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Abnormal expression of miRNAs always occurs in solid tumors. Thus, it is critical to sensitively and selectively detect such biomarkers for the diagnosis and prognosis of diseases. Here, we report a biosensing scheme for the determination of miRNA with triple signal amplification based on target-triggered cyclic duplex specific nuclease digestion and bridge DNA-gold nanoparticles. Electrochemical signals are recorded to present initial levels of miRNA. This method is ultrasensitive with a wide linear range of 10[sup -17] to 10[sup -11] M. The limit of detection is down to 6.8 aM. Moreover, the overexpression of miR-21 is confirmed in lung cancer patients by the proposed method, which is in good accordance with qRT-PCR results. In addition, the developed biosensor does not need a reverse transcription process or any thermal cycling processes. Its performance satisfies the requirement for convenient, rapid, sensitive, and specific early diagnosis of cancers. Therefore, it may have great potential utility in the near future. [ABSTRACT FROM AUTHOR]

Transition-metal phosphides have recently been identified as low-cost and efficient electrocatalysts that are highly active for the hydrogen evolution reaction. Unfortunately, to achieve a controlled phosphidation of nonprecious metals toward a desired nanostructure of metal phosphides, the synthetic processes usually turned complicated, high-cost, and even dangerous due to the reaction chemistry related to different phosphorus sources. It becomes even more challenging when considering the integration of those active metal phosphides with the structural engineering of their conductive matrix toward a favorable architecture for optimized catalytic performance. Herein, we identified that the biomass itself could act as an effective synthetic platform for the construction of supported metal phosphides by recovering its inner phosphorus upon reacting with transition-metals ions, forming well-dispersed, highly active nanoparticles of metal phosphides incorporated in the nanoporous carbon matrix, which promised high catalytic activity in the hydrogen evolution reaction. Our synthetic protocol not only provides a simple and effective strategy for the construction of a large variety of highly active nanoparticles of metal phosphides but also envisions new perspectives on an integrated utilization of the essential ingredients, particularly phosphorus, together with the innate architecture of the existing biomass for the creation of functional nanomaterials toward sustainable energy development. [ABSTRACT FROM AUTHOR]

The first catalytic asymmetric total synthesis of the heptacyclic alkaloid (-)-communesin F is described. A key step features an iridium-catalyzed asymmetric intermolecular cascade cyclization, constructing the lower N,N-aminal-containing CDEF tetracyclic core in one step. Another notable element is the closure of final ring system (A ring) via a facile reduction of a twisted amide and concomitant cyclization activated by mesylation of N,O-hemiaminal intermediate. [ABSTRACT FROM AUTHOR]

We investigate the photophysicalproperty for 1,1,2,3,4,5-hexaphenylsilole(HPS) through combined quantum mechanical and molecular mechanical(QM/MM) simulations. Under the displaced harmonic oscillator approximationwith consideration of the Duschinsky rotation effect (DRE), the radiativeand nonradiative rates of the excited-state decay processes for HPSare calculated by using the analytical vibration correlation functionapproach coupled with first-principles calculations. The intermolecularpacking effect is incorporated through electrostatic interaction modeledby a force field. We find that from the gas phase to the solid state(i) the side phenyl ring at the 5-position becomes coplanar with thecentral silacycle, which increases the degree of conjugation, thusaccelerating the radiative decay process, and (ii) the rotation ofthe side phenyl ring at the 2-position is restricted, which blocksthe excited-state nonradiative decay channels. Such a synergetic effectlargely enhances the solid-state luminescence quantum efficiency throughreducing the nonradiative decay rate by about 4 orders of magnitude,leading to the radiative decay overwhelming the nonradiatvie decay.In addition, the calculated solid-phase absorption and emission opticalspectra of HPS are found to be in agreement with the experiment. [ABSTRACT FROM AUTHOR]

The effectiveness of a nonvegetated lab-scale subsurface flow constructed wetland for wastewater treatment had been evaluated with the feed ammonium concentration of ∼20-40 mg of NH[sub 4, sup +]-N L[sup -1] and a hydraulic retention time of ∼10 d. The present system had a nitrification zone plus a sulfur/limestone (S/L) autotrophic denitrification zone followed by an anaerobic polishing zone and was operated with and without aeration. The wetland had only 80% organics removal and no net nitrogen removal when there was no artificial aeration. However, almost 100% organics removal and ∼81-90% total inorganic nitrogen (TIN = NH[sub 4, sup +]-N + NO[sub 2, sup -]-N + NO[sub 3, sup -]-N) removal were achieved when the oxic zone of the system was aerated with compressed air. S/L autotrophic denitrification contributed 21-49% of total NO[sub 3, sup -]-N removal across the whole wetland and 50-95% across the S/L column. TIN and NH[sub 4, sup +]-N in the effluent were always <5.5 and < 0.7 mg L[sup -1], respectively, when the feed had NH[sub 4, sup +]-N ≤ 35 mg L[sup -1]. Sulfate removal of ∼53-69% was achieved in the anaerobic polishing zone. The position of the S/L column was changed (1.78, 2.24, and 2.69 m from the inlet), and no remarkable difference in nitrogen removal was observed. However, without the S/L column, TIN removal decreased to ∼74%, and the effluent NO[sub 3, sup -]-N increased about two times (9.13 mg of N L[sup -1]). The present study has demonstrated the possible use of S/L autotrophic denitrification for nitrate removal in a constructed wetland. [ABSTRACT FROM AUTHOR]

Presents a method for the fabrication of iridium oxide film hydrogen ion concentration microelectrodes. Fabrication of the microelectrode in a glass micropipet; Electrodeposition of iridium oxide over the platinized end; Response time of the microelectrode.

Evaluates the use of microelectrodes to measure pH and oxidation-reduction potential in munitions-contaminated soils. Variation in pH values in vegetated and unvegetated soils; Normalization of redox potentials; Variation in redox potentials.

Provides information on a study that determined a procedure to fabricate reliable redox potential microelectrodes. Steps in fabricating redox potential microelectrodes; Four standard solutions used to check the redox potential microelectrodes; Application of the procedure; Discussion of the study.

Focuses on the development of an introductory ion-exchange chelating fiber with aminophosphonic and dithiocarbamate groups which are based on polyacrylonitrile for the preconcentration of rare earth elements (REEs) in seawater prior to their determination. Function of the inductively coupled plasma mass spectrometry; Application of the fiber; Synthesizing of the hydrazine-modified polyacrylonitrile fiber.

Colloidal particles in a water–lutidine (WL) binaryliquidmixture experience temperature-dependent attraction close to the mixture’sdemixing temperature. This temperature-tunable interaction can bepotentially harnessed to assemble colloids and grow colloidal crystals.In this article, for the first time a novel attractive force gradientmethod is presented to fabricate high-quality, single-domain colloidalcrystals. The well-controlled attractive force gradient here arisesfrom a temperature gradient in the WL mixture. The nucleation of colloidalcrystals in such a WL mixture preferably occurs in the high-temperatureregion because of the stronger attraction there. Crystallization propagatesfrom the high-temperature region to the low-temperature region ina well-controlled way. The growth of the colloidal crystal is characterizedin detail by Voronoi construction, the pair correlation function,and the orientational order parameter. It is found that the numberof crystal-like particles increases with time, and a single-domain2D colloidal crystal can be produced. The mechanism of the defect-freecrystallization process is discussed on the basis of an analogy tocluster beam deposition methods. This study demonstrates an efficientand robust way to prepare colloidal crystals with little to no defects,being suitable for applications such as colloidal lithography andthe fabrication of perfect 3D colloidal crystals. [ABSTRACT FROM AUTHOR]

Ag2O/g-C3N4composites synthesizedin this study were applied in the photocatalytic degradation of phenolunder UV- and visible-light irradiation. X-ray diffraction, Fouriertransform infrared spectroscopy, X-ray photoelectron spectroscopy,and transmission electron microscopy analysis demonstrated that Ag2O nanoparticles were well distributed on the surface of g-C3N4, and the heterostructure of Ag2O/g-C3N4was formed. Compared with pure g-C3N4and Ag2O, the Ag2O/g-C3N4composite (8:1) displayed much higher photocatalyticactivities in phenol degradation under UV- and visible-light irradiation.The degradation rate constant of 8:1 was 0.069 min–1under visible light, which was almost 230 and 2.1 times more thanthat of pure g-C3N4and Ag2O, respectively.Moreover, the formation of a certain amount of Ag0on thesurface of Ag2O under illumination contributed to the highstability of Ag2O/g-C3N4photocatalysts.It was also found that photogenerated holes during the photocatalyticprocess played the predominant role in phenol degradation. The improvedphotochemical reactivities were attributed to the formation of theheterostructure between Ag2O and g-C3N4, the strong visible-light absorption, and the high separation efficiencyof photoinduced electron–hole pairs resulting from the highlydispersed Ag2O particles. [ABSTRACT FROM AUTHOR]

Amorphous calcium phosphate oftenforms as a precursor phase ina solution at sufficiently high supersaturation and pH, and then transformsto the thermodynamically stable hydroxyapatite. The chemical composition,structure, and property of the amorphous phase are dependent on thestructure of its composing clusters. Based on the results from themeasurements of in situ Ca K-edge X-ray near-edge structure and exsitu X-ray diffraction, as well as the concomitant pH change in thereaction process, here we propose an improved model for the structureof “Posner’s cluster” and identify the threetypes of reactions that lead to the formation of amorphous calciumphosphate and its subsequent transition to crystalline hydroxyapatite. [ABSTRACT FROM AUTHOR]

Microbial electrosynthesis, the conversion of carbon dioxide to organic molecules using electricity, has recently been demonstrated for acetogenic microorganisms, such as Sporomusa ovata. The energy for reduction of carbon dioxide originates from the hydrolysis of water on the anode, requiring a sufficiently low potential. Here we evaluate the use of sulfide as an electron source for microbial electrosynthesis. Abiotically oxidation of sulfide on the anode yields two electrons. The oxidation product, elemental sulfur, can be further oxidized to sulfate by Desulfobulbus propionicus, generating six additional electrons in the process. The eight electrons generated from the combined abiotic and biotic steps were used to reduce carbon dioxide to acetate on a graphite cathode by Sporomusa ovata at a rate of 24.8 mmol/day m2. Using a strain of Desulfuromonas as biocatalyst on the anode resulted in an acetate production rate of 49.9 mmol/day m2, with a Coulombic efficiency of over 90%. These results demonstrate that sulfide can serve effectively as an alternative electron donor for microbial electrosynthesis. [ABSTRACT FROM AUTHOR]

Calcium phosphate crystallization is of importance inmedicineand materials science, and aggregation frequently happens at its earlystage. Herein, we report a kinetic study of crystallization in particlesof aggregated nanocrystals of calcium phosphate by in situ synchrotronsmall-angle X-ray scattering. The particles were random fractal aggregates,having diameters of 20–60 nm and comprising structural unitsof 2.5 nm in dimension. With the application of a logistic model,the structural changes of the particles were characterized by thesuccessive developments of mass and surface fractal dimensions. Therate constant of mass fractal development was found to be 0.052 h–1, corresponding to the generation of crystalliteson the pre-existing seeds inside an aggregate. These newly formednanocrystals then detached from their seeds and fell into the voids.Afterward, the surface fractal structure developed at a rate of 0.11h–1, making the particle surface less rough. Duringthis period, a transition layer of 1.2-nm thickness emerged betweena particle and the surrounding solution. Our findings present an advancetoward understanding the crystallization in particles of aggregatednanocrystals and would be beneficial for preparing nanocrystals andrecognizing the roles of other substances (such as proteins and metals)in both biological and synthetic systems. [ABSTRACT FROM AUTHOR]

Supplements and growth promotants containing steroid hormones are routinely administered to beef cattle to improve feeding efficiency, reduce behavioral problems, and enhance production. As a result, beef cattle manure will contain both synthetic steroids as well as a range of endogenous steroids including androgens, estrogens, and progestogens. A two-year controlled study was conducted in which beef cattle were administered steroid hormones via subcutaneous implants and feed additives and the occurrence of 16 endogenous and synthetic steroid hormones and metabolites was evaluated in runoff from beef cattle feedlots and in manure and soil collected from feedlot surfaces. Samples were extracted and analyzed using liquid chromatography tandem mass spectrometryfor metabolites of the synthetic androgen trenbolone acetate, 17α-trenbolone, 17β-trenbolone, for the nonsteroidal semisynthetic estrogen agonist, α-zearalanol, and the synthetic progesterone melengesterol acetate, as well as a wide range of endogeneous estrogens, androgens, and fusarium metabolites. Synthetic steroids including trenbolone metabolites and melengestrol acetate were detected in fresh manure and in feedlot surface soils from cattle administered synthetic steroids at concentrations up to 55 ± 22 ng/g dry weight (dw) (17α-trenbolone) and 6.5 ± 0.4 ng/g dw (melengesterol acetate). Melengesterol acetate was detected in 6% of runoff samples from feedlots holding cattle administered synthetic steroids at concentrations ranging up to 115 ng/L. The presence of melengesterol acetate in runoff from beef cattle feeding operations has not been previously reported. Synthetic steroids were not detected in manure or runoff from control cattle. A wide range of endogenous hormones were detected in runoff and feedlot surface soils and manure from cattle given synthetic steroids and from control cattle, with no statistically significant differences in concentration. These results indicate that runoff from confined animal production facilities is of environmental and public health concern regardless of the use of growth promotants. [ABSTRACT FROM AUTHOR]