Two-dimensional titanium carbonitride MXene as a highly efficient electrocatalyst for hydrogen evolution reaction

In this paper, we report, for the first time, on the electrochemical catalytic activity of 2D titanium carbonitride MXene for hydrogen evolution reaction (HER). According to our study, 2D titanium carbonitride exhibited much higher electrocatalytic activity than its carbide analogues, achieving an onset overpotential of 53 ​mV and Tafel slope of 86 ​mV dec−1, superior to the titanium carbide with onset overpotential of 649 ​mV and Tafel slope of 303 ​mV dec−1. The obtained onset overpotential for 2D titanium carbonitride is lower than those of all the reported transition metal carbides MXene catalysts without additives, so far. Density functional theory calculations were conducted to further understand the electrochemical performance. The calculation results show that a greater number of occupied states are active for Ti3CNO2, revealing free energy for the adsorption of atomic hydrogen closer to 0 than that of Ti3C2O2. Both experimental and calculation studies demonstrate the excellent electrocatalytic behavior of titanium carbonitride. The investigation of 2D titanium carbonitride opens up a promising paradigm for the conscious design of high-performance non-precious metal catalyst for hydrogen generation

The Effect of Social and Consumption Analytics on Residential Water Demand

In this paper, the effects of Dropcountr on water usage were examined using household- level panel data for the City of Folsom, California, from January-2013 to September- 2016. Results suggest that the introduction of the Dropcountr services for the population of households participating in Dropcountr causes an aggregate treatment effect of 7% reduction in water usage with a significant variation in the effect across households dependent on baseline consumption quintile. In response to the Dropcountr services, households in the highest quintile of baseline consumption reduce water usage by an estimated 13%

The first step: activation of the semliki forest virus spike protein precursor causes a localized conformational change in the trimeric spike

The structure of the particle formed by the SFVmSQL mutant of Semliki Forest virus (SFV) has been defined by cryo-electron microscopy and image reconstruction to a resolution of 21 Å. The SQL mutation blocks the cleavage of p62, the precursor of the spike proteins E2 and E3, which normally occurs in the trans-Golgi. The uncleaved spike protein is insensitive to the low pH treatment that triggers membrane fusion during entry of the wild-type virus. The conformation of the spike in the SFVmSQL particle should correspond to that of the inactive precursor found in the early stages of the secretory pathway. Comparison of this 'precursor' structure with that of the mature, wild-type, virus allows visualization of the changes that lead to activation, the first step in the pathway toward fusion. We find that the conformational change in the spike is dramatic but localized. The projecting domains of the spikes are completely separated in the precursor and close to generate a cavity in the mature spike. E1, the fusion peptide-bearing protein, interacts only with the p62 in its own third of the trimer before cleavage and then collapses to form a trimer of heterotrimers (E1E2E3)3 surrounding the cavity, poised for the pH-induced conformational change that leads to fusion. The capsid, transmembrane regions and the spike skirts (thin layers of protein that link spikes above the membrane) remain unchanged by cleavage. Similarly, the interactions of the spikes with the nucleocapsid through the transmembrane domains remain constant. Hence, the interactions that lead to virus assembly are unaffected by the SFVmSQL mutation