Kinetic studies of dyes sorption from aqueous solutions onto the strongly basic anion-exchanger Lewatit MonoPlus M-600

The sorption of Tartrazine, Allura Red, Sunset Yellow and Indigo Carmine from aqueous solutions onto the strongly basic anion-exchanger (Lewatit MonoPlus M-600) of dimethylethanolamine functional groups and styrene–divinylbenzene matrix was investigated. The experimental data obtained at 50, 100, 200, 300 and 500 mg/dm³ initial concentrations at 20 °C were applied to the pseudo-first order, pseudo-second order and Weber–Morris kinetic models. The calculated sorption capacities (q_1,cal) and the rate constant of the first-order adsorption (k₁) were determined. The pseudo-second order kinetic constants (k₂) and capacities (q_2,cal) were calculated from the plots of t/q_t vs. t, 1/q_t vs. 1/t, 1/t vs. 1/q_t, q_t/t vs. q_t and 1/q₂ − q_t vs. t for type 1, type 2, type 3, type 4 and type 5 of the pseudo-second order expression, respectively.     

Spectral studies of zinc octacarboxyphthalocyanine aggregation

The association of zinc octacarboxyphthalocyanine, was studied using UV–vis absorption and fluorescence emission spectroscopy; the effects of dye concentration, pH and solvents on spectra were discussed. Calculations showed that the dye dimerized in aqueous solutions ranging from 5.0 × 10^?7 to 5.0 × 10^?5 mol/dm³, at 25 °C. The dimerization constant of 10⁶ dm³/mol and the spectral Q band shift of 1185 cm^?1 imparted by dimerization indicated strong π–π interactions between phthalocyanine molecules. Red S₁ fluorescence of the dye monomer was observed in various solutions which was quenched owing to molecular association and other factors. The strong influence of pH on both aggregation and fluorescence was discussed. At pH < 5.0, only dye aggregates were present in solution; monomers appeared at pH ≥ 5.0 and, in alkaline solution, only the monomeric anions of phthalocyanine existed. The spectral absorption and emission data for the dye in binary solvents revealed that at concentrations ranging from 0.5 × 10^?5 to 1.0 × 10^?5 mol/dm³, the dye can be used in photosensitised oxidation reactions.     

Scaling up microbial fuel cells

The goal of this study was to quantify the relation between the surface area of the current-limiting electrode of a microbial fuel cell (MFC) and the power density generated by the MFC. Shewanella oneidensis (MR-1) was grown anaerobically in the anodic compartment of an MFC utilizing lactate as the electron donor. Graphite plate electrodes of various sizes were used as anodes. Commercially available air electrodes, composed of manganese-based catalyzed carbon bonded to a current-collecting screen made of platinum mesh, were used as cathodes, and dissolved oxygen was used as the cathodic reactant. The surface area of the cathode was always significantly larger than that of the anode, to ensure that the anode was the current-limiting electrode. The power density generated by the MFC decreased as the surface area of the anode increased, which fits well with the trend we detected comparing various published results. Thus, our findings bring into question the assertion that the overall power density generated by an MFC with large electrodes can be estimated by extrapolating from an electrode with a small surface area. Our results indicate that the maximum power density generated by an MFC is not directly proportional to the surface area of the anode, but is instead proportional to the logarithm of the surface area of the anode.     

Nido-Hydroborate-Based Electrolytes for All-Solid-State Lithium Batteries

Hydroborate-based solid electrolytes have recently been successfully employed in high voltage, room temperature all-solid-state sodium batteries. The transfer to analogous lithium systems has failed up to now due to the lower conductivity of the corresponding lithium compounds and their high cost. Here LiB₁₁H₁₄ nido-hydroborate as a cost-effective building block and its high-purity synthesis is introduced. The crystal structures of anhydrous LiB₁₁H₁₄ as well as of LiB₁₁H₁₄-based mixed-anion solid electrolytes are solved and high ionic conductivities of 1.1 × 10⁻⁴ S cm⁻¹ for Li₂(B₁₁H₁₄)(CB₁₁H₁₂) and 1.1 × 10⁻³ S cm⁻¹ for Li₃(B₁₁H₁₄)(CB₉H₁₀)₂ are obtained, respectively. LiB₁₁H₁₄ exhibits an oxidative stability limit of 2.6 V versus Li⁺/Li and the proposed decomposition products are discussed based on density functional theory calculations. Strategies are discussed to improve the stability of these compounds by modifying the chemical structure of the nido-hydroborate cage. Galvanostatic cycling in symmetric cells with two lithium metal electrodes shows a small overpotential increase from 22.5 to 30 mV after 620 h (up to 0.5 mAh cm⁻²), demonstrating that the electrolyte is compatible with metallic anodes. Finally, the Li₂(B₁₁H₁₄)(CB₁₁H₁₂)  electrolyte is employed in a proof-of-concept half cell with a TiS₂ cathode with a capacity retention of 82% after 150 cycles at C/5.     

Interleukins 6 and 15 Levels Are Higher in Subcutaneous Adipose Tissue,but Obesity Is Associated with Their Increased Content in Visceral Fat Depots

Excess adiposity is associated with chronic inflammation, which takes part in the development of obesity-related complications. The aim of this study was to establish whether subcutaneous (SAT) or visceral (VAT) adipose tissue plays a major role in synthesis of pro-inflammatory cytokines. Concentrations of interleukins (IL): 1β, 6, 8 and 15 were measured at the protein level by an ELISA-based method and on the mRNA level by real-time PCR in VAT and SAT samples obtained from 49 obese (BMI > 40 kg/m²) and 16 normal-weight (BMI 20–24.9 kg/m²) controls. IL-6 and IL-15 protein concentrations were higher in SAT than in VAT for both obese (p = 0.003 and p < 0.0001, respectively) and control individuals (p = 0.004 and p = 0.001, respectively), while for IL-1β this was observed only in obese subjects (p = 0.047). What characterized obese individuals was the higher expression of IL-6 and IL-15 at the protein level in VAT compared to normal-weight controls (p = 0.047 and p = 0.016, respectively). Additionally, obese individuals with metabolic syndrome had higher IL-1β levels in VAT than did obese individuals without this syndrome (p = 0.003). In conclusion, concentrations of some pro-inflammatory cytokines were higher in SAT than in VAT, but it was the increased pro-inflammatory activity of VAT that was associated with obesity and metabolic syndrome.     

Influence of the impact sintering temperature on the structure and properties of samples from the different iron powders

The studies of the consolidation, structure and mechanical properties of samples from two types of iron powder are carried out. The coarse and less pure PZH3M2 as well as fine and purer DIAFE5000 powders were used. The samples are obtained by means of impact sintering method in the temperatures range of 500–1100 °C. The impact energy was 1200 J/cm³, and the initial deformation velocity - 6.5 m/s. Samples are obtained in the form of disks with a diameter of 25–27 mm and 9–10 mm high. For carrying out different mechanical tests the bars were cut out from disks. The tensile, compression, three-point bend of notched samples tests were carried out, as well as the Brinell hardness was measured after the corresponding processing of the bars. The characteristics of strength and plasticity of samples depending on the impact sintering temperature are determined. The polished surface of different samples and the fracture surface are investigated. It is established that the high density of samples is reached at a temperature of 600 and 700 °C respectively for fine and coarse powders. The samples obtained at these impact sintering temperatures possess rather low electrical resistivity, high strength, hardness, but the lowered plasticity. Namely, the samples from the PZH3M2 and DIAFE5000 powders sintered at the temperature of 700 °C have respectively: ultimate tensile strength - 406 and 336 MPa, yield stress - 353 and 190 MPa, contraction ratio - 26 and 78%, limit stress (at the fracture) - 501 and 933 MPa, the maximum crack tip stress – 738 and 876 MPa, the fracture energy at a bend of the notched samples - 4.8 and 51.2 J/cm³ and also Brinell hardness - 1467 and 847 MPa. The increase of the samples impact sintering temperature leads to grain growth, decrease of the samples strength and increase of their plasticity. At the same time the structure of samples from the DIAFE5000 powder is more fine-grained than at samples from the PZH3M2 powder.     

Investigation of the structure of poly(p-chlorophenyl glycidyl ether) by the 13C n.m.r. technique: tacticity and addition isomerism

The p-chlorophenyl glycidyl ether was polymerized in the presence of Al(OiPr)₃, ZnCl₂, SnCl₄, BuOK, KOH and by the Al(OiPr)₃ZnCl₂ 1:1 initiator system. Analysis of the ¹³C n.m.r. spectra of the poly(p-chlorophenyl glycidyl ethers) obtained has made it possible to determine their tacticity and the content of the head-to-tail and head-to-head linkages in the polymer chain.