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• CeO 2 supports with various morphologies were synthesized & used in Ni-based catalyst. • The most abundant oxygen vacancy of CeO 2 -D can effectively improve catalytic activity. • Ni/CeO 2 -D exhibited the highest Ni dispersion and a superior TOF value of CH 4 in DRM. • The hierarchical dumbbell-like structure of catalyst can promote SMSI & CH 4 cracking. CeO 2 is widely used as Ni-based catalyst support in methane dry reforming (DRM), and the hierarchical structure of the ceria behaves a favorable effect on the performance of the catalyst. Ceria with different morphologies, including dumbbell (CeO 2 -D), bouquet (CeO 2 -B) and shuttle (CeO 2 -S) shapes, are hydrothermally prepared, and the effect of ceria shape on the catalytic performance of Ni/CeO 2 in DRM is investigated by a fixed-bed tubular reactor. The results indicate that Ni/CeO 2 -D demonstrates the best reaction conversions & TOF value, whose conversions of CH 4 & CO 2 can reach 92% & 87%, respectively. Furthermore, a series of characterization results (XPS, H 2 -TPR and Raman) confirm that the Ni/CeO 2 -D own the abundant oxygen vacancies and strong metal-support interaction, which promote the reactivity of CH 4 and CO 2 , resulting in its most prominent catalytic performance. Additionally, Ni/CeO 2 -D possesses other distinct advantages due to its hierarchical dumbbell-like structure confirmed by high Ni dispersion (H 2 -TPD), abundant surface oxygen (H 2 -TPR) and sufficient basic sites (CO 2 -TPD). [Display omitted] [ABSTRACT FROM AUTHOR]

Essential resources for plant growth are always heterogeneously distributed in natural ecosystems. Clonal plants can selectively place ramets in resource-rich patches to efficiently use heterogeneously distributed resources by altering spacer performance. Leymus secalinus , with a combination of phalanx and guerilla growth forms, can produce both spreading and clumping ramets. Previous studies have shown that nutrient availability decreases the proportion of spreading ramets. It was hypothesized that L. secalinus could place more ramets in resource-rich patches by producing more clumping ramets. To test this hypothesis, L. secalinus was grown under artificial conditions with heterogeneously distributed nutrients and light. Results showed that L. secalinus not only altered the spacer length and specific spacer biomass between spreading ramets, but also balanced the trade-off between phalanx and guerilla growth forms to place more ramets in resource-rich patches, even if the patches were very small. Such multiple adaptations by L. secalinus , together with a division of labor, may enable it to efficiently use heterogeneous resources in natural ecosystems and to subsequently change the localized environment. [ABSTRACT FROM AUTHOR]

Plant interactions greatly affect plant community structure. Dryland ecosystems are characterized by low amounts of unpredictable precipitation as well as by often having biological soil crusts (BSCs) on the soil surface. In dryland plant communities, plants interact mostly as they compete for water resources, and the direction and intensity of plant interaction varies as a function of the temporal fluctuation in water availability. Since BSCs influence water redistribution to some extent, a greenhouse experiment was conducted to test the hypothesis that the intensity and direction of plant interactions in a dryland plant community can be modified by BSCs. In the experiment, 14 combinations of four plant species (Artemisia ordosica, Artemisia sphaerocephala, Chloris virgata and Setaria viridis) were subjected to three levels of coverage of BSCs and three levels of water supply. The results show that: 1) BSCs affected plant interaction intensity for the four plant species: a 100% coverage of BSCs significantly reduced the intensity of competition between neighboring plants, while it was highest with a 50% coverage of BSCs in combination with the target species of A. sphaerocephala and C. virgata; 2) effects of the coverage of BSCs on plant interactions were modified by water regime when the target species were C. virgata and S. viridis; 3) plant interactions were species-specific. In conclusion, the percent coverage of BSCs affected plant interactions, and the effects were species-specific and could be modified by water regimes. Further studies should focus on effects of the coverage of BSCs on plant-soil hydrological processes. [ABSTRACT FROM AUTHOR]

Abstract: A new spectrophotometric method for the determination of nicotine in mixtures without pre-separation has been proposed. Nicotine could react with 2,4-dinitrophenol through a charge-transfer reaction to form a colored complex. The second-order data from the visible absorption spectra of the complex in a series of ethanol–water binary solvents with various water volume fractions could be expressed as the combination of two bilinear data matrices. With the bilinear model, the second-order spectra data of mixtures containing nicotine and other interferents could be analysed by using second-order calibration algorithms, and the determination of nicotine in the mixtures could be achieved. The algorithm used here was parallel factor analysis. The method has been successfully used to determine nicotine in tobacco samples with satisfactory results. [Copyright &y& Elsevier]

Aims Sand burial and precipitation play important roles in vegetation of inland deserts and desertified areas, and both are under strong influence of climate and land-use change. Sand deposition and precipitation both vary greatly in space and time, and different plant species, with diverse adaptations, occupy different niches along spatial gradients in the combination of sand and water availability dynamics. We hypothesized that species specificity in spatial and temporal niche occupation along such gradients is a mechanism for their co-existence and, thereby, a driver and stabilizer of biodiversity in dry, sandy areas. Location Ordos Plateau, China. Methods We conducted a 2-yr field experiment with factorial treatments of precipitation (control, slight enhancement, strong enhancement) and sand addition (control, medium addition, large addition). Plant cover of the six dominant species was followed over different seasons, as we expected different species to benefit from different treatments in different seasons and years with different weather regimes. Results Sand burial alone significantly affected plant cover of all six dominant species, while precipitation enhancement had no significant effect. Effects of sand burial on plant cover changed overall during the two hydrologically contrasting years. Our key finding was that there were multiple significant two- and three-way interactions between species, sand burial and precipitation enhancement on plant cover, while there were also multiple two- and three-way interactions involving species, sand burial or precipitation treatment with year and/or season. Conclusion Our results supported our hypothesis, i.e. the co-existence of species in a semi-arid sand dune can be explained from the different niches they occupy in terms of seasonal and year-to-year variation in precipitation in combination with sand deposition regime. The interactions of these drivers on plant cover with experimental enhancement of precipitation, mimicking a realistic scenario for this region, suggest that shifts in species composition are to be expected this century. More generally, our findings advance our understanding of what drives species co-existence and thereby biodiversity, now and in the future. [ABSTRACT FROM AUTHOR]

• Honeycomb-lantern-like CeO 2 support is prepared by template-free solvothermal method. • Synergistic effect between Ni and Co is used to further enhance the stability in DRM. • The kinetic equation based on Langmuir-Hinshelwood mechanism is accurately expressed. • Kinetic parameters of coke gasification are determined by the Wigner-Polanyi equation. Dry reforming of methane (DRM) is considered one of the most efficient methods for carbon utilization, as it can transform greenhouse gases (CH 4 and CO 2) into syngas (CO and H 2) which could be widely used in the production of high-value hydrocarbons. The synergistic effect between Ni and Co is leveraged to enhance the coke resistance and stability of Ni-based catalyst during the DRM process, building upon the surface spatial confinement provided by honeycomb-lantern-like CeO 2 support. The enhanced catalytic performance of Ni 0.9 Co 0.1 catalyst can be attributed primarily to the addition of cobalt, which facilitates CO 2 adsorption and activation, further promotes the Boudouard reaction and aids in the elimination of coke. This phenomenon is supported by evidence from CO 2 -TPD, XPS, SEM, TGA, XRD, and CO 2 -TPO analyses. Furthermore, the kinetics of Ni 0.9 Co 0.1 are examined using Power-Law (PL) and Langmuir-Hinshelwood (LH) mechanisms, obtaining the explicit equations for the rate constants (k and k r), reaction orders of the reactants (α and β), and adsorption equilibrium constants ( K CH 4 and K CO 2 ). The comparison of the predicted CH 4 consumption rates with the experimental rates suggests that the LH mechanism is notably more precise than PL mechanism for Ni 0.9 Co 0.1 catalyst. Moreover, the relevant kinetic parameters (the activation energy and pre-exponential factor), pertinent to coke gasification process for the spent Ni 0.9 Co 0.1 and Ni 1.0 , are determined and calculated through CO 2 -TPO characterization and the modified Wigner-Polanyi equation. [ABSTRACT FROM AUTHOR]

In present China, continuing to control PM2.5 (particulate matter < 2.5 μm) and preventing the rise of O3 are the most urgent environmental tasks in its air clean actions. Considering that NO2 is an important precursor of PM2.5 and O3, a comprehensive analysis around this pollutant was conducted based on the real-time-monitoring data from Jan 2018 to Mar 2019 in 11 prefecture-level cities in Shanxi Province of China. The results showed that the annual average concentration of NO2 in Shanxi prefecture-level cities is mainly distributed in the range of 28.84–48.93 μg/m3 with the values in five cities exceeding the Chinese Grade Ⅱ standard limit (40 μg/m3). The over-standard days were all concentrated in the heating season with a large pollution peak occurring in winter except in Lvliang, while four cities also had a small pollution peak in summer. High NO2 polluted areas were mainly concentrated in the central part of Shanxi, and trended on the whole from the southwest to the northeast (Lvliang/Linfen—Taiyuan/Jinzhong—Yangquan/Jinzhong), which was different from the spatial distribution of PM2.5 and O3. Lvliang was the hot spot of NO2 pollution in summer, while Taiyuan was the hot spot in winter. Concentration Weighted Trajectory (CWT) analysis indicated that central-north Shaanxi, central-south Shanxi, northern Henan, the south of Shijiazhuang and areas around Erdos in Inner Mongolia were important source areas of NO2 in Shanxi besides local emissions. Our findings are expected to provide valuable implications to policymakers in Shanxi of China to effectively abate the air pollution. [ABSTRACT FROM AUTHOR]

Abstract Sand burial is a common phenomenon in inland semi-arid and arid areas, affecting plant growth and even plant community structure. Precipitation regime, including the variation of precipitation intensity and frequency, also drives community structure and functions in such areas. However, few studies have focused on the combined effect of sand burial and changed precipitation regime on community function, specifically its role in carbon storage. A 2-yr field experiment with factorial treatments of precipitation (control, slight enhancement and strong enhancement) and sand addition (control and 5 cm sand addition) was conducted to test the responses of plant and soil carbon content in a semi-arid typical steppe in N China. Results showed that sand burial had no significant effect on plant carbon density, but significantly changed the allocation of plant carbon from aboveground to belowground; these responses differed among species and life forms in the community. Precipitation enhancement had no significant effects on plant carbon and its allocation, perhaps because effects of precipitation on plants are due more to precipitation frequency than to precipitation intensity per event. Sand burial and precipitation enhancement decreased soil carbon, especially soil organic carbon, and promoted soil carbon to be distributed deeper down the soil profile. These findings will help to understand how sand deposition affects plant and soil carbon storage and their allocation in plant communities under a changing precipitation regime, and more generally, to understand carbon storage dynamics in early-successional sandy ecosystems in the context of global change. Graphical abstract Unlabelled Image Highlights • Sand burial significantly changed the allocation of plant carbon from aboveground to belowground. • Precipitation enhancement had no significant effects on plant carbon and its allocation. • Sand burial and precipitation enhancement promoted soil carbon to be distributed deeper down the soil profile. [ABSTRACT FROM AUTHOR]

In this study, the direct synthesis conditions of dimethyl carbonate (DMC) from methanol and CO 2 were controlled under the dual supercritical conditions, whose temperature was higher than the maximal critical temperature of CO 2 and methanol (>239 ℃), and the partial pressure for each reactant was larger than its partial critical pressure (P CO2 > 7.4 MPa and P methanol > 8.1 MPa). A series of CeO 2 catalysts with different morphologies including traditional nanorod, amorphous and flower structures were synthesized by hydrothermal method. The prepared catalysts were characterized by the BET, XRD, SEM, NH 3 /CO 2 -TPD, XPS, and H 2 -TPR, and the results indicated that flower CeO 2 performed the largest acid-base sites and oxygen vacancies as expected, proving its superior physicochemical properties and catalytic activity. Moreover, the catalytic activity synthesis of DMC from CO 2 and methanol was investigated, confirming that the flower CeO 2 owned the highest catalytic performance, and the maximum yield of DMC was 3.11 mmol/g cat. under the reaction conditions (16 MPa, 250 °C, reaction time of 1 h without stirring). Importantly, the synthesis kinetic mechanism of DMC in dual supercritical systems was experimentally studied using the synthetic CeO 2 catalysts, and the flower CeO 2 catalyst possessed the lowest apparent activation energy of 45.9 kJ/mol, meanwhile, the initial reaction rate equation obtained from the experiment can be represented as: Rate = k [*] [CH 3 OH] [CO 2 ]1/2, which was consistent with the reaction mechanism of Langmuir–Hinshelwood type. [Display omitted] • The prepared flower structure CeO 2 (–F) has superior S BET , O V & basic-acidic sites. • CeO 2 –F performs top activity for direct synthesis DMC in dual supercritical fluids. • Characterizations prove the catalytic mechanism of surface O V during DMC synthesis. • Kinetics model of CeO 2 –F is built that can precisely describe the synthesis process. [ABSTRACT FROM AUTHOR]

Highly selective determination of enantiomers by electrochemical sensors with simple recognition elements is of great interest in pharmaceutics, biochemistry and medical fields. The present work developed an innovative electrochemical sensor, which based on boron-embedded molecularly imprinted hybrid film (B-MIHF) modified carbon paste electrode (CPE), for enantioselective determination of S -ornidazole ( S -ONZ). A boron-embedded conductive copolymer was firstly electro polymerized on carbon paste electrode (CPE), and then molecularly imprinted polysiloxanes (MIP) were hydrolyzed and condensed over the conductive copolymer layer via a sol-gel process. The as-prepared B-MIHF, comprised the advantages of boron-embedded conductive copolymer and molecularly imprinted polysiloxanes, could not only implement direct signal transformation between imprinted cavities and sensing elements, but show amazing selectivity to template S -ornidazole. Above all, the introduction of coordinate interaction formed between trisubstituted boron atoms embedded in B-MIHF matrix and nitrogen atoms of template endow the sensor with intensive enantioselectivity. Under optimum experiments conditions, the reduction peak currents of S -ONZ by differential pulse voltammetry were linear to S -ONZ concentrations in the range from 6.0 × 10 −8 to 1.0 × 10 −6 mol L −1 and 1.0 × 10 −6 to 3.5 × 10 −4 mol L −1 with a detection limit of 1.1 × 10 −8 mol L −1 . The B-MIHF-based sensor has been successfully applied for the determination of S -ONZ in pharmaceutical and biological samples with good precision (RSD 2.25–4.11%) and acceptable recoveries (96.00–108.00%). [ABSTRACT FROM AUTHOR]

An innovative electrochemical sensor, based on a carbon paste electrode (CPE) modified with graphene (GR) and a boron-embedded duplex molecularly imprinted hybrid membrane (B-DMIHM), was fabricated for the highly sensitive and selective determination of lamotrigine (LMT). Density functional theory (DFT) was employed to study the interactions between the template and monomers to screen appropriate functional monomers for rational design of the B-DMIHM. The distinct synergic effect of GR and B-DMIHM was evidenced by the positive shift of the reduction peak potential of LMT at B-DMIHM/GR modified CPE (B-DMIHM/GR/CPE) by about 300 mV, and the 13-fold amplification of the peak current, compared to a bare carbon paste electrode (CPE). The electrochemical reduction mechanism of lamotrigine was investigated by different voltammetric techniques. It was illustrated that square wave voltammetry (SWV) was more sensitive than different pulse voltammetry (DPV) for the quantitative analysis of LMT. Thereafter, a highly sensitive electroanalytical method for LMT was established by SWV at B-DMIHM/GR/CPE with a good linear relationship from 5.0×10 −8 to 5.0×10 −5 and 5.0×10 −5 to 3.0×10 −4 mol L −1 with a lower detection limit (1.52×10 −9 mol L −1 ) based on the lower linear range(S/N=3). The practical application of the sensor was demonstrated by determining the concentration of LMT in pharmaceutical and biological samples with good precision (RSD 1.04–4.41%) and acceptable recoveries (92.40–107.0%). [ABSTRACT FROM AUTHOR]

The resonance Raman spectra of the fundamental, combination, and second harmonic modes around the carbon–carbon single and double bonds stretches of all-trans-β-carotene in 1, 2-dichloroethane with iodine solution are obtained in the range of 293–83 K. The Raman scattering cross section of the fundamentals in the liquid (293–213 K) and solid phases (188–83 K) increases as temperature decreases and the Raman bandwidths decreases. An intriguing phenomenon is that the Raman scattering cross section of the carbon-carbon single and double bonds in solution with iodine decreases and the Raman bandwidths increases, compared with the one without iodine. These phenomena are analyzed using the coherent weakly damped electron - lattice vibration mode. [ABSTRACT FROM AUTHOR]

External field plays a very important role in the interaction between the π-electron transition and atomic vibration of polyenes. It has significant effects on both the Huang–Rhys factor and the electron–phonon coupling. In this paper, the visible absorption and resonance Raman spectra of all- trans -β-carotene are measured in the 345–295 K temperature range and it is found that the changes of the 0–1 and 0–2 vibration bands of the absorption spectra with the temperature lead to the different electron–phonon coupling of fundamental, overtone, and combination modes. The electron-phonon coupling constants of all the modes are calculated and analyzed under different temperatures. The variation law of the electron–phonon coupling with the temperature well interprets the changes of the resonance Raman spectra, such as the shift, intensity and line width of the overtone and combination modes, which are all greater than those of the fundamental modes. [ABSTRACT FROM AUTHOR]

Triple-negative breast cancers (TNBCs) are now acknowledged as a collection of diseases encompassing distinct histological plasticity, multi-tier molecular heterogeneity, as well as different outcomes. Despite decades of efforts, the molecular subtyping strategy has been theoretical, and target therapies based on molecular alternations barely improve survival rates of TNBC patients, and thus traditional chemotherapy remains the standard of care in clinic. The Wnt signaling is an evolutionarily conserved signaling pathway, playing critical roles in embryogenesis and neoplastic disease. The dysregulation of Wnt signaling pathway endows cancer cells with stem cell-like capacities of self-renewal, cell proliferation and differentiation, thus exerting crucial roles in tumorigenesis and therapy responses. Recently, the gene expression assays and genomic sequencing have demonstrated that the dysregulation of Wnt signaling is associated with progression of TNBCs, particularly with metastasis, relapse and therapy resistance. In this review, we highlight the dysregulation of Wnt signaling in TNBCs and its potential biological roles in molecular subtyping and stemness traits of specific subtypes, as well as its crosstalk with ncRNAs in regulation of the biological features of TNBCs, aiming to update this important oncogenic signaling pathway in TNBCs. [ABSTRACT FROM AUTHOR]

Insitu high-pressure Raman spectra of S-trioxanehave been measured up to 28 GPa. A first-order phase transition wasdetected at ∼3 GPa from the splitting, newly existing and diminishingof the internal modes and from changes in the slope on plots of frequencyversus pressure. The vibrational spectra and theoretical simulationindicate that the isolated molecule structure changes from puckeredto very puckered structure at the first phase, while at the beginningof the second phase, S-trioxane goes back to itsoriginal puckered structure and loses its C3 axis; then, it changesto planar structure at about ∼GPa and keeps its flat structurein the second phase up to the highest pressure studied. We believethat phase may be a dominant factor responsible for the pressure-inducedplanar molecular geometry, providing a reasonable explanation forthe experimental observations. [ABSTRACT FROM AUTHOR]

Abstract: The temperature-dependent visible absorption and resonant Raman spectra of all-trans-β-carotene extremely diluted in dimethyl sulfoxide are investigated to clarify the effects of temperature on conjugated polyenes. The visible absorption and Raman spectra are found to blueshift with increasing temperature. The blueshift in polyenes is attributed to the decrease in the liquid density and the concomitant decrease in the refractive index by the Lorentz–Lorenz relation. We demonstrate that visible absorption is reproduced well by simple Franck–Condon analysis using a single Huang–Rhys factor over a temperature range. The analysis reveals features of temperature dependence in terms of important spectral parameters, such as line width, Raman scattering cross section and Huang–Rhys factor. [Copyright &y& Elsevier]

Abstract: Raman spectra of benzene, naphthalene and biphenyl have been taken up to a pressure of 13GPa. The results for benzene and naphthalene indicate that the perturbation of inter-molecular π–π stacking effect on the Raman intensity is neglectable. For biphenyl, all the Raman peaks show intensity enhancement during the compression process, which indicates the planar intra-molecular aromatic conformation play an important role in the intensity increments of Raman bands. For three aromatic compounds, C–H stretching vibration bands located at about 3000cm−1 show intriguing intensity changes during compression account for the inter-molecular C–H⋯π interaction. [Copyright &y& Elsevier]

Using the pressure-induced polarized Raman spectra of carbon tetrachloride up to 22 GPa, a significant anomalous polarization (the depolarization ratio >0.75) was observed. We analyzed it by evaluating the antisymmetric anisotropy distribution of modes in T d and explored the corresponded molecular structure having been translated from T d into a lower symmetry. The P21/ c and Pa3 structures of carbon tetrachloride were optimized as a function of pressure to further confirm that the molecules deviated from regular tetrahedra. The C2 v and D2 were analyzed to be candidates of the lower symmetry based on group and Landau theory. [ABSTRACT FROM AUTHOR]

Abstract: We have measured the Raman spectra of liquid CS2 at different volume concentrations in CHCl3 and CH2Cl2 solutions. With decreasing the volume concentration of CS2, a noticeable growth in the band frequency was observed, while the band location remained practically unchanged. This asymmetric wavenumber shift phenomenon of the Fermi doublet and of CS2 has been ascribed to weak, non-conventional hydrogen bonds formed between the CS2 and the solvent molecules. These weak hydrogen bonds were also responsible for significant decreases in the C–H bond symmetric stretching vibration band frequencies of CHCl3 and CH2Cl2. The values of the FR parameters of CS2 in CH2Cl2 and CHCl3 at different volume concentrations were calculated according to the FR theory. The magnitude of the FR coupling coefficient W of CS2 increases upon dilution with CH2Cl2 and CHCl3, indicating that the vibrational anharmonicity is relatively sensitive to variations in the weak hydrogen bonding. Compared with the changing tendencies of Fermi coupling coefficient W of CS2 in CH2Cl2 and CHCl3 at different volume concentrations, we discussed the effect of the weak hydrogen bond formation on the FR and the asymmetric wavenumber shift phenomenon of the Fermi doublet and of CS2. [Copyright &y& Elsevier]

Summary: The primary goal of this work was to identify the sustainable groundwater yield which is a key reference of reasonable groundwater development, but also a complex issue in current hydrogeologic science. One major limit to identify sustainable groundwater yield is the lack of a unified evaluation criterion because there are many factors involved in hydrological systems that are difficult to quantify. To address this problem, an integrated evaluation model was constructed for a series of purposes including the maximal efficiency of water use, the integral benefit of development and utilization, the optimized environmental water demand and the minimal anthropogenic influence on groundwater system. It consists of a benefit model, a water cycling simulation model and an optimization model. The basin-wide model for water cycling simulation was a basic component to simulate scenarios with different constraints, and the best water development strategy was thereafter identified using the integral benefit model of water resources development. The Yinma River basin in a Chinese semi-humid region was selected as the case study area. Results indicated the optimized groundwater yield could be sustained by intensive reservoir supply and maintain suitable ecological water demand simultaneously. The work proposed a potential groundwater utilization strategy for economically developing countries across the world. [ABSTRACT FROM AUTHOR]

The chemical transformation of benzene (C6H6) and carbon disulfide (CS2) binary solutionunder highpressure condition is investigated by means of Raman spectroscopyup to 6.8 GPa. On increasing the pressure, all the Raman bands ofbenzene decrease in intensity, whereas new broad bands start to beobserved at 1520 and 1450 cm–1, indicating thata highly cross-linked polymer is formed. The recovered sample is analyzedthrough Raman and FT-IR spectroscopy and is identified as a saturatedhydrocarbon and element sulfur. [ABSTRACT FROM AUTHOR]

Abstract: A wireless immunosensor for the detection of Mycoplasma genitalium was fabricated by immobilizing polyclonal antibody onto the surface of a magnetostrictive strip. In response to a time-varying magnetic field, the immunosensor longitudinally vibrates at a resonance frequency, emitting magnetic flux that can be remotely detected by a pickup coil. No physical connections between the immunosensor and the detection system are required, facilitating wireless aseptic operation. The binding of M. genitalium to the immunosensor surface resulted in a decrease in the resonance frequency of the immunosensor. When solutions with varying concentrations of the bacteria were tested, the shift of the resonance frequency was proportional to the concentration of M. genitalium. Under the optimized conditions, the linear range for the determination of M. genitalium was 2.0×103 to 2.9×104 color change units (ccu)/ml with a detection limit of 3.4×102 ccu/ml. The immunosensor was successfully applied to real samples containing M. genitalium with results similar to those previously obtained by the color change unit method. [ABSTRACT FROM AUTHOR]

Abstract: Mycoplasma genitalium (Mg) is the smallest and simplest self-replicating bacteria lacking of cell wall and is a human pathogen causing various diseases. This paper describes the real-time, long-term and in situ monitoring of the growth of Mg and evaluation of the effect of the antibiotics tetracycline and levofloxacin on the growth using a wireless magnetoelastic sensor. The sensor is fabricated by coating a magnetoelastic strip with a polyurethane protecting film. In response to a time-varying magnetic field, the sensor longitudinally vibrates at a resonance frequency, emitting magnetic flux that can be remotely detected by a pick-up coil. No physical connections between the sensor and the detection system are required. The wireless property facilitates aseptic operation. The adhesion of Mg on the sensor surface results in a decrease in the resonance frequency, which is proportional to the concentration of Mg. The shift of the resonance frequency–time curves shows that under routine culture condition the growth curve of Mg is composed of three phases those are lag, logarithmic and stationary phase, respectively. In the presence of the antibiotics, the lag phase in the growth inhibition curves is prolonged obviously and the stationary phase is substituted by a decline phase. The growth inhibition of Mg is related to the concentration of the antibiotics. The MIC50 (minimal inhibitory concentration) of Mg incubated in the presence of the antibiotics for 120h is calculated to be 1.5 and 0.5μg/mL for tetracycline and levofloxacin, respectively. [Copyright &y& Elsevier]

Abstract: Aggregates of the diacid form of meso-tetraphenylporphyrin (TPP) were formed by evaporating organic solutions on quartz substrate. The effect of counterions on TPP aggregates, which were obtained through adding various kinds of acids HX(X=HSO4, NO3, Br and Cl) to TPP dichloromethane solution, has been investigated through the combined use of UV–vis absorption and Raman scattering spectroscopy. The protonated TPP and the resulting aggregates exhibited spectroscopic features that were remarkably influenced by the nature of counterions. For all the aggregates, split of the B state absorptions with components red- and blue-shifted relative to their diacid solution values indicated the J-type arrangement of TPP molecules was formed in the aggregates, and the magnitude of this shift was markedly influenced by the nature of the counterions; the (C b −H) in-plane bending vibrational bands in the Raman spectra of the aggregates also showed dependence on counterions. A model for TPP J-aggregates has been proposed on the basis of the angle between transition moment along the chain and the projected line connecting the centers of porphyrins onto the porphyrin plane, and the extended evidence was also obtained by investigation of the Raman spectra of the aggregates from the sulfuric diacid TPP organic (toluene, dichloromethane, acetone and chloroform) solutions, and T(4-NO2P)P, T(4-MeOP)P dichloromethane solutions. [Copyright &y& Elsevier]

Abstract: The compatibility Teflon-AF 2400 liquid core optical fibre with resonance Raman spectroscopy (RRS-LCOF) was used to detect aqueous biomolecules. The maximum sensitivity enhancement factor for concentrations greater than the detection limit in a conventional cell was 10, and detection limit reduction of about 1000-fold have been achieved for the measurement of aqueous absorbing sample using Teflon-AF 2400 fibre Raman cell compared to the conventional cell. We were able to collect spectra of 2.5×10−9 and 2.5×10−10 M aqueous β-carotene using 16.2mW of laser power and 10s integration time. This volume of a 2.5×10−10 M aqueous solution corresponds to only 1.5fmol or 830fg of β-carotene. The results of this preliminary study indicate that RRS-LCOF has potential in bioanalytical and biomedical applications. [Copyright &y& Elsevier]