Electrical resistivity of iron-vanadium alloys between 78 and 1200 K

Electrical resistivity (?) of FeV alloys containing 0.5, 0.9, 2.7, and 6.1 at% V has been measured as a function of temperature (T) between 78 and 1200 K. The ? vs. T curves exhibit a change in the slope at the ferromagnetic Currie temperature (T_c). The d?/dT vs. T curves in the neibhorhood of T_c are similar to the corresponding plot for pure Fe. Our studies confirm the previously observed anomalous effect of V on T_c of Fe, i.e., that T_c increase with small additions of V to Fe. The critical index λ⁺ associated with the power law of d?/dT just above T_c has been determined as a function of V concentration.     

Synthesis and Systematic Evaluation of Dark Resonance Energy Transfer (DRET)‐Based Library and Its Application in Cell Imaging

In this paper, we report a new strategy for constructing a dye library with large Stokes shifts. By coupling a dark donor with BODIPY acceptors of tunable high quantum yield, a novel dark resonance energy transfer (DRET)‐based library, named BNM , has been synthesized. Upon excitation of the dark donor ( BDN ) at 490 nm, the absorbed energy is transferred to the acceptor ( BDM ) with high efficiency, which was tunable in a broad range from 557 nm to 716 nm, with a high quantum yield of up to 0.8. It is noteworthy to mention that the majority of the non‐radiative energy loss of the donor was converted into the acceptor’s fluorescence output with a minimum leak of donor emission. Fluorescence imaging tested in live cells showed that the BNM compounds are cell‐permeable and can also be employed for live‐cell imaging. This is a new library which can be excited through a dark donor allowing for strong fluorescence emission in a wide range of wavelengths. Thus, the BNM library is well suited for high‐throughput screening or multiplex experiments in biological applications by using a single laser excitation source.     

Novel modified ultrasonication technique for the extraction of lycopene from tomatoes

Lycopene extraction was carried out via the ultrasonic assisted extraction (UAE) with response surface methodology (RSM). Sonication enhanced the efficiency of relative lycopene yield (enhancement of 26% extraction yield of lycopene in 6 replications at 40.0 min, 40.0 °C and 70.0% v/w in the presence of ultrasound), lowered the extraction temperature and shortened the total extraction time. The extraction was applied with the addition of oxygen-free nitrogen flow and change of water route during water bath sonication. The highest relative yield of lycopene obtained was 100% at 45.0 °C with total extraction time of 50.0 min (30:10:10) and ratio of solvent to freeze-dried tomato sample (v/w) of 80.0:1. Optimisation of the lycopene extraction had been performed, giving the average relative lycopene yield of 99% at 45.6 min, 47.6 °C and ratio of solvent to freeze-dried tomato sample (v/w) of 74.4:1. From the optimised model, the average yield of all-trans lycopene obtained was 5.11 ± 0.27 mg/g dry weight. The all-trans lycopene obtained from the high-performance liquid chromatography (HPLC) chromatograms was 96.81 ± 0.81% with 3.19 ± 0.81% of cis-lycopenes. The purity of total-lycopene obtained was 98.27 ± 0.52% with β-carotene constituted 1.73 ± 0.52% of the extract. The current improved, UAE of lycopene from tomatoes with the aid of RSM also enhanced the extraction yield of trans-lycopene by 75.93% compared to optimised conventional method of extraction. Hence, the current, improved UAE of lycopene promotes the extraction yield of lycopene and at the same time, minimises the degradation and isomerisation of lycopene.     

Structure and optical properties of Ag/CeO2 nanocomposites

Silver/ceria (Ag/CeO₂) nanocomposites were prepared from Ce(NO₃)₃?6H₂O, AgNO₃, and NH₄OH with different molar ratios through a hydrothermal process, and then were completed by carrying out the precursors calcining at 750 °C for 2 h under air atmosphere. Below 1 % of Ag concentration in Ag/CeO₂ nanocomposites, the Ag crystalline structure does not appear. XRD and TEM results show evidence of two different effects (the agglomeration and the barrier effects) governing the process of crystal growth. HR-TEM image and EDX elemental analysis of the Ag/CeO₂ nanocomposite confirmed that isolated Ag nanocrystals are dispersed in the CeO₂ matrix. The red shifts are attributed to the quantum confinement effect and the valence change of the Ce⁺ ions. Ag nanoparticles can help to improve the absorption of visible light, enhancing the absorption intensity of Ag/CeO₂ nanocomposite. These results are of great significance for the control of microstructure, crystallinity, and applications for the development of nanocomposite materials.     

Flavone enhances dengue virus type-2 (NGC strain) infectivity and replication in vero cells

This study investigates the effects of 2-phenyl-1-benzopyran-4-one (flavone) on DENV-2 infectivity in Vero cells. Virus adsorption and attachment and intracellular virus replication were investigated using a foci forming unit assay (FFUA) and quantitative RT-PCR, respectively. Addition of flavone (100 μg/mL) significantly increased the number of DENV-2 foci by 35.66% ± 1.52 and 49.66% ± 2.51 when added during and after virus adsorption to the Vero cells, respectively. The average foci size after 4 days of infection increased by 33% ± 2.11 and 89% ± 2.13. The DENV-2 specific RNA copy number in the flavone-treated infected cells increased by 6.41- and 23.1-fold when compared to the mock-treated infected cells. Flavone (100 μg/mL) did not promote or inhibit Vero cell proliferation. The CC?? value of flavone against Vero cells was 446 μg/mL. These results suggest that flavone might enhance dengue virus replication by acting antagonistically towards flavonoids known to inhibit dengue virus replication.     

The effects of the nanostructure of mesoporous TiO<Subscript>2</Subscript> on optical band gap energy

Mesoporous TiO₂ is prepared by sol–gel process with a triblock copolymer as an organic template and aqueous TiOCl₂ solution as inorganic precursor. The XRD patterns reveal that only the anatase phase can be observed in mesoporous TiO₂, regardless of the different calcining temperatures, and with increasing calcining temperature the grain size gradually increases. The grain sizes of TiO₂ increased from 4.7 to 11.9 nm with calcining temperature increasing from 300 to 400 °C. The pore size and the surface area evaluated from the Barrett–Joyner–Halenda model and Brunauer–Emmett–Teller method indicated that the average pore sizes increased from 87 to 153 Å and specific surface areas decreased from 179.71 to 74.31 m²/g for 300–400 °C calcination. The relationship between the optical band gap (E _g) and microstructure of anatase has been determined and discussed. The quantum confinement effect is observed at grain sizes lower than 10 nm, and the estimated E _g shifts from 3.32 to 3.46 eV. These results suggest that there are potential applications of mesostructured TiO₂ with nanocrystals in the design of optical devices and photocatalysts.     

A new oxathiolane from Enterobacter cloacae

Enterobacter cloacae is a versatile bacterial species inhabiting a wide variety of niches and is capable of metabolising a wide variety of substances as energy resources. The fermentation culture of this bacterial species has successfully yielded one new compound, Rimboxa (1) and three known compounds, i.e. indole-3-carboxaldehyde (2), indole-3-acetic acid (3) and 3,4-di-t-butylaniline (4). Rimboxa (1) is shown to possess the 1,2-oxathiolane core structure. 3,4-Di-t-butylaniline (4) is isolated for the first time from a natural resource. These compounds were isolated and characterised using extensive chromatographic and spectroscopic methods, and were subjected to cytotoxicity evaluations.     

Electric double layer capacitor based on activated carbon electrode and biodegradable composite polymer electrolyte

A series of polymer electrolyte based on poly(vinyl alcohol), lithium perchlorate (LiClO₄), and antimony trioxide (Sb₂O₃) was prepared via solution casting technique with distilled water as solvent. The dielectric behavior study reveals the non-Debye properties of the polymer electrolytes. In frequency dependence conductivity measurement, dispersion at low frequency was due to the interfacial resistance and space charge polarization inside the polymer electrolytes. The linear sweep voltammetry has proven that the incorporation of Sb₂O₃ into polymer matrix increases the maximum operational potential region. Electric double-layer capacitors (EDLCs) based on activated carbon electrode assembled with solid polymer electrolyte and composite polymer electrolyte has been evaluated by cyclic voltammetry (CV) and galvanostatic charge–discharge technique. CV test disclosed rectangular shapes with slight distortion, and there is no evidence for any redox currents on both anodic and cathodic sweeps, which indicates the typical behavior of EDLC. Both EDLC cells demonstrate good cyclability throughout 200 cycles with specific capacitance retention more than 90 %.     

Breaking the limitation of composition change during isothermal mass-transfer processes at the spinodal

A governing equation describing the mass-transfer fluxes in practical membrane formation is derived using Markoffian and Onsager's thermodynamic systems. This equation unambiguously demonstrates that isothermal mass-transfer fluxes at the spinodal composition may not be zero for systems operated in the gravitational field. This study suggests that the mass transfer equations derived by Cheng and Gryte are a special case of the present study and are not fully capable of describing the mass transfer in practical membrane formation. Experimental results published in previous literature qualitatively support our assessment. The limitations of using Markoffian and Onsager's thermodynamic systems for membrane formation study are also reviewed. In conclusion, new thermodynamic theories for polymer solutions are needed to quantitatively describe the mass transfer fluxes in practical membrane formation.