Category Archives: Research Chemicals

Research Chemicals News: Researchers have found that Natural gas usage wont have an effect on carbon dioxide emissions

Buy research chemicals – Abundant supplies of natural gas will do little to reduce harmful U.S. emissions causing climate change, according to researchers at UC Irvine, Stanford University, and the nonprofit organization Near Zero. They found that inexpensive gas boosts electricity consumption and hinders expansion of cleaner energy sources, such as wind and solar.

The study results, which appear Sept. 24 in the journal Environmental Research Letters, are based on modeling the effect of high and low gas supplies on the U.S. power sector. Coal-fired plants, the nation’s largest source of power, also produce vast quantities of carbon dioxide, the main

greenhouse gas polluting Earth’s atmosphere. Recently proposed rules by the U.S. Environmental Protection Agency rely heavily on the substitution of natural gas for coal to lower carbon emissions by 2030. You can get research chemicals from Chris over at the Research Chemical Shop.

“In our results, abundant natural gas does not significantly lower greenhouse gas emissions. This is true even if no methane leaks during production and shipping,” said lead author Christine Shearer, a postdoctoral scholar in Earth system science at UC Irvine.

Previous studies have focused on the risk of natural gas — composed primarily of methane — leaking into the atmosphere from wells and pipelines. But the new work shows that even if no methane escapes, the overall climate benefits of gas are likely to be small because its use delays the widespread construction of low-carbon energy facilities, such as solar arrays.

Analyzing a range of climate policies, the researchers found that high gas usage could actually boost cumulative emissions between 2013 and 2055 by 5 percent — and, at most, trim them by 9 percent.

“Natural gas has been presented as a bridge to a low-carbon future, but what we see is that it’s actually a major detour. We find that the only effective paths to reducing greenhouse gases are a regulatory cap or a carbon tax,” Shearer said.

She and her co-authors conclude that greater use of gas is a poor strategy for clearing the atmosphere.

“Cutting greenhouse gas emissions by burning natural gas is like dieting by eating reduced-fat cookies,” said Steven Davis, assistant professor of Earth system science at UC Irvine and the study’s principal investigator. “It may be better than eating full-fat cookies, but if you really want to lose weight, you probably need to avoid cookies altogether.”

Geometric and Electronic Structure Contributions to Function in Non-heme Iron Enzymes

Buy research chemicals – Mononuclear non-heme Fe (NHFe) enzymes play key roles in DNA repair, the biosynthesis of antibiotics, the response to hypoxia, cancer therapy, and many other biological processes. These enzymes catalyze a diverse range of oxidation reactions, including hydroxylation, halogenation, ring closure, desaturation, and electrophilic aromatic substitution (EAS).

Most of these enzymes use an FeII site to activate dioxygen, but traditional spectroscopic methods have not allowed researchers to insightfully probe these ferrous active sites. We have developed a methodology that provides detailed geometric and electronic structure insights into these NHFeII active sites. Using these data, we have defined a general mechanistic strategy that many of these enzymes use: they control O2 activation (and limit autoxidation and self-hydroxylation) by allowing FeII coordination unsaturation only in the presence of cosubstrates.

Depending on the type of enzyme, O2 activation either involves a 2e reduced FeIII–OOH intermediate or a 4e reduced FeIV═O intermediate. Nuclear resonance vibrational spectroscopy (NRVS) has provided the geometric structure of these intermediates, and magnetic circular dichroism (MCD) has defined the frontier molecular orbitals (FMOs), the electronic structure that controls reactivity. This Account emphasizes that experimental spectroscopy is critical in evaluating the results of electronic structure calculations. Therefore these data are a key mechanistic bridge between structure and reactivity.

Research Chemicals – For the FeIII–OOH intermediates, the anticancer drug activated bleomycin (BLM) acts as the non-heme Fe analog of compound 0 in heme (e.g., P450) chemistry. However BLM shows different reactivity: the low-spin (LS) FeIII–OOH can directly abstract a H atom from DNA. The LS and high-spin (HS) FeIII–OOHs have fundamentally different transition states. The LS transition state goes through a hydroxyl radical, but the HS transition state is activated for EAS without O–O cleavage. This activation is important in one class of NHFe enzymes that utilizes a HS FeIII–OOH intermediate in dioxygenation.

For FeIV═O intermediates, the LS form has a π-type FMO activated for attack perpendicular to the Fe–O bond. However, the HS form (present in the NHFe enzymes) has a π FMO activated perpendicular to the Fe–O bond and a σ FMO positioned along the Fe–O bond. For the NHFe enzymes, the presence of π and σ FMOs enables enzymatic control in determining the type of reactivity: EAS or H-atom extraction for one substrate with different enzymes and halogenation or hydroxylation for one enzyme with different substrates.