Selective oxidative degradation of azo dyes by hydrogen peroxide catalysed by manganese(II) ions

Manganese(II) ions catalyse the oxidative degradation of Calmagite (H3CAL) dye in aqueous solution at 20 ± 1 °C in the pH range 7.5–9.0 using hydrogen peroxide (H2O2) as oxidant by a mechanism that involves strong complexation to the MnII centre. It is proposed that [MnIII(CAL)(O2H)]− i.e. a dye coordinated hydroperoxyl (O2H−) MnIII complex is formed and bleaching of the dye is initiated by an electron-transfer to MnIII, with the binding of H2O2 being the rate determining step. At pH 9.0 in (bi)carbonate, HCO3−, H3CAL is rapidly bleached via the in situ formation of coordinated peroxycarbonate (HCO4−); a TOF (TOF = moles of dye bleached per mole of manganese per hour) of ∼5000 h−1 can be achieved. The bleaching of the related azo dyes Orange II and Orange G is different because, unlike Calmagite, they lack an o,o-dihydroxy motif so are unable to complex strongly to MnII and no oxidation to MnIII occurs. At pH 8.0 (phosphate buffer) Orange II and Orange G are not bleached but bleaching can be achieved at pH 9.0 (HCO3− buffer); the rate determining step is dye coordination and it is proposed bleaching is achieved via an outer-sphere oxygen atom transfer. Mechanisms for dye bleaching at pH 8.0 and pH 9.0 are proposed using data from EPR, UV/VIS and ESI-MS. MnII/H2O2/HCO3− form a potent oxidising mixture that is capable of removing stubborn stains such as curcumin

SARS-CoV-2 Omicron-B.1.1.529 leads to widespread escape from neutralizing antibody responses

On 24th November 2021, the sequence of a new SARS-CoV-2 viral isolate Omicron-B.1.1.529 was announced, containing far more mutations in Spike (S) than previously reported variants. Neutralization titers of Omicron by sera from vaccinees and convalescent subjects infected with early pandemic Alpha, Beta, Gamma, or Delta are substantially reduced, or the sera failed to neutralize. Titers against Omicron are boosted by third vaccine doses and are high in both vaccinated individuals and those infected by Delta. Mutations in Omicron knock out or substantially reduce neutralization by most of the large panel of potent monoclonal antibodies and antibodies under commercial development. Omicron S has structural changes from earlier viruses and uses mutations that confer tight binding to ACE2 to unleash evolution driven by immune escape. This leads to a large number of mutations in the ACE2 binding site and rebalances receptor affinity to that of earlier pandemic viruses

Measurements of Prompt and MHD-Induced Fast Ion Loss from National Spherical Torus Experiment Plasmas

A range of effects may make fast ion confinement in spherical tokamaks worse than in conventional aspect ratio tokamaks. Data from neutron detectors, a neutral particle analyzer, and a fast ion loss diagnostic on the National Spherical Torus Experiment (NSTX) indicate that neutral beam ion confinement is consistent with classical expectations in quiescent plasmas, within the {approx}25% errors of measurement. However, fast ion confinement in NSTX is frequently affected by magnetohydrodynamic (MHD) activity, and the effect of MHD can be quite strong

Ontogenetic shift in dietary preference and low dietary overlap in rohu (Labeo rohita) and common carp (Cyprinus carpio)in semi-intensive polyculture ponds

In order to investigate ontogenetic changes in diet and diet overlap between rohu (Labeo rohita) and common carp (Cyprinus carpio) in polyculture ponds, food preferences of different size classes of these fishes were quantified. Rohu diet consisted of both phytoplankton and zooplankton, and there was a distinct ontogenetic shift in the relative importance of these food items. Zooplankton was the dominant food for rohu up to 20.6 cm total length (TL) and then gradually decreased in importance as fish grew. Phytoplankton was initially a minor component of rohu diet but gradually increased in importance and became the dominant food for rohu at 24.2 cm TL. Phytoplankton biovolume in rohu guts was positively correlated with fish size (TL). Chesson’s a indicated that rohu of all sizes preferentially selected Cladocera and avoided Cyanophyceae and Euglenophyceae. Young rohu initially preferred Rotifera and Copepoda but gradually switched to Bacillariophyceae and Chlorophyceae. Common carp diet consisted of phytoplankton, zooplankton,and benthic macroinvertebrates, but was dominated by benthic macroinvertebrates (63–92% of total diet). As common carp grew, the proportion of zooplankton ingested decreased and the proportion of benthic macroinvertebrates increased. Benthic macroinvertebrate biovolume in common carp guts was positively correlated with fish size. Common carp of up to 15.4 cm TL preferentially selected zooplankton, but common carp larger than 18.9 cm TL avoided this food item. Common carp of all sizes avoided phytoplankton. A low dietary overlap was found between rohu and common carp (Schoener overlap index: 0.08–0.35), probably due to ingestion of smaller quantities of zooplankton by the latter. Dietary overlap also decreased with increasing rohu and common carp size because of divergent ontogenetic shifts in dietary preferences of the two species