Volume 94, Issue 9

Photocatalytic carbon dioxide (CO 2 ) conversion has been recognized as one of the promising strategies for unraveling current environmental and energy problems attributed to the growing fossil fuel consumption of the human society because it can directly harness incident sunlight energy for converting waste CO 2 into valuable compounds. Increasing attention has been provoked to the semiconductor facet junction photocatalysts due to their unique feature in enhancing the photogenerated electron–hole pair utilization toward improving the photocatalytic CO 2 conversion performance. In the past decade, significant breakthroughs in the semiconductor facet junction photocatalysts for photocatalytic CO 2 conversion. In this review, we give a brief introduction on the development and the idea of the semiconductor facet junction photocatalysts. Then, the unique advantages of the semiconductor facet junction photocatalysts for photocatalytic CO 2 conversion are summarized. Subsequently, the recent development of semiconductor facet junction photocatalysts in photocatalytic CO 2 conversion is overviewed. We end this review by presenting the perspectives and challenges in this field for its future advancement toward practical applications. This review is expected to push forward the development of not only photocatalytic CO 2 conversion but also other energy and environmental photocatalytic applications.

This article summarizes the results of systematization of monitoring heterogeneous weather records (1961–2014) and interpretation of long-term observations of fluoride ion concentration in the snow cover of an area susceptible to emissions from an aluminum smelter in 2000–2014. The monitoring was carried out by the Federal Service for Hydrometeorology and Environmental Monitoring of Russia. The trends and correlation coefficients established in this study show that F concentration in the snow cover is affected by the following concurrent factors: distance from the emission source, amount of atmospheric precipitation, air temperature and duration of thaws during the period starting from formation of a stable snow cover to the date of sampling. These results emphasize the need to consider the weather factor in the future in the annual comparison of fluoride ion concentrations in the snow cover in order to increase the reliability of data on the changes in fluorine emissions from an aluminum smelter over many years.

The use of self-consistent terminology to describe polymerizations is important for litigation, patents, research and education. Imprecision in these areas can be both costly and confusing. To address this situation the International Union of Pure and Applied Chemistry (IUPAC) has made recommendations, which are summarized below. In the version shown as the supplementary material, references and hyperlinks lead to source documents; screen tips contain definitions published in IUPAC recommendations. More details can also be found in the IUPAC Purple Book. This guide is one of a series on terminology and nomenclature. Refer to the supplementary material for the complete and interactive version of this brief guide.

The IUPAC–IUGS joint Task Group “Isotopes in Geosciences” (TGIG) has evaluated the published literature on the half-lives of six long-lived, geologically relevant radioactive nuclides. Where conflicting literature estimates are present, it is necessary to first identify any systematic bias in accordance with metrological traceability and to exclude the biased estimates from further consideration. The TGIG recommends three robust half-life estimates: 49.61 ± 0.16 Ga for 87 Rb, corresponding to a decay constant λ ( 87 Rb) = (1.3972 ± 0.0045) × 10 −11  a −1 ; 106.25 ± 0.38 Ga for 147 Sm, and a corresponding decay constant λ ( 147 Sm) = (6.524 ± 0.024) × 10 −12  a −1 ; 4.4683 ± 0.0096 Ga for 238 U, i.e . a decay constant λ ( 238 U) = (1.55125 ± 0.00333) × 10 −10  a −1 . All cited uncertainties have a coverage factor k  = 2. For other radionuclides of Sm and U, no unambiguous consensus value can be endorsed at present by TGIG, which limits its evaluation to a status report highlighting unaccounted-for potential sources of bias. The improved repeatability of mass spectrometric measurements has revealed systematic bias effects that had been dismissed as subordinate in the past. These issues can only be resolved by future dedicated investigations.

Chain polymerizations are defined as chain reactions where the propagation steps occur by reaction between monomer(s) and active site(s) on the polymer chains with regeneration of the active site(s) at each step. Many forms of chain polymerization can be distinguished according to the mechanism of the propagation step (e.g., cyclopolymerization – when rings are formed, condensative chain polymerization – when propagation is a condensation reaction, group-transfer polymerization, polyinsertion, ring-opening polymerization – when rings are opened), whether they involve a termination step or not (e.g., living polymerization – when termination is absent, reversible-deactivation polymerization), whether a transfer step is involved (e.g., degenerative-transfer polymerization), and the type of chain carrier or active site (e.g., radical, ion, electrophile, nucleophile, coordination complex). The objective of this document is to provide a language for describing chain polymerizations that is both readily understandable and self-consistent, and which covers recent developments in this rapidly evolving field.