8-oxoguanine causes spontaneous de novo germline mutations in mice.

Spontaneous germline mutations generate genetic diversity in populations of sexually reproductive organisms, and are thus regarded as a driving force of evolution. However, the cause and mechanism remain unclear. 8-oxoguanine (8-oxoG) is a candidate molecule that causes germline mutations, because it makes DNA more prone to mutation and is constantly generated by reactive oxygen species in vivo. We show here that endogenous 8-oxoG caused de novo spontaneous and heritable G to T mutations in mice, which occurred at different stages in the germ cell lineage and were distributed throughout the chromosomes. Using exome analyses covering 40.9 Mb of mouse transcribed regions, we found increased frequencies of G to T mutations at a rate of 2 × 10(-7) mutations/base/generation in offspring of Mth1/Ogg1/Mutyh triple knockout (TOY-KO) mice, which accumulate 8-oxoG in the nuclear DNA of gonadal cells. The roles of MTH1, OGG1, and MUTYH are specific for the prevention of 8-oxoG-induced mutation, and 99% of the mutations observed in TOY-KO mice were G to T transversions caused by 8-oxoG; therefore, we concluded that 8-oxoG is a causative molecule for spontaneous and inheritable mutations of the germ lineage cells

Cellulose Triacetate (CTA) Hollow-Fiber (HF) Membranes for Sustainable Seawater Desalination: A Review

Cellulose triacetate (CTA)-based hollow fiber (HF) membrane is one of the commercially successful semipermeable membranes that has had a long progress since the time the excellent semi-permeable feature of cellulose-based polymers was found in 1957. Because of the reliable and excellent performances, especially for drinking water production from seawater, CTA-HFs have been widely used as reverse osmosis (RO) membranes, especially in arid regions. In this review, recent developments and research trends on CTA-HF membranes for seawater reverse osmosis (SWRO) plants were presented. A flux analytical model, an optimization strategy for chlorine injection without losing salt rejection performance, and a module of current high performance CTA RO membranes along with its plant operation data were updated in this paper. Furthermore, a newly developed CTA-HF membrane for brine concentration (BC) application (called BC membrane) was also addressed. Finally, RO/BC hybrid operation was introduced as an effective SWRO desalination technique that enables minimizing the volume of brine disposal from the RO plant by increasing the recovery ratio and the subsequent amount of produced freshwater, without an additional energy input

Single-Crystal-like Durable LiNiO₂ Positive Electrode Materials for Lithium-Ion Batteries

Cobalt-free, nickel-rich positive electrode materials are attracting attention because of their high energy density and low cost, and the ultimate material is LiNiO2 (LNO). One of the issues of LNO is its poor cycling performance, which needs to be improved. Referring to a current study to show the improved stability of single-crystal-like high-nickelate materials, we fabricated single-crystal-like (SC-) LNO and the counterpart polycrystalline (PC-) LNO samples and examined their electrochemical properties. SC-LNO was nearly single-crystal-like, as proved by electron backscattering diffraction, and had more cation mixing than PC-LNO. Cycle tests under 2.5–4.2 V, a 2C rate, and 45 °C conditions showed that the capacity retention of SC-LNO after 500 cycles (63.5%) was significantly better than that of PC-LNO (36.1%) under the same conditions and even better than that of PC-LNO cycled between 2.5 and 4.15 V (50.7%) with the same initial capacity as SC-LNO. The derivative dQ/dV profile of PC-LNO became featureless during a long cycling time, suggesting the progress of cation mixing in PC-LNO, whereas that of SC-LNO was better maintained, in accordance with the serious particle cracking in PC-LNO and no particle cracking found in SC-LNO as the result of post-mortem analysis after 500 cycles. The electrode impedance increase of PC-LNO was considerably larger than that of SC-LNO, corresponding to the formation of rock-salt phases at the surface and the cracked interface of the PC-LNO and the formation of scattered spinel-like phases with a thick cathode electrolyte interphase at the surface of SC-LNO. Accordingly, SC-LNO is shown to be less degraded in both the bulk nature (stable dQ/dV profile and no cracking) and the surface characteristics (high rate capacity maintenance and less impedance increase), suggesting the importance of single-crystal-like particles as durable electrode materials