Dopant‐induced helical conformations of polyaniline (PANI) nanofibers are presented. Right‐ and left‐handed helical nanofibers of conducting PANI are produced using respectively D‐ and L‐camphorsulfonic acid as the dopant, it is reported, as proved by the mirror‐image chiral dichroism spectra (see figure). The authors suggest a mechanism for the formation of nanofibrillar bundles of helical nanofibers.

Three new lead-free organic–inorganic metal halides (OIMHs) (C7H8N3)3InX6·H2O (X = Cl, Br) and (C7H8N3)2SbBr5 were synthesized. First-principles calculations indicate that the highest occupied molecular orbitals (HOMOs) of the two In-based OIMHs are constituted of π orbitals from [C7H8N3]+ spacers. (C7H8N3)3InX6·H2O (X = Cl, Br) shows an indirect optical gap, which may result from this organic-contributed band edge. Despite the indirect-gap nature with extra phonon process during absorption, the photoluminescence of (C7H8N3)3InBr6·H2O can still be significantly enhanced through Sb doping, with the internal photoluminescence quantum yields (PLQY) increased 10-fold from 5% to 52%. A white light-emitting diode (WLED) was fabricated based on (C7H8N3)3InBr6·H2O:Sb3+, exhibiting a high color-rendering index of 90. Our work provides new systems to deeply understand the principles for organic spacer choice to obtain the 0D metal OIMHs with specific band structure and also the significant enhancement of luminescence performance by chemical doping.

Microbial enzymes during solid-state fermentation (SSF), which play important roles in the food, chemical, pharmaceutical and environmental fields, remain relatively unknown. In this work, the microbial communities and enzymes in SSF of Pu-erh tea, a well-known traditional Chinese tea, were investigated by integrated metagenomics/metaproteomics approach. The dominant bacteria and fungi were identified as Proteobacteria (48.42%) and Aspergillus (94.98%), through pyrosequencing-based analyses of the bacterial 16S and fungal 18S rRNA genes, respectively. In total, 335 proteins with at least two unique peptides were identified and classified into 28 Biological Processes and 35 Molecular Function categories using a metaproteomics analysis. The integration of metagenomics and metaproteomics data demonstrated that Aspergillus was dominant fungus and major host of identified proteins (50.45%). Enzymes involved in the degradation of the plant cell wall were identified and associated with the soft-rotting of tea leaves. Peroxiredoxins, catalase and peroxidases were associated with the oxidation of catechins. In conclusion, this work greatly advances our understanding of the SSF of Pu-erh tea and provides a powerful tool for studying SSF mechanisms, especially in relation to the microbial communities present.

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Two previous studies have reported that pu-erh tea contains a high level of γ-aminobutyric acid (GABA), which is the major inhibitory neurotransmitter in the central nervous system and has several physiological functions. However, two other researchers have demonstrated that the GABA content of several pu-erh teas was low. Due to the high value and health benefits of GABA, analysis of mass-produced pu-erh tea is necessary to determine whether it is actually enriched with GABA. A high-performance liquid chromatography (HPLC) method was developed for the determination of GABA in tea, the results of which were verified by amino acid analysis using an Amino Acid Analyzer (AAA). A total of 114 samples of various types of Chinese tea, including 62 pu-erh teas, 13 green teas, 8 oolong teas, 8 black teas, 3 white teas, 4 GABA teas, and 16 process samples from two industrial fermentations of pu-erh tea (including the raw material and the first to seventh turnings), were analyzed using HPLC. Statistical analysis demonstrated that the GABA content in pu-erh tea was significantly lower than that in other types of tea (p < 0.05) and that the GABA content decreased during industrial fermentation of pu-erh tea (p < 0.05). This mass analysis and comparison suggested GABA was not a major bioactive constituent and resolved the disagreement GABA content in pu-erh tea. In addition, the GABA content in white tea was found to be significantly higher than that in the other types of tea (p < 0.05), leading to the possibility of producing GABA-enriched white tea.

The rate of visible-light-driven photocatalytic hydrogen production from water splitting is greatly enhanced from zero to 555 mmol h À1 g À1 through hybridizing a suitable amount of CdS particles onto the micro-SiC surface. It suggests that the hybridization is responsible for lowering the surface activation energy of SiC and well-connected SiC/ CdS interfaces serve as active sites for photocatalytic reactions, leading to this significant enhancement. The self-corrosion of CdS is simultaneously avoided and the composites show high stability. Our results demonstrate that SiC powder with high electron mobility, low cost, availability of large amounts and environmental friendliness has potential to become an efficient catalyst that might find practical applications.Since the pioneering work by Fujishima and Honda in 1972, 1 compound semiconductors have become a major class of materials acting as photocatalysts for conversion of solar energy into hydrogen by splitting water. 2-7 To date, a number of criteria have been established to enhance the conversion efficiency of a semiconductor photocatalyst. 8-11 For instance, a suitable band gap required to absorb the solar energy as much as possible, a low recombination rate of photogenerated holes and electrons, good chemical stability to water corrosion, good crystallinity and so on. Semiconductor catalysts under investigation, however, seldom meet all the above standards and exhibit desirable photocatalytic hydrogen evolution (PHE) activity. 12,13 Instead, they rarely outperform the traditional TiO 2 -based catalyst in conversion efficiency though the latter only utilizes 4% of solar energy owing to its wide band gap. The semiconductor materials with high solar-energy conversion efficiency that can be used practically for water splitting still need to be further explored.Silicon carbide, a well-known semiconductor, is nding more and more applications in power electronics, light emitting diodes and radio frequency devices in recent years due to its excellent electronic and thermal properties. 14-16 On the other hand, silicon carbide powder is one of the most useful abrasives in the industry due to its hardness, low cost and environmental friendliness. This material has a band gap of 2.3-3.3 eV (which of b-SiC is 2.4 eV), and the bottom of its conduction band (CB) lies above the reduction potential of H + to H 2 , which is more negative than the CB of most semiconductors. 17-19 Silicon carbide is an ideal visible-light-driven photocatalyst in terms of appropriate band gap and CB position. Moreover, its high charge-carrier mobility can offer an opportunity to quickly shuttle the photogenerated carriers before their recombination from the bulk to the surface of the photocatalyst. 20 In contrast, the SiC powder actually exhibits very weak photocatalytic activity, if any, under light illumination with wavelength from the visible to ultraviolet range. 21,22 Solar water splitting, however, can occur over SiC if it is tailored into the forms of nano-sized particles, wires or rod...

Functional materials showing both negative thermal expansion (NTE) and physical performance, such as ferroelectricity and magnetism, have been extensively explored in the past decade. However, among ferroelectrics a remarkable NTE was only found in perovskite-type PbTiO3-based compounds. In this work, a large NTE of -4.7 × 10(-5) K(-1) is obtained in the non-perovskite lead-free ferroelectric Sn2P2S6 from 243 K to TC (338 K). Structure refinements and first-principle calculations reveal the effects of the Sn(ii) 5s-S 3p interaction on spontaneous polarization and its correlation with NTE. Then the mechanism of spontaneous volume ferroelectrostriction (SVFS) is verified and it could well elucidate the nature of NTE in ferroelectric Sn2P2S6. This is the first case to demonstrate the unusual NTE behavior by SVFS in a non-perovskite lead-free ferroelectric material.

Microbes are thought to have key roles in the development of the special properties of post-fermented pu-erh tea (pu-erh shucha), a well-known traditional Chinese tea; however, little is known about the bacteria during the fermentation. In this work, the structure and dynamics of the bacterial community involved in the production of pu-erh shucha were investigated using 16S rRNA gene clone libraries constructed from samples collected on days zero (LD-0), 5 (LD-5), 10 (LD-10), 15 (LD-15) and 20 (LD-20) of the fermentation. A total of 747 sequences with individual clone library containing 115-174 sequences and 4-20 unique operational taxonomic units (OTUs) were obtained. These OTUs were grouped into four phyla (Actinobacteria, Bacteroidetes, Firmicutes and Proteobacteria) and further identified as members of 10 families, such as Alcaligenaceae, Bacillaceae, Enterobacteriaceae, etc. The dominant bacteria were Enterobacteriaceae in the raw material (LD-0) and in the initial stages of fermentation (LD-5 and LD-10), which changed to Bacillaceae at the last stages of fermentation (LD-15 and LD-20) at a temperature of 40-60 °C. It is interesting that the dominant OTUs in libraries LD-15 and LD-20 were very closely related to Bacillus coagulans, which is a safe thermoduric probiotic. Together the bacterial diversity and dynamics during a fermentation of pu-erh shucha were demonstrated, and a worthy clue for artificial inoculation of B. coagulans to improve the health benefits of pu-erh shucha or produce probiotic pu-erh tea were provided.