Probing electrolyte influence on CO2 reduction in aprotic solvents

Selective CO2 capture and electrochemical conversion is an important tool in the fight against climate change. Industrially, CO2 is captured using a variety of aprotic solvents due to their high CO2 solubility. However, most research efforts on electrochemical CO2 conversion use aqueous media and are plagued by competing hydrogen evolution reaction (HER) from water breakdown. Fortunately, aprotic solvents can circumvent HER; making it important to develop strategies that enable integrated CO2 capture and conversion in an aprotic solvent. However, the influence of ion solvation and solvent selection within nonaqueous electrolytes for efficient and selective CO2 reduction is unclear. In this work, we show that bulk solvation behavior within the nonaqueous electrolyte can control the CO2 reduction reaction and product distribution occurring at the catalyst-electrolyte interface. We study different TBA (tetrabutylammonium) salts in two electrolyte systems with glyme-ethers (e.g., 1,2 dimethoxyethane or DME) and dimethylsulfoxide (DMSO) as a low and high dielectric constant medium, respectively. Using spectroscopic tools, we quantify the fraction of ion pairs that form within the electrolyte and show how ion-pair formation is prevalent in DME electrolytes and is dependent on anion type. More importantly, we show as ion-pair formation decreases within the electrolyte, CO2 current densities increases, and a higher CO Faradaic efficiency is observed at low overpotentials. Meanwhile, in an electrolyte medium where ion-pair fraction does not change with anion type (such as in DMSO), a smaller influence of solvation was observed on CO2 current densities and product distribution. By directly coupling bulk solvation to interfacial reactions and product distribution, we showcase the importance and utility of controlling the reaction microenvironment in tuning electrocatalytic reaction pathways. Insights gained from this work will enable novel electrolyte design for efficient and selective CO2 conversion to desired fuels and chemicals

Vibrational Communication of Scolypopa australis (Walker, 1851) (Hemiptera: Ricaniidae)—Towards a Novel Sustainable Pest Management Tool

A study was undertaken to determine whether Scolypopa australis, the passionvine hopper, communicates using substrate-borne vibrations, as its use of such signals for communication is currently unknown. This insect is a costly pest to the kiwifruit industry in New Zealand, where few pest management tools can be used during the growing season. Vibrations emitted by virgin females and males of S. australis released alone on leaves of Griselinia littoralis were recorded with a laser vibrometer to identify and characterise potential spontaneous calling signals produced by either sex. In addition to single-insect trials, preliminary tests were conducted with female–male pair trials to determine whether individuals exchanged signals. The signal repertoire of S. australis includes a male calling signal and two female calling signals. However, no evidence of duetting behaviour that is potentially necessary for pair formation has been found to date. Our outcome suggests that a deeper understanding of the role of vibrational communication employed by S. australis is needed, and by disclosing the pair formation process, a new residue-free pest management tool against this pest may be developed. In addition, this vibration-based tool could contribute to future biosecurity preparedness and response initiatives.

Localised Pair Formation in Bosonic Flat-Band Hubbard Models

Flat-band systems are ideal model systems to study strong correlations. In a large class of one or two dimensional bosonic systems with a lowest flat-band it has been shown that at a critical density the ground states are Wigner crystals. Under very special conditions it has been shown that pair formation occurs if one adds another particle to the system. The present paper extends this result to a much larger class of lattices and to a much broader region in the parameter space. Further, a lower bound for the energy gap between these pair states and the rest of the spectrum is established. The pair states are dominated by a subspace spanned by states containing a compactly localised pair. Overall, this strongly suggests localised pair formation in the ground states of the broad class of flat-band systems and rigorously proves it for some of the graphs in it, including the inhomogeneous chequerboard chain as well as two novel examples of regular two dimensional graphs. Physically, this means that the Wigner crystal remains intact if one adds a particle to it.

The Ion Pair Thermal Model of MALDI MS

The ion pair thermal model for MALDI MS is described. Key elements of the model include thermal desorption and ionization, strong tendency to neutralization via ion pair formation and proton transfer in the gas phase, thermal equilibrium, overall charge neutral plume, and thermal energy assisted free ion generation via ion pair separation by ion extraction potential. The quantities of ions in the solid sample and in the gaseous plume are estimated. Ion yields of different classes of molecules including peptides, nucleic acids, permanent salts and neutral molecules are estimated at the macroscale and single ion pair levels. The estimated ion yields are close to experimentally observed values under certain assumptions. Explanations of several observations in MALDI MS such as mostly single-charged peaks, improvement of spectra by ammonium cation, and ion suppression are provided. We expect that the model can give insights for the design of new conditions and systems for improving the sensitivity and resolution of MALDI MS and improving its capability and reliability to analyze large biomolecules.

Conductometric studies of 1, 3, 5 –triazinothiocarbamide at different concentration and temperature

Conductivity plays vital role in drug diffusion. Thermodynamic parameters affected by substituents of drug. Thermodynamic parameters of 1, 3, 5 –triazinothiocarbamide (1a) have been investigated by using conductometrically carried out at different molar concentrations. This work highlights investigation of G, K and µ values. The thermodynamic parameters viz. ΔH, ΔS and ∆G for ion pair formation determine from the value of ion association constant. This technique is suitable and accurate to study of pharmokinetics and pharmodynamics parameters.