A sensor is a tool used to directly measure the test compound (analyte) in a sample. Ideally, such a device is capable of continuous and reversible response and should not damage the sample. ...Nanosensor refers to a system in which at least one of the nanostructures is used to detect gases, chemicals, biological agents, electric fields, light, heat, etc. in its construction. The use of nanomaterials significantly increases the sensitivity of the system. In biosensors, the part of the system used to attach to the analyte and specifically detect it is a biological element (such as a DNA strand, antibody, enzyme, whole cell). The “Nano Biosensors” series reviews various types of biosensors and biochips (including an array of biosensors), emphasizing the role of nanostructures, developed for medical and biological applications. Nano Biosensors Electrochemical sensors are sensors that use the biological element as a diagnostic component and the electrode as a transducer. The use of nanostructures in these systems is usually done to fill the gap between the converter and the bioreceptor, which is at the nanoscale. Given the nature of the biomaterial detection process, electrochemical biosensors are divided into catalytic and propulsion. Common electrochemical techniques common in sensors include potentiometric, chronometry, voltammetry, impedance measurement, and field effect transistor (FET). Simultaneous use of the advantages of nanostructures and electrochemical techniques has led to the emergence of sensors with high sensitivity and decomposition power. The use of nanostructures in these sensors is usually done to fill the gap between the converter and the bioreceptor, which is at the nanoscale. Various types of nanostructures including nanoparticles, nanotubes and nanowires, nanopores, self-adhesive monolayers and nanocomposites can be used to improve the performance and efficiency of sensors in their structure. Simultaneous use of the advantages of nanostructures and electrochemical techniques has led to the emergence of sensors with high sensitivity and decomposition power.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
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•The synthesis of a novel xanthate derivative (HEIBX) and its application in the separation of chalcopyrite from pyrite.•The molecular behaviour of HEIBX and SIBX were compared by DFT ...calculation.•Properties of HEIBX were compared with properties of another surfactant SIBX.•HEIBX exhibited superior collector ability and selectivity for chalcopyrite against pyrite than SIBX.•HEIBX chemisorbed on the surface of chalcopyrite by formation of CuO and CuS bonds.
Separating chalcopyrite, an important copper-containing ore, from pyrite is an important mineral-processing objective. Herein, we report the synthesis of S-hydroxyethyl-O-isobutyl xanthate (HEIBX), a novel surfactant bearing both hydroxyl and thione groups, through the attachment of a hydroxyethyl group to sodium isobutyl xanthate (SIBX), and its first application as a flotation collector for the selective flotation-separation of chalcopyrite from pyrite. The flotation mechanism involving HEIBX and chalcopyrite or pyrite was investigated by DFT calculations, UV–vis spectroscopy, contact-angle and surface-tension measurements, flotation and zeta-potential experiments, as well as FTIR spectroscopy and XPS. Incorporation of the hydroxyethyl group was observed to increase the molecular properties of SIBX by increasing the number of active sites, arrangement density, selectivity and hydrophobicity, thereby improving its flotation performance. Chalcopyrite was separated from pyrite using 4 × 10−5 mol·L−1 HEIBX at pH ∼8.0. Furthermore, we found that the hydroxyl and thione functional groups adsorb onto the chalcopyrite surface though the formation of COCu and CSCu bonds.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Seagrass is the only one epigeal angiosperm completely growing under the seawater.Over 70 species of seagrasses belonging to 6 families and 13 genera are recorded in the world,while there are 22 ...species belonging to 4 families and 10 genera in China.The domestic experts of seagrass research in China have reach a consensus on unifying the Chinese scientific name of seagrass as “grass”instead of“algae”,on the occasion of “The 11th International Seagrass Biology Workshop” held in Sanya in November 2014.However,it is difficult to give the exact Chinese name in domestic articles when quoting non-Chinese seagrass species.For example,several Chinese names were observed for the same seagrass species;different species belong to the same genera have been considered as the same Chinese name;several species were expressed as Chinese general names with latin without providing the exact name.Meanwhile,“algae”names were found for their Chinese scientific name causing confusion.Thus,it is necessary to standardize the Chinese
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
Antibiotic resistance genes (ARGs) are increasingly a focus of concern because they pose a potential health risk. The Pearl River (PR) and Pearl River Estuary (PRE) show a distinct gradient in ...anthropogenic impacts, in particular associated with the use of antibiotics, from the river, to the estuary, and on to the coast. In this study, two surveys were conducted in the PR and PRE areas during the winter and summer of 2011, respectively. Seven tet genes consisting of efflux pump (tetA, tetC, and tetH) and ribosomal protection proteins (tetB, tetM, tetO, and tetW) were analyzed using the polymerase chain reaction (PCR) technique. The tet genes, with the exception of tetA and tetH, were widely detected in the PR and PRE environments. The tet genes exhibited a trend of an increase in total concentration and diversity with the degree of anthropogenic impacts from the river to the coast, indicating that riverine input was the main source of ARGs in the region. Significant correlations were observed between tet genes and antibiotic concentrations, as well as among different environmental compartments (water and sediments). The distribution patterns of tet genes were similar between the potential sources of pollution and the highly-impacted sites, but were significantly different between less-impacted sites and highly-impacted ones or pollution sources. The results suggest that ARGs and antibiotics may be released from identical sources, and transported in a similar manner in estuary/coastal environments close to sources of pollution.
The relative distribution pattern of tet genes was a good indicator in differentiating anthropogenic sources of ARGs from the regional background. Display omitted
► Relative distribution of tet genes was related to anthropogenic impacts. ► Transport from exogenous sources was the dominant process of ARGs in estuaries. ► ARGs can migrate among different environmental compartments. ► It is important to reduce/eliminate ARGs at pollution sources.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
In this paper, a Multi-Index Nonlinear Robust Adaptive Control (MINRAC) method was proposed for ultra-complex multi-input multi-output power systems with uncertain parameter factors and external ...disturbances. The controller designed by this method has excellent static and dynamic characteristics. Under the condition of the uncertainty of system parameters and external disturbance at the same time, the MINRAC method can ensure that the multiple indexes concerned by ultra-complex power systems can be controlled at their expected values. The simulation results showed that the control mechanism of MINRAC method was consistent in both single-machine infinite bus system and multi-machine interconnected coupling system. The output function chooses power angle, angular frequency and terminal voltage as constraints. When the system has parameter uncertainty and external interference, the uncertain parameter values are adjusted by adaptive control to force these indicators to tend to the given expected value. For three-phase short circuit, which is the most serious fault in power system, the use of multi index nonlinear robust controller can ensure that the system is stable in a wide range and has better dynamic performance.
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DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
•Selected antibiotics were widely distributed in the Pearl River Estuary (PRE), South China.•Antibiotics were primarily originated from wastewater discharges and aquacultural activities.•Seasonal ...variations in antibiotics were observed in surface and bottom water samples.•Environmental conditions affect antibiotics partitioning between water and sediment.
Antibiotics released into the aquatic environment play an important role in the spread of antibiotic resistance. In the Pearl River Estuary (PRE) and the coastal zone, the concentrations of antibiotics decreased from the Pearl River to the estuary, suggesting that antibiotics primarily originated from river tributaries and terrigenous sources. Within the PRE area, the concentrations of antibiotics in water were higher in the west coast than the east side, reflecting the high density of anthropogenic activities and hydraulic conditions along the west riverbank. Seasonal variations were also observed for most of detected antibiotics in water. The pseudo-partitioning coefficient of norfloxacin had a good correlation with the TOC content of sediments, as did erythromycin–H2O with the pH of water. The results suggest that environmental conditions can significantly affect the distribution of antibiotics between water and sediment.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
Theoretical formulation of droplet impact on elastic beams is relatively difficult, due to its transient, non-stationary, and elasto-capillarity nature. In this study, a numerical model is proposed ...based on the smoothed particle hydrodynamics (SPH) method to simulate the impact process of a droplet on elastic beams. Both of the liquid droplet and the elastic substrate are modeled by SPH, and this feature ensures that the fluid-solid interaction can be solved in a unified framework. In addition, the continuum surface force (CSF) method is adopted to simulate the surface tension effect on the droplet impact. Robustness, concision and validity of the model are validated by simulating a single water drop impact on elastic super-hydrophobic beams. Interesting phenomena of droplet bouncing and beam vibrations are reproduced following the experiment. These analyses may be beneficial to engineering new materials and new devices in such areas as fabrics, agriculture, petroleum, and micro/nano technology.
•A fully Lagrangian SPH-based model is developed for simulation of droplet impact on elastic surface.•The robustness of the model is ensured taking care on combining the advantages of different corrective techniques.•The continuous surface force method is implemented through accurately reconstructing the geometry of the droplet surface.•The springboard effect, beam vibration, and large deformation caused by water droplets are simulated.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
The first total synthesis of the akuammiline alkaloid (±)-vincorine (6) has been accomplished in about 1% overall yield in 31 steps. A concise assembly of the core 1,2-disubstituted ...1,2,3,4-tetrahydro-4a,9a-iminoethanocarbazole (1), a distinctive feature of akuammiline and strychnos alkaloids, was developed via a three-step one-pot cascade reaction consisting of copper-catalyzed intramolecular cyclopropanation, ring-opening, and ring closure. The construction of the last seven-membered E-ring in a rigid two-ring moiety (31, 45 to 47) through Heck coupling, Michael addition, π-allyl/Heck or π-allyl/Stille coupling failed, leading us to seek an alternative method. After successful addition of an acetate side chain on C15 of the cyclohexenyl ring (D-ring) in Boc-protected 35b by a Johnson−Claisen rearrangement and multistep modification of the functionality in the rearrangement product 33a, the E-ring formation was then realized for providing pentacyclic lactam 32 through intramolecular condensation of the acid group on the D-ring and the amine group on the C-ring with Mukaiyama’s reagent. An E-ethylidenyl group on the E-ring was stereoselectively added to afford lactam 56a through a two-step reaction of 32 consisting of aldol addition with acetaldehyde and cis-elimination of the resulting hydroxyl group. Final elaboration of 56a, including opening of the seven-membered E-ring, selective reduction of the α,β-unsaturated ester, and reclosure of the seven-membered E-ring completed the total synthesis of 6.
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IJS, KILJ, NUK, PNG, UL, UM
Most engineering structures with crack-like defects experience varying crack-tip loading during their service. This variation may result from combinations of varying applied loads and displacements ...and/or varying body force including residual stress. It is known that crack growth rates differ according to the
R-ratios when expressed via a single parameter, stress intensity factor range, Δ
K. Many methods have been proposed to incorporate the effect of the
R-ratio, including effective stress intensity factor range models based on crack closure and the two-parameter driving force model etc. However there are few clear statements about the choice of material constants for the calculation of crack growth lives under varying amplitude loading. This is a significant omission. In this paper, a simple crack growth rate equation has been proposed, which can condense the crack growth data under different
R-ratios to the curve corresponding to
R
=
0. Fatigue crack growth rate data for several materials taken from the literature, were analyzed using a new formulation. These data then cluster around the
R
=
0 crack growth rate curve. The result implies that crack growth rates for fatigue life calculation under different
R-ratios may be obtained directly from the constants corresponding to
R
=
0. Thus the most commonly tested crack growth rate constants corresponding to
R
=
0–0.1 are sufficient for fatigue crack growth calculation under different loading conditions.
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