Synergetic effects of pyrrhotite and biochar on simultaneous removal of nitrate and phosphate in autotrophic denitrification system.

In the trend of upgrading wastewater treatment plants, developing advanced treatment technologies for more efficient nutrient removal is crucial. This study prepared a pyrrhotite-biochar composite (Fex Sy @BC) to investigate its potential for simultaneous removal of nitrate and phosphate under autotrophic denitrification conditions. X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), Fourier transform infrared spectroscopy (FTIR), and X-ray photoelectron spectroscopy (XPS) were used to characterize the novel composite of Fex Sy @BC, which exhibited 9.2 mg N/(L·d) NO3 - -N reduction rate, 97.3% N2 production, and 81.8 mmol N/(kg·d) NO3 - -N material load with small solid/liquid ratio (0.008). The NO3 - -N removal with Fex Sy @BC was 1.2-2.2 times higher than that with pure iron sulfides or biochar or their mixtures, whereas the Δn(S)/Δn(N) of Fex Sy @BC was the lowest (1.80). Moreover, the PO4 3- -P reduction rate of Fex Sy @BC reached 3.23 mg P/(L·d), as high as that of pure pyrite or pyrrhotite. Thiobacillus was the most dominant denitrifying bacterium. Fex Sy @BC exhibited great promise for enhancing nutrient removal from secondary effluent without additional carbon source. PRACTITIONER POINTS: FexSy@BC enhanced nitrate and phosphate removal simultaneously. First-order kinetics and Monod model were fitted for denitrification with FexSy@BC. FexSy@BC had smaller molar ratio of sulfate release to nitrate removal. Thiobacillus was the dominant bacterium in FexSy@BC autotrophic denitrification. Synergistic effects on nutrients removal existed between biochar and pyrrhotite.

Novel indoor positioning system based on ultra-wide bandwidth.

To tackle challenges such as interference and poor accuracy of indoor positioning systems, a novel scheme based on ultra-wide bandwidth (UWB) technology is proposed. First, we illustrate a distance measuring method between two UWB devices. Then, a Taylor series expansion algorithm is developed to detect coordinates of the mobile node using the location of anchor nodes and the distance between them. Simulation results show that the observation error under our strategy is within 15 cm, which is superior to existing algorithms. The final experimental data in the hardware system mainly composed of STM32 and DW1000 also confirms the performance of the proposed scheme.

The preliminary experiences of translocation renal cell carcinoma and literature review.

Xp11.2 translocation renal cell carcinoma (RCC) is rare and predominantly found in children and young adults. Because of the property of overexpressed transcription factor E3 (TFE3) fusion protein, immunohistochemical (IHC) staining with TFE3 antibody makes an excellent diagnostic tool. This study analyzed preliminary experiences of eight Xp11.2 translocation RCCs in our institution between 2007 and 2012. In four males and four females with a mean age of 28.4 years. Xp11.2 translocation RCCs were diagnosed. TFE3 IHC stain was positive in all tumor specimens. As the initial presentation, four patients suffered from abdominal pain, three cases had gross hematuria, and one case had hemoptysis caused by existing lung metastasis. The tumor was located in the right kidney (75%) with mean diameter of 5.85 ± 2.64 cm. Three cases (38%, 3/8) presented with lymph node metastasis at the time of diagnosis. In five cases (63%, 5/8), the initial diagnosis was Stage III and IV. Treatment included open surgery (one partial nephrectomy and five radical nephrectomies), cryoablation, immunotherapy, and target therapy. The mean follow-up time was 32 months. One patient died after 23.4 months of follow-up. The application of TFE3 IHC stain will improve the diagnostic accuracy for detecting XP11.2 translocation renal cell carcinoma. Surgery or cryoablation both had excellent prognosis in early stages. Although the disease is believed to be indolent, an increasingly aggressive clinical course should be kept in mind, especially for children and young adults.

Gold nanoparticle dimers for plasmon sensing.

In this study, gold nanoparticles (GNP) were stabilized for the first time as dimers by a conducting polymer (CP). The morphology of kissing particles was examined by high-resolution transmission electronic microscopy (HRTEM). The broad-band localized surface plasmon resonance (LSPR) tunable by solvent variation and molecular binding was demonstrated by UV-vis measurement. The sensitivity of the longitudinal LSPR to the surrounding media or the binding of a biomolecule was 6 times higher than that of the transversal LSPR. A homogeneous bioassay was directly developed from the highly stable GNP-CP dimers with LSPR as prober, and protein sensing with detection limit well below 100 ng/mL was achieved.

Label-free genosensor based on immobilized DNA hairpins on gold surface.

In this report, we demonstrate a label-free genosensor based on DNA hairpins coupled to gold coated sensor surfaces. The hairpin probes were labeled with a thiolated moiety for immobilization at the 5' end and with a fluorophore for signal transduction at the 3' end. In the absence of the complement, the fluorophore is quenched by energy transfer to the gold surface. Addition of the target sequence leads to the hairpin unfolding, and releases the fluorescent signal. This built-in property, using a gold film as both the immobilizing substrate and quenching agent, has the advantage of simplicity in design and ease of further integration. Our results showed that lengths of both the stem and the loop structures have significant effects on the sensor performance. Hybridization kinetics was investigated for various probe/target lengths and concentrations. An optimized hairpin probe gave a fluorescent signal increase of 39 folds after hybridization, which is much higher than the earlier reported results. A limit of detection (LOD) down to 0.3 nM for the complementary target DNA detection has been achieved. The developed sensor was further successfully applied for the detection of single-base mismatch targets, as well as for the direct detection of PCR products.

Fluorescence near gold nanoparticles for DNA sensing.

We investigated fluorescence quenching and enhancement near gold nanoparticles (GNP) of various sizes using fluorescently labeled hairpin DNA probes of different lengths. A closed hairpin caused intimate contact between the fluorophore and the gold, resulting in an efficient energy transfer (quenching). Upon hybridization with complementary DNA, the DNA probes were stretched yielding a strong increase in fluorescence signal. By carefully quantifying the amount of bound fluorescent probes and the GNP concentrations, we were able to determine the quenching and enhancement efficiencies. We also studied the size and distance dependence theoretically, using both FDTD simulations and the Gersten-Nitzan model and obtained a good agreement between experiments and theory. On the basis of experimental and theoretical studies, we report over 96.8% quenching efficiency for all particle sizes tested and a maximal signal increase of 1.23 after DNA hybridization. The described results also demonstrate the potential of gold nanoparticles for label free DNA sensing.

Fe(3)O(4)@Au/polyaniline multifunctional nanocomposites: their preparation and optical, electrical and magnetic properties.

Fe(3)O(4)@Au/polyaniline (PANI) nanocomposites were fabricated by in situ polymerization in the presence of mercaptocarboxylic acid. The mercaptocarboxylic acid was used to introduce hydrogen bonding and/or electrostatic interaction; it acts as a template in the formation of Fe(3)O(4)@Au/PANI nanorods. The morphology and structure of the resulting nanocomposites were analyzed by scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy, x-ray diffraction and x-ray energy dispersion spectroscopy (EDS). It was found that the nanocomposites were rod-like with an average diameter of 153 nm, and they exhibited a core-shell structure. A UV-visible spectrometer, semiconductor parameter analyzer and vibrating sample magnetometer (VSM) were used to characterize the optical, electrical and magnetic properties of the Fe(3)O(4)@Au/PANI nanocomposites. It was interesting to find that these properties are dependent on the molar ratio of Au to Fe(3)O(4) when the molar ratio of Fe(3)O(4)@Au to PANI is fixed. The magnetic property of the Fe(3)O(4)@Au/PANI nanocomposite is very close to superparamagnetic behavior.

Preparation of a nanowire-structured polyaniline composite and gas sensitivity studies.

To obtain organic nanowire sensors with high sensitivity and rapid response times, based on the inducement effect of surfactants during in situ polymerization, nanostructured polyaniline composites are obtained by using a chemical oxidation method by adding a small amount of surfactant. A casting method is employed on interdigitated carbon electrodes. The gas sensitivity to a series of chemical vapors is examined at room temperature. The results indicate that polyaniline with regular nanowire structure is obtained when succinic acid is added. The gas sensitivity and response rates of a film with nanowire structure are much better than those of conventional polyaniline films produced by means of organic solution spin coating methods. The film described in this work shows good selectivity to trimethylamine and other related gases and, the reaction being reversible with the use of high-purity nitrogen.