Competitive Ligand Binding and Photosensitivity Studies of Iron(III)-thiocyanate in presence of Glutamate ion

Addition of a chelating ligand (glutamate ion) to [Fe(SCN)]2+ solution leads to change in the colour. On increasing the glutamate ion concentration in iron thiocyanate complex solution, the colour of [Fe(SCN)]2+ disappears with the emergence of a new peak at lower wavelength due to the formation of [Fe(Glu)]2+complex. The conductance of [Fe(SCN)]2+ complex ion in solution is high while on addition of different concentrations of glutamate ion to iron thiocyanate complex, their conductance value decreases due to formation of [Fe(Glu)]2+. Photosensitivity studies of a series of solutions prepared by the addition of glutamate ion of varying concentrations to ferric chloride-ammonium thiocyanate/potassium thiocyanate solution in the short UV region demonstrate the better stability of [Fe(Glu)]2+compared to [Fe(SCN)]2+ and the rate kinetics of decomposition has been reported.

Hierarchy in the Avidity and Cross-reactivity of Anti-citrullinated Protein Antibodies in the Serum of Patients With Rheumatoid Arthritis

BackgroundFine specificity of anti-citrullinated protein antibodies (ACPAs), in which cross-reactivity exists, varies among patients with rheumatoid arthritis (RA), but it is unclear whether the mechanism of ACPA production is same or different among individuals. Since avidity of serum antibody reflects the direction of immune response, we compared the levels of avidity and cross-reactivity between various ACPAs in a cohort of RA patient.MethodsSera from 180 RA patients positive for anti-cyclic citrullinated peptide (CCP) 2 antibody were screened for positivity of antibodies against CCP1, and citrullnated fibrinogen (cFib), enolase (cEno), and vimentin (cVim) peptides. Avidity of the four ACPAs, and some autoantibodies and antibodies against foreign antigens was determined by an elution assay using sodium thiocyanate solution. Cross-reactivity between different ACPAs was estimated by measuring the inhibition of binding by competitor peptides. ResultsThe prevalence of anti-CCP1, anti-cFib, anti-cEno, and anti-cVim antibodies in the anti-CCP2-positive RA cohort were 37.7%, 38.3%, 15.6%, and 23.9%, respectively. The avidity of ACPAs, except for anti-cVim antibody, was significantly lower than that of antibodies against foreign antigens, while there was a large variety in the avidity of other autoantibodies. At individual levels, the avidity of anti-cVim was significantly higher than that of other ACPAs, and there was a significant correlation in the avidity of anti-CCP and anti-cFib antibodies. Substantial extent of cross-reactivity was seen between different ACPAs, which also showed a fixed hierarchy.ConclusionThe fixed hierarchy in the avidity and cross-reactivity between different ACPAs suggests that the mechanism underlying ACPA production is common to all RA patients. Presence of a dominant antigen that induces whole ACPA response is speculated.

Thiocyanate-Treated Perovskite-Nanocrystal-Based Light-Emitting Diodes with Insight in Efficiency Roll-Off

Light emitting diodes (LED) based on halide perovskite nanocrystals (NC) have received widespread attention in recent years. In particular, LEDs based on CsPbBr3 NCs were the object of special interest. Here, we report for the first time green LED based on CsPbBr3 NCs treated with ammonium thiocyanate solution before purification with polar solvent. The champion device fabricated based on the treated CsPbBr3 NCs showed high efficiency and high stability during operation as well as during storage. A study on morphology and current distribution of NC films under applied voltages was carried out by conductive atomic force microscopy, giving a hint on efficiency roll-off. The current work provides a facile way to treat sensitive perovskite NCs and to fabricate perovskite NC-based LED with high stability. Moreover, the results shed new light on the relation between film morphology and device performance and on the possible mechanism of efficiency roll-off in NC LED.

Guanidine thiocyanate solution facilitates sample collection for plant rhizosphere microbiome analysis

The interactions between rhizosphere microorganisms and plants are important for the health and development of crops. Analysis of plant rhizosphere bacterial compositions, particularly of those with resistance to biotic/abiotic stresses, may improve their applications in sustainable agriculture. Large-scale rhizosphere samplings in the field are usually required; however, such samples, cannot be immediately frozen. We found that the storage of samples at room temperature for 2 days leads to a considerable reduction in the operational taxonomic unit (OTU) number and the indices of bacterial alpha-diversity of rhizosphere communities. In this study, in order to overcome these problems, we established a method using guanidine thiocyanate (GTC) solution for the preservation of rhizosphere samples after their collection. This method allowed the maintenance of the samples for at least 1 day at room temperature prior to their cryopreservation and was shown to be compatible with conventional DNA isolation protocols. Illumina sequencing of V3 and V4 hypervariable regions of the 16S rRNA gene was used to assess the feasibility and reliability of this method, and no significant differences were observed in the number of OTUs and in the Chao and Shannon indices between samples stored at −70 °C and those stored in GTC solution. Moreover, the representation of Pseudomonas spp. in samples stored in GTC solution was not significantly different from that in samples stored at −70 °C, as determined by real-time quantitative polymerase chain reaction (p > 0.05). Both types of samples were shown to cluster together according to principal coordinate analysis. Furthermore, GTC solution did not affect the bacterial taxon profiles at different storage periods compared with those observed when storing the samples below −70 °C. Even incubation of thawed samples (frozen at −70 °C) for 15 min at room temperature induced minor changes in the bacterial composition. Taken together, our results demonstrated that GTC solution may provide a reliable alternative for the preservation of rhizosphere samples in the field.