Characterizing the adsorption of proteins on glass capillary surfaces using electrospray-differential mobility analysis

We quantify the adsorption and desorption of a monoclonal immunoglobulin-G antibody, rituxamab (RmAb), on silica capillary surfaces using electrospray-differential mobility analysis (ES-DMA). We first develop a theory to calculate coverages and desorption rate constants from the ES-DMA data for proteins adsorbing on glass capillaries used to electrospray protein solutions. This model is then used to study the adsorption of RmAb on a bare silica capillary surface. A concentration-independent coverage of ≈4.0 mg/m(2) is found for RmAb concentrations ranging from 0.01 to 0.1 mg/mL. A study of RmAb adsorption to bare silica as a function of pH shows maximum adsorption at its isoelectric point (pI of pH 8.5) consistent with literature. The desorption rate constants are determined to be ≈10(-5) s(-1), consistent with previously reported values, thus suggesting that shear forces in the capillary may not have a considerable effect on desorption. We anticipate that this study will allow ES-DMA to be used as a "label-free" tool to study adsorption of oligomeric and multicomponent protein systems onto fused silica as well as other surface modifications.     

2-(2-Pyridyl) benzimidazole based Co(II) complex as an efficient fluorescent probe for trace level determination of aspartic and glutamic acid in aqueous solution: a displacement approach

A weakly fluorescent cobalt(II) complex is synthesized using 2-(2-pyridyl)-benzimidazole (PBI) as a chelating fluorescent ligand and characterized by single crystal X-ray structure. This complex serves as an efficient fluorescent probe for trace level determination of aspartic acid (AspA) and glutamic acid (GluA) in aqueous solution. Rest of the naturally occurring amino acids did not interfere. Both aspartic acid and glutamic acid replaces PBI from the coordination sphere of Co(II)-PBI complex resulting appearance of strong fluorescence signal for the released free PBI. The signal response is very fast and the interaction of both the AspA and GluA with the Co(II) is strong enough as evident from their displacement equilibrium constant values, viz. 4357.8 M(-1) and 8333.33 M(-1) respectively.     

Crystal Structure and Interaction of 6-Amino Coumarin with Nitrite Ion for Its Selective Fluorescence Detection

ABSTRACT

6-Amino coumarin has been established as an efficient nitrite ion selective fluorescent sensor. The developed method shows linearity up to 1.6 × 10^?6 mol L^?1 of nitrite ion concentration. Interference from other common anions is almost negligible. The reagent shows strong binding affinity towards nitrite ion as evident from its binding constant value (5.8 × 10⁴), estimated by Stern-Volmer method. Some real samples were analyzed. Single crystal X-ray structure of the reagent is reported. Preliminary computational studies on the molecular level interaction between the reagent and nitrite ion were performed by density functional theory (DFT, B3LYP) method.     

Ion chromatography and on-line scintillation counting for the analysis of non-gamma emitting radionuclides in reactor coolant

The use of ion chromatography and on-line scintillation counting for the measurement of non-gamma emitters was evaluated for its applicability to reactor coolant. Potential chemical and radiological interferences were identified and a procedure was developed to eliminate them. The method was tested on a sample of simulated pressurized water reactor coolant.     

Sulfone coupling and double-elimination strategy for carotenoid synthesis

[Reaction: see text]. A highly efficient synthetic method of carotenoid compounds has been developed on the basis of the sulfone coupling and double-elimination strategy. This method highlighted the sulfone-mediated coupling with the novel C(10) dialdehyde, 2,7-dimethyl-4-octenedial, which was easily prepared and efficiently utilized in the synthesis of the conjugated polyene chains.     

Geodesic flows, bi-Hamiltonian structure and coupled KdV type systems

We show that all the Antonowicz-Fordy type coupled KdV equations have the same symmetry group and similar bi-Hamiltonian structures. It turns out that their configuration space is , where is the Bott-Virasoro group of orientation preserving diffeomorphisms of the circle, and all these systems can be interpreted as equations of a geodesic flow with respect to L² metric on the semidirect product space .     

Amplitude modulation and demodulation of an electromagnetic wave in a magnetised semiconductor plasma

The amplitude modulation as well as demodulation of an electromagnetic wave in a transversely magnetised piezoelectric semiconductor plasma has been studied in different wave number regions over a wide range of electron cyclotron frequency.