilane by sol–gel polymerization. The prepared fluorescent polysilsesquioxane film with diphenylamine as a fluorescent probe is sensitive to aqueous solutions of PCBs, including 2-chlorobiphenyl (PCB1), 2,2′-Dichlorobiphenyl (PCB4), 2,2′,5-trichlorobiphenyl (PCB18), 3,3′,4,4′-tetrachlorobiphenyl (PCB77) and 2,2′,4,5,5′-pentachlorobiphenyl (PCB101). PCBs efficiently quench the fluorescence of the chemosensor via a photo-induced electron transfer (PET) process. The fluorescence emission intensity of the polysilsesquioxane film sensor decreased steadily with a corresponding increase in PCBs. The detection limit of PCB77 was found to be 8.03 × 10 −7 M. The obtained results show that this fluorescent sensor has good thermal stability, high sensitivity and satisfactory reversibility in PCBs sensing.

Dioxins are a group of persistent organic pollutants which cause extreme harm to animals and human beings. There is great significance in developing fast and effective methods for enriching (capturing) and detecting dioxins. In this work, molecular dynamics (MD) simulations and quantum chemistry (QM) calculations have been used to study the inclusion complexation of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), the most toxic dioxin, with cucurbit[n]urils (CBn, n = 6, 7, and 8), a group of well-known host complexes applied in the study of host–guest interactions. The inclusion of TCDD with all three CBn hosts is found to be an energetically favorable process without remarkable energy barriers. In general, the host and guest form stable 1 : 1 complexes (TCDD–CBn), as indicated by calculated large complexation energies and small deformation energies of the host and guest. Moreover, the 1 : 2 host–guest complex (2TCDD–CB8) can be formed for CB8 due to its relatively larger cavity. The characteristic infrared (IR) and Raman peaks of TCDD are recognizable in the corresponding spectra of TCDD–CBn complexes. Based on the theoretical results, CBn are believed to be capable of including TCDD, and the TCDD in the inclusion complexes can be detected using both IR and Raman techniques. The results shown in this work are expected to be informative to the relevant experimental researchers.

Polybrominated diphenylethers (PBDEs), one of the most common brominated flame retardants, are toxic and persistent, generally detected by the chromatographic method. In this work, qualitative and quantitative detection of PBDEs were explored based on surface-enhanced Raman spectroscopy (SERS) technique using a portable Raman spectrometer. Alkanethiol modified silver nanoparticle aggregates were used as the substrate and PBDEs could be pre-concentrated close to the substrate surface through their hydrophobic interactions with alkanethiol. The effect of alkanethiols with different chain length on the SERS detection of PBDEs was evaluated. It was shown that 1-hexanethiol (HT) modified substrate has higher sensitivity, good stability and reusability. Qualitative and quantitative SERS detection of PBDEs in real sea water was accomplished, with the measured detection limits at 1.2×10(2) μg L(-1). These results illustrate SERS could be used as an effective method for the detection of PBDEs.

production. In order for most photoelectrons generated awayfrom the tips of the NWs to reach the catalyst sites, a longcharge diffusion distance is required. This requirementdictates that crystals of very high purity and high quality arerequired for high performance, leading to high costs ofmaterial preparation.From the perspective of device physics, the key torealizing full potentials held by the NW design is to ensureeffectivechargecollectionin theradialdirection.

A series of one-dimensional CdxZn(1−x)S semiconductor alloys were prepared via a hydrothermal method with the assistance of ethylenediamine at 180 °C for 12 h. The products were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, nitrogen adsorption/desorption and Fourier transform infrared techniques. With the value of x increased, the band gap of CdxZn(1−x)S semiconductor alloys gradually decreased indicating that catalysts were exchanged to visible-light response. Photocatalytic reduction results showed that Cd0.73Zn0.27S exhibited the highest photocatalytic activity toward photo production of aniline via nitrobenzene reduction under visible irradiation respectively. The reaction mechanism was also discussed.

The effective abatement of flue gas emissions, especially polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs), is one of the challenging issues in the field of environmental science currently. Imidazolium-based dicyanamide ionic liquids (ILs) were proposed to have potential in controlling the emissions of PCDD/Fs. However, the relevant mechanism at the molecular level still remains unclear. To address this subject, we here present a combined molecular dynamics (MD) simulation and quantum chemical (QM) study on the adsorption of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), the most toxic congener among PCDD/F family, by 1-butyl-3-methylimidazolium dicyanamide IL, a representative imidazolium dicyanoamide ILs, which were demonstrated to possess high capture capability for PCDD/Fs. The MD simulation results show that TCDD molecules can be effectively adsorbed on the IL surface to form a dense layer, but cannot enter the interior of the IL. The results of QM calculations show that the adsorption of TCDDs on the IL surface occurs via intra-molecular hydrogen bond interactions. The calculated interaction energy of the anion with TCDD molecule is two times more than that of the cation, implying that the IL anion dominates the interaction with TCDD molecules, while the cation plays a secondary role. Based on the calculated results, we propose that imidazolium dicyanamide IL films/membranes may be better materials than the corresponding bulk for capturing TCDD. The present theoretical results may be helpful to designing the functional ILs which effectively capture and concentrate PCDD/F compounds.

In this paper, 3,3′-diethyl-1,1′-oxydiethylenedicarbonyl bis(thiourea) (DEOECTU), was synthesized by phase transfer catalysis and then characterized by UV, elemental analysis, infrared spectra, mass spectrum, 1H NMR and TGA. DEOECTU properties, such as response to metal ions, adsorption on sulfide mineral surfaces, and hydrometallurgical performance as flotation collectors, were also investigated. The results indicated that DEOECTU reacted chemically with Cu2+ ions through its S and N atoms in the C(=S)–NH–C(=O) group to form a new chelate compound, but no reaction of DEOECTU with Zn2+, Pb2+, Fe3+ or Fe2+ ions was observed. The results of adsorption and flotation experiments demonstrated, that compared to pyrite, sphalerite and galena, DEOECTU exhibited a superior collecting power for chalcopyrite and might attach on chalcopyrite surface by chemisorption. The further theoretical analysis from Pearson’s HSAB view point briefly explained the experimental results of the selective response of DEOECTU to Cu2+ ions and chalcopyrite.

In this study, an imprinted silica matrix of pentachlorophenol (PCP) co-loaded with Fe(3)O(4) nanoparticles and ZnS:Mn(2+) quantum dots (QDs) was fabricated. The introduction of Fe(3)O(4) nanoparticles to the imprinted matrix provided an easy way to separate PCP under an external magnetic field. ZnS:Mn(2+) QDs offered a readout signal to monitor the amount of PCP bound to the imprinted matrix and evaluate the efficiency of imprinting. X-ray diffraction, transmission electron microscopy, Fourier transform infrared spectroscopy were used to characterize the imprinted matrix. The low angle X-ray diffraction and N(2) adsorption-desorption analysis indicated a periodic mesoporous structure. The as-synthesized imprinted matrix preferred to adsorb PCP rather than the other aromatic compounds like 2,4-dichlorophenoxy acetic acid, 2,4-dichlorophenol and phenol. The recoveries of spiked PCP in spring water and tap water with Fe(3)O(4)-ZnS:Mn(2+) co-loaded MIPs are 101% and 97%, respectively.

Surface oxidation states of ultrafine particulate matter can influence the proinflammatory responses and reactive oxygen species levels in tissue. Surface active species of vehicle-emission soot can serve as electron transfer-mediators in mitochondrion. Revealing the role of surface oxidation state in particles-proteins interaction will promote the understanding on metabolism and toxicity. Here, the surface oxidation state was modeled by nitro/amino ligands on nanoparticles, the interaction with blood proteins were evaluated by capillary electrophoresis quantitatively. The nitro shown larger affinity than amino. On the other hand, the affinity to hemoglobin is 103 times larger than that to BSA. Further, molecular docking indicated the difference of binding intensity were mainly determined by hydrophobic forces and hydrogen bonds. These will deepen the quantitative understanding of protein-nanoparticles interaction from the perspective of surface chemical state.

Solid phase microextraction-surface enhanced Raman spectroscopy (SPME–SERS), combining the pretreatment and determination functions, has been successfully used in environmental analysis. In this work, Au-coated ZnO nanorods were fabricated on stainless steel fiber as a self-cleaning SERS-active SPME fiber. The ZnO nanorods grown on stainless steel fiber were prepared via a simple hydrothermal approach. Then the obtained nanostructures were decorated with Au nanoparticles through ion-sputtering at room temperature. The obtained SERS-active SPME fiber is a reproducible sensitivity sensor. Taking p-aminothiophenol as the probe molecule, the RSD value of the SERS-active SPME fiber was 8.9%, indicating the fiber owned good uniformity. The qualitative and quantitative detection of crystal violet and malachite green was also achieved. The log–log plot of SERS intensity to crystal violet and malachite green concentration showed a good linear relationship. Meanwhile, this SERS-active SPME fiber can achieve self-cleaning owning to the excellent photocatalytic performance of ZnO nanorods. Crystal violet was still successfully detected even after five cycles, which indicated the high reproducibility of this SERS-active SPME fiber.

The effective enrichment and identification of lowly concentrated polychlorinated biphenyls (PCBs) in the environment is attracting much research attention due to human health concerns raised from their emissions. Cyclodextrins (CDs) are known to be capable to form inclusion complexes with a variety of organic molecules. The purpose of this study is to provide theoretical evidences whether CDs can form energetically stable inclusion complexes with PCBs through a host–guest interaction, and if so, whether infrared and Raman techniques are suitable for the detection of CD-modified PCBs. Focusing on a representative PCB molecule, 3,3′,4,4′,5-pentachlorobiphenyl (PCB126), we studied its molecular inclusion by β-CD (BCD) by performing molecular dynamics simulations and density functional theory calculations. Calculated results show that PCB126 and BCD preferentially form the stable 1:1 inclusion complex. The calculated IR spectra of the 1:1 inclusion complexes mainly present the spectra features of BCD and give only a slight indication for bands of the guest molecule. In contrast, the characteristic vibration modes of the guest molecule are remarkably prominent in the Raman spectra of the inclusion complexes. Based on the present results, we propose that BCD can potentially serve as a candidate for including PCB126 to form the stable 1:1 host–guest complex, and that Raman spectroscopy technology is expected to be suitable for the identification of the CD-modified PCBs, whereas IR spectroscopy is not feasible for such an application.

The addition of Bismuthiol II to the gold nanoparticles (AuNPs) solution led to the aggregation of AuNPs with a color change from red to blue. As a result, hot spots were formed and strong surface-enhanced Raman scattering (SERS) signal of Bismuthiol II was observed. However, the Bismuthiol II-induced aggregation of AuNPs could be reversed by Hg(2+) in the system, accompanied by a remarkable color change from blue to red. As evidenced by UV-vis and SERS spectroscopy, the variation in absorption band and SERS intensity was strongly dependent on the concentration of Hg(2+), suggesting a colorimetric and SERS dual-signal sensor for Hg(2+). The sensor had a high sensitivity, low detection limits of 2nM and 30nM could be achieved by UV-vis spectroscopy and by SERS spectroscopy, respectively. Other environmentally relevant metal ions did not interfere with the detection of Hg(2+). The method was successfully applied to detect Hg(2+) in water samples. It was simple, rapid and cost-effective without any modifying or labeling procedure.

Ordered dichloro-biphenylene-bridged silsesquioxanes are fabricated by interfacial polymerization at the aqueous/organic phase interface, which involves hydrogen bonding and aromatic π–π stacking interaction, which are responsible for the preferential orientation of the organic bridged units. The high-resolution transmission electronic microscopy images and wide angle X-ray powder diffraction patterns reveal the well-ordered features with lamellar spacings in the hybrid silsesquioxanes. Fluorescence spectra and molecular simulation verify the possibility of ordered structure formation. A general model is developed for the formation of ordered 3,3′-dichloro-biphenylene-bridged silsesquioxanes by interfacial polymerization. This method should offer a convenient avenue for the preparation of highly ordered hybrid network materials.

The rapid enrichment and detection of trace polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) are currently challenging issues in the field of environmental science. In this paper, by performing quantum chemistry (QM) calculations and molecular dynamics (MD) simulations, we studied the inclusion complexation of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), a representative PCDD molecule, with β-cyclodextrin (β-CD), one of the widely used compounds in supramolecular chemistry. The calculated results reveal that the stable inclusion complex can be formed in both the gas phase and solvent, which proposes that β-CD may serve as a potential substrate enriching TCDD. The calculated vibrational spectra indicate that the infrared (IR) and Raman spectroscopy may be suitable for the detection of β-CD-modified TCDD. The present theoretical results may be informative to environmental scientists who are devoting themselves to developing effective methods for detection and treatment of POPs.

In this paper, a simple and novel method for the determination of polychlorinated biphenyls (PCBs), using silver nanoparticles (AgNPs) as a resonance light scattering (RLS) probe, is proposed. Under optimized conditions, there existed linear relationships between the enhancing RLS intensity of the system and the concentrations of PCBs in the range 8.0 × 10(-8) -1.0 × 10(-6) g mL(-1) for 2,4,4'-trichlorbiphenyl (PCB28), 9.0 × 10(-8) -1.0 × 10(-6) g mL(-1) for 2,2',5,5'-tetrachlorbiphenyl (PCB52) and 4.0 × 10(-8) -1.0 × 10(-6) g mL(-1) for 3,3',4,4'-tetrachlorobiphenyl (PCB77). The corresponding detection limits (S/N = 3) were 2.6 × 10(-8) g mL(-1) for PCB28, 3.3 × 10(-8) g mL(-1) for PCB52 and 6.3 × 10(-9) g mL(-1) for PCB77, respectively. Finally, the mechanism of RLS enhancement was also studied. The results indicated that PCBs were adsorbed on the surface of AgNPs to form larger AgNP-PCB aggregates, resulting in the RLS enhancement of the system.

Lomefloxacin has been increasingly used in veterinary medicine to treat microbial infections. To avoid using a complicated instrumental method to detect lomefloxacin residue in food, a simple and convenient indirect competitive enzyme-linked immunosorbent assay method has been developed in this study. The antibody generated from immunogen of bovine serum albumin-lomefloxacin showed high sensitivity toward lomefloxacin with an IC50 value of 0.35 ppb in PBS buffer and was suitable to be used as a screening assay to detect lomefloxacin residue in food products. The ELISA (Enzyme-Linked ImmunoSorbant Assay) developed in this study was compared with a commercial ELISA kit and significant improvement was achieved in terms of sensitivity and specificity. The antibody prepared showed excellent specificity with certain cross-reactivity with only two drugs including norfloxacin (17.5%) and fleroxacin (8.8%) among commonly used (fluoro)quinolones. The assay measured drug residue in defatted milk spiked with lomeflox...

Hierarchical In 2 O 3 rod-like microbundles were fabricated via the Pluronic F127–(EO 106 PO 70 EO 106 –) assisted hydrothermal reaction followed by calcining the In(OH) 3 precursors. The results revealed that the In 2 O 3 microarchitectures were constructed with well-aligned one-dimensional (1D) single-crystalline nanorods with highly uniform morphologies and particular exposed facets. Structural analysis suggested that the In 2 O 3 nanorods were enclosed by {1 1 0} and {0 0 1} facets. The triblock copolymer acted as a structure-directing agent and played a key role in the formation of In(OH) 3 microbundles. The formation of the precursors In(OH) 3 microbundles was studied through contrastive experiments and computational simulation, which can be contributed to the soft-template-directed self-assembly mechanism. The gas sensing properties of the as-prepared In 2 O 3 microbundles were investigated. Compared to the samples prepared in the absence of F127, the In 2 O 3 microbundles exhibited a superior sensing performance toward 2-chloroethanol vapor, which can be explained by hierarchically ordered structures and exposed crystal surfaces.

The effective enrichment and identification of lowly concentrated polychlorinated biphenyls (PCBs) in the environment is attracting enormous research attention due to human health concerns. Cyclodextrins (CDs) are known to be capable of forming inclusion complexes with a variety of organic molecules. The purpose of this study is to provide theoretical evidence of whether CDs as host molecules can include the guest molecules PCBs to form stable host-guest inclusion complexes, and if so, whether the general infrared and Raman techniques are suitable for the direction of CD-modified PCBs. Focusing on a representative PCB molecule, 2,2',5,5'-tetrachlorobiphenyl (PCB52), we carried out density functional theory calculations and molecular dynamics (MD) simulations on its complexes with α-, β-, and γ-CDs with different host-guest stoichiometry ratios, including 1:1, 1:2, 2:1, and 2:2. On the basis of both the optimized geometries and calculated energy changes raised from encapsulating the guest molecule into the cavities of CDs, the CDs are believed to be suitable hosts for accommodating PCB52 guest molecules. The stability of inclusion complexes depends on both the type of CD and host-guest stoichiometry ratio. MD simulations give a clear picture of the scene on how the PCB52 molecule enters the cavity of β-CD. The vibrational analyses on the 1:1 complexes of CDs provide information for the spectral characterization of the inclusion complexes: Raman spectroscopy can deliver the characteristic bands of PCB52, whereas IR spectroscopy cannot uniquely assign them, implying that Raman spectroscopy is a useful technique for the identification of CD-modified PCBs. The present theoretical results are expected to provide guidance for the relevant experimental research.

A facile and reliable electrochemical technique at beta-cyclodextrin incorporated carbon nanotubes modified glassy carbon electrode (beta-CD/CNTs/GCE) was proposed for determination of pentachlorophenol (PCP). The electrochemical behavior of PCP at the beta-CD/CNTs/GCE was investigated by cyclic voltammetry and linear sweep voltammetry. The beta-CD/CNTs/GCE showed good analytical performance characteristics in electrocatalytic oxidation of PCP, compared with the simple carbon nanotube modified electrode (CNTs/GCE) and bare glassy carbon electrode (GCE). After accumulation for 5 min on beta-CD/CNTs/GCE, the peak current increased linearly with the concentration of PCP in the range from 8.0 x 10(-7) to 1.04 x 10(-5) mol/L. The detection limit was 4.0 x 10(-8) mol/L at 3 sigma level. The proposed electrode presented good repeatability for the determination of PCP in artificial wastewater, and the recovery was 97%-103%. This modified electrode combined the advantages of carbon nanotubes and supramolecular cyclodextrin, leading to new capabilities for electrochemical detection of PCP.

Cd1−xZnxS nanoparticles were prepared by a one-pot solvothermal process from Zn(CH3COO)2, Cd(CH3COO)2 and NaS2CNEt2·3H2O (sodium diethyldithiocarbamate, DDTC). The Cd1−xZnxS nanoparticles were characterized by X-ray powder diffraction, transmission electron microscope and high-resolution transmission electron microscope equipped with an energy-dispersive X-ray spectrometer. The absorption spectra of the Cd1−xZnxS nanoparticles can be tuned into visible region by modulating stoichiometric ratio between Zn and Cd. With the increase of Zn content, the Cd1−xZnxS nanoparticles showed an enhanced photocatalytic activity on degradation of 4-chlorophenol. The Cd1−xZnxS prepared under the optimal experimental condition (initial Zn/Cd = 3:1, 210 °C, 24 h, in ethanol) possessed the best photocatalytic activity. The conversion ratio could reach up to 84% after 12 h under irradiation of visible light for Cd1−xZnxS prepared in ethanol, which was obviously superior to those of products prepared in water. These results showed that both crystallinity and synthetic medium were responsible for the enhanced photocatalytic activity for 4-chlorophenol.

One-dimensional (1D) heterostructures of uniform CdS nanowires separately decorated with hematite (α-Fe2O3) nanoparticles or magnetite (Fe3O4) microspheres were successfully synthesized via a two-step solvothermal deposition method. Each CdS nanowire had a uniform diameter of 40−50 nm and a length ranging from several to several tens of micrometers. Quasicubic α-Fe2O3 nanoparticles, with edge lengths up to about 30 nm, and Fe3O4 microspheres, with diameters of about 200 nm, anchored on nanowires free from any surface pretreatment form 1D dimer-type CdS/α-Fe2O3 semiconductor heterostructures or CdS/Fe3O4 semiconductor magnetic functionally assembled heterostructures. It was also found that α-Fe2O3 nanoparticles with a smooth surface were well-crystallized, and Fe3O4 microspheres with a relatively rough surface showed a polycrystalline nature. The relationship between the crystal structures and effects of lattice mismatch on the formation of heterojunctions were systematically investigated. The magnetic and...

BACKGROUND: Danofloxacin is used widely as both a clinical medicine for humans and a veterinary drug in animal husbandry. In this study a polyclonal anti-danofloxacin antibody was prepared for the first time and a simple and rapid indirect competitive enzyme-linked immunosorbent assay (cELISA) method based on the antibody was developed to monitor danofloxacin residue in chicken liver. RESULTS: The prepared antibody showed high sensitivity, with an IC50 value of 2.0 ng mL−1 towards danofloxacin, and good specificity, with significant cross-reactivity only towards pefloxacin (22%) and fleroxacin (21%) among commonly used (fluoro)quinolones evaluated in the study. The developed cELISA test kit had a detection limit of 0.8 ng mL−1, and satisfactory results were obtained when it was applied to chicken liver spiked with various levels of danofloxacin. The cELISA test kit was also used to detect danofloxacin in chicken liver samples purchased from a local food market, and the results were confirmed by liquid chromatography/mass spectrometry. CONCLUSION: The anti-danofloxacin antibody prepared in this study exhibits excellent quality, with high sensitivity and good specificity. The cELISA test kit based on the antibody has a very low detection limit and is suitable for use as an efficient screening method to detect danofloxacin residue in foods and food products. Copyright © 2009 Society of Chemical Industry

One-dimensional (1D) CdS@ZnS core-shell nanocomposites were successfully synthesized via a two-step solvothermal method. Preformed CdS nanowires with a diameter of ca. 45 nm and a length up to several tens of micrometers were coated with a layer of ZnS shell by the reaction of zinc acetate and thiourea at 180 °C for 10 h. It was found that uniform ZnS shell was composed of ZnS nanoparticles with a diameter of ca. 4 nm, which anchored on the nanowires without any surface pretreatment. The 1D CdS@ZnS core-shell nanocomposites were confirmed by XRD, SEM, TEM, HR-TEM, ED, and EDS techniques. The optical properties and photocatalytic activities of the 1D CdS@ZnS core-shell nanocomposites towards methylene blue (MB) and 4-chlorophenol (4CP) under visible light (λ > 420 nm) were separately investigated. The results show that the ZnS shell can effectively passivate the surface electronic states of the CdS cores, which accounts for the enhanced photocatalytic activities of the 1D CdS@ZnS core-shell nanocomposites compared to that of the uncoated CdS nanowires.

An indirect competitive chemiluminescent enzyme-linked immunosorbent assay (CL-ELISA) for detection of gatifloxacin residue in milk was developed in this study. Compared with conventional colorimetric ELISA using the same antibody, the developed CL immunoassay shows a significant improvement in sensitivity and detectability with an IC50 of 0.4 ng mL−1 and a detection limit of 0.001 ng mL−1 and thus is suitable to be used as a highly sensitive screening method to detect and regulate illegal use of gatifloxacin in food and food products. The test kit was applied to detect milk samples spiked by gatifloxacin, and satisfactory results were obtained.

Preparation of 1D CdS-Ni semiconductor-magnetic nanocomposites was achieved by means of electroless plating of nickel nanoparticles on CdS nanowires. Preformed CdS nanowires with a diameter of ca. 45 nm, a length up to several tens of μm were magnetically functionalised by the hydrazine-induced reduction of nickel chloride in ethylene glycol at 140 °C. It was found that nickel nanoparticles with a diameter of ca. 80 nm anchored on the nanowires without any surface pretreatment. Furthermore, a conversion process was detected and confirmed, something which is favourable for the nonepitaxial growth of Ni nanoparticles on CdS nanowires. The products prepared thereof were characterised in detail by XRD, TEM, HR-TEM and EDS techniques. Magnetic property measurements show that the nanocomposites display ferromagnetic properties at room temperature.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)

A facile one-pot microwave irradiation reduction route has been developed for the synthesis of highly luminescent CdTe quantum dots using Na2TeO3 as the Te source in an aqueous environment. The synthesis parameters of this simple and rapid approach, including the reaction temperature and time, the pH of the reaction solution and the molar ratio of the 3-mercaptopropionic acid (MPA) stabilizer to Cd2+, have considerable influence on the particle size and photoluminescence quantum yield of the CdTe quantum dots. The photoluminescence quantum yield of CdTe quantum dots prepared using relatively short reaction times (10–40 min) reached 40%–60% (emission peaks at 550–640 nm). Furthermore, the resulting products could be used as fluorescent probes to detect Hg2+ ions in aqueous media. The response was linearly proportional to the concentration of Hg2+ ion in the range 8.0×10−9 mol/L to 2.0×10−6 mol/L with a detection limit of 2.7×10−9 mol/L.

We report on the synthesis of novel, unconventional beta-Ga(2)O(3) tubes via a Sn nanowire template process using thermal decomposition and oxidation of SnO and GaN powder mixtures. Distinctly different from any previously reported nano- and microtubes, the present beta-Ga(2)O(3) tubes display a flattened and thin belt-like (or ribbon-like) morphology. Each ribbon-shaped tube has a width of approximately 1-2 microm over its entire length, a length in the range of tens of micrometers, a thickness of approximately 100-150 nm, and a uniform inner diameter of 30-120 nm. The tubes were either partially or completely filled with Sn nanowires, forming Sn/Ga(2)O(3) metal-semiconductor nanowire heterostructures. A convergent electron beam generated in a transmission electron microscope is demonstrated to be an effective tool for delicate manipulation of encapsulated Sn nanowires. The Sn nanowires were gently cut apart (into two discrete fragments) and then completely separated and rejoined within Ga(2)O(3) ribbon-shaped tubes. These unconventional beta-Ga(2)O(3) tubes not only should enrich the well-established bank of nanostructured morphologies and extend the understanding of crystal growth at the nanoscale but also may have promise for the design of electron-beam-irradiation- or thermo-driven electrical switches.

Unique, highly crystalline, triangular BN nanoplates with a wide bandgap - which will ease their integration into nanoelectronic and photonic devices - are reported to be synthesized by reaction of NH4BF4 and NaNH2 with the assistance of metallic Ni. A thorough analysis of the morphological and structural characteristics of the nanoplates is presented. © 2004 IOP Publishing Ltd

Solid phase microextraction (SPME), a solvent free technique for sample preparation, has been successfully coupled with GC, GC-MS, and HPLC for environmental analysis. In this work, a method combining solid phase microextraction with surface enhanced Raman spectroscopy (SERS) is developed for detection of polycyclic aromatic hydrocarbons (PAHs). Silver nanoparticle aggregates were deposited on the Ag-Cu fibers via layer-by-layer deposition, which were modified with propanethiol (PTH). The SERS-active SPME fiber was immersed in water directly to extract PAHs and then detected using a portable Raman spectrometer. The pronounced valence vibration of the C-C bond at 1030 cm(-1) was chosen as an internal standard peak for the constant concentration of PTH. The RSD values of the stability and the uniformity of the SERS-active SPME fiber are 2.97% and 5.66%, respectively. A log-log plot of the normalized SERS intensity versus fluoranthene concentration showed a linear relationship (R(2) = 0.95). The detection limit was 7.56 × 10(-10) M and the recovery rate of water samples was in the range of 95% to 115%. The method can also be applied to detection of PAH mixtures, and each component of the mixtures can be distinguished by Raman characteristic peaks. The SERS-active SPME fiber could be further confirmed by GC-MS.

The authors' endeavors in recent years to synthesize novel inorganic semiconducting nanowires, to analyze their atomic structures using state-of-the-art electron microscopy facilities and techniques, and to evaluate electrical properties are highlighted. Along with a general survey of nanostructures prepared and thoroughly characterized in the laboratory, particular emphasis is placed on analysis of non-standard nanowires in the Si-ZnS and B-C-N inorganic systems. Si-ZnS biaxial nanowire heterojunctions are found to be n-type semiconductors, due primarily to a lower resistance Si-path. Fractal-like B-C-N nanofibers display high-resistivity I-V curves arising from enrichment of the nanostructure periphery by the insulating BN-rich phase, as revealed by spatially-resolved chemical mapping during energy-filtering electron microscopy.