Continuous strain tuning of oxygen evolution catalysts with anisotropic thermal expansion.

Compressive strain, downshifting the d-band center of transition metal oxides, is an effective way to accelerate the sluggish kinetics of oxygen evolution reaction (OER) for water electrolysis. Here, we find that anisotropic thermal expansion can produce compressive strains of the IrO6 octahedron in Sr2IrO4 catalyst, thus downshifting its d-band center. Different from the previous strategies to create constant strains in the crystals, the thermal-triggered compressive strains can be real-timely tuned by varying temperature. As a result of the thermal strain accelerating OER kinetics, the Sr2IrO4 exhibits the nonlinear lnjo - T-1 (jo, exchange current density; T, absolute temperature) Arrhenius relationship, resulting from the thermally induced low-barrier electron transfer in the presence of thermal compressive strains. Our results verify that the thermal field can be utilized to manipulate the electronic states of Sr2IrO4 via thermal compressive strains downshifting the d-band center, significantly accelerating the OER kinetics, beyond the traditional thermal diffusion effects.

High-quality chromosome-level genome assembly and multi-omics analysis of rosemary (Salvia rosmarinus) reveals new insights into the environmental and genome adaptation.

High-quality genome of rosemary (Salvia rosmarinus) represents a valuable resource and tool for understanding genome evolution and environmental adaptation as well as its genetic improvement. However, the existing rosemary genome did not provide insights into the relationship between antioxidant components and environmental adaptability. In this study, by employing Nanopore sequencing and Hi-C technologies, a total of 1.17 Gb (97.96%) genome sequences were mapped to 12 chromosomes with 46 121 protein-coding genes and 1265 non-coding RNA genes. Comparative genome analysis reveals that rosemary had a closely genetic relationship with Salvia splendens and Salvia miltiorrhiza, and it diverged from them approximately 33.7 million years ago (MYA), and one whole-genome duplication occurred around 28.3 MYA in rosemary genome. Among all identified rosemary genes, 1918 gene families were expanded, 35 of which are involved in the biosynthesis of antioxidant components. These expanded gene families enhance the ability of rosemary adaptation to adverse environments. Multi-omics (integrated transcriptome and metabolome) analysis showed the tissue-specific distribution of antioxidant components related to environmental adaptation. During the drought, heat and salt stress treatments, 36 genes in the biosynthesis pathways of carnosic acid, rosmarinic acid and flavonoids were up-regulated, illustrating the important role of these antioxidant components in responding to abiotic stresses by adjusting ROS homeostasis. Moreover, cooperating with the photosynthesis, substance and energy metabolism, protein and ion balance, the collaborative system maintained cell stability and improved the ability of rosemary against harsh environment. This study provides a genomic data platform for gene discovery and precision breeding in rosemary. Our results also provide new insights into the adaptive evolution of rosemary and the contribution of antioxidant components in resistance to harsh environments.

Thermal suppression of charge disproportionation accelerates interface electron transfer of water electrolysis.

The sluggish electron transfer kinetics in electrode polarization driven oxygen evolution reaction (OER) result in big energy barriers of water electrolysis. Accelerating the electron transfer at the electrolyte/catalytic layer/catalyst bulk interfaces is an efficient way to improve electricity-to-hydrogen efficiency. Herein, the electron transfer at the Sr3Fe2O7@SrFeOOH bulk/catalytic layer interface is accelerated by heating to eliminate charge disproportionation from Fe4+ to Fe3+ and Fe5+ in Sr3Fe2O7, a physical effect to thermally stabilize high-spin Fe4+ (t2g3eg1), providing available orbitals as electron transfer channels without pairing energy. As a result of thermal-induced changes in electronic states via thermal comproportionation, a sudden increase in OER performances was achieved as heating to completely suppress charge disproportionation, breaking a linear Arrhenius relationship. The strategy of regulating electronic states by thermal field opens a broad avenue to overcome the electron transfer barriers in water splitting.

A new species of Cotoneaster (Rosaceae) from western Sichuan, China.

Cotoneasterdensiflorus, a new species of Rosaceae from western Sichuan, China, is described and illustrated. Morphologically, we inferred that the new species belongs to CotoneasterSer.Salicifolii sensu Yü et al. (1974) in the Flora of China and Fryer and Hylmö (2009). This species is most similar to C.salicifolius, but differs in its leaf blade of ovate-lanceolate to obovate shape (vs. elliptic-oblong to ovate-lanceolate), smaller length-width ratio of 2.37 ± 0.31 (vs. 3.17 ± 0.32), slightly conduplicate (vs. not conduplicate), less lateral veins of 6-8 pairs (vs. 12-16 pairs), upper surface slightly rugose (vs. rugose), leaf margin plane (vs. revolute), lower surface densely grey tomentose (vs. grey tomentose, with bloom), greater corolla diameter of 7-9 mm (vs. 5-6 mm), styles 2 (vs. 2-3), pyrenes 2 (vs. 2-3), larger pollen grains P/E values of 2.05 ± 0.12 (vs. 1.19 ± 0.05) and leaf epidermis type W (vs. type I). Based on phylogenetic analysis of the whole chloroplast genome, C.densiflorus is sister to C.rhytidophyllus, but distantly related to C.salicifolius.

Heat-Induced Magnetic Transition for Water Electrolysis on NiFeN@NiFeOOH Core-Shell Assembly.

The overpotentials of electrochemical oxygen evolution reaction (OER) inherently originate from high electron transfer barriers of the redox couple driven water oxidation. Here, we propose a heat-induced magnetic transition strategy to reduce the spin-related electron transfer barriers. Coupling heat into electrochemical OER on a ferro-antiferromagnetic core-shell NiFeN@NiFeOOH, the heat-induced ferro-to-paramagnetic transition for NiFeN core at 55 °C and antiferro-to-paramagnetic transition for NiFeOOH shell at 70 °C significantly accelerate and accordingly achieve a cascaded Ni2+/Ni3+ driven water oxidation reaction. In addition, paramagnetic Niδ+ (δ ≥ 3) in NiFeN@NiFeOOH can thermochemically react with water to produce oxygen. The heat-induced magnetic transition concomitantly triggers the electrochemical redox couple driven water oxidation and the thermochemical water oxidation due to that heat-induced paramagnetic spin reduces the barriers of electricity driving the spin flipping. Our findings offer new insights into constructing the heat-electricity coupling water splitting.

High-valence chromium accelerated interface electron transfer for water oxidation.

An effective pathway to cope with the sluggish oxygen evolution reaction (OER) is to accelerate the electron transfer kinetics. Transition metal with high valence states doping can accelerate the reaction kinetics to afford high inherent activity. Herein, a novel trimetallic NiFeCr nanoalloy as an OER electrocatalyst is synthesized by replacing partial Fe in the Ni3Fe alloy with Cr. In the OER process, Cr leached from the surface layer of the NiFeCr alloy to form a core-shell NiFeCr@NiFeOOH structure. The electrons from the OER intermediates were significantly accelerated by the high-valence Cr6+ as an electron acceptor at the core-shell interface. As a result, NiFeCr@NiFeOOH exhibited excellent OER performances with a low overpotential of 209 mV at 25 mA cm-2 in 1.0 M KOH on conductive carbon paper, outperforming the Ni3Fe alloy without Cr doping. Our work provides a new strategy to design and synthesize the NiFe-based alloy with high OER activity.

Quantum dot-based electrochemical biosensor for stripping voltammetric detection of telomerase at the single-cell level.

Human telomerase is responsible for the maintenance of chromosome end structures and is a valuable biomarker for malignant growth. However, the accurate measurement of telomerase activity at the single-cell level has remained a great challenge. Here we develop a simple quantum dot (QD)-based electrochemical biosensor for stripping voltammetric detection of telomerase activity at the single-cell level. We designed a thiol-modified capture DNA which may be immobilized on the gold electrode by the gold-sulfur bond. The presence of telomerase enables the addition of the telomere repeats of (TTAGGG)n to the 3' end of the primer, accompanied by the incorporation of abundant biotins in the extension product with the assistance of the biotin-tagged dATP. The subsequent hybridization of extension product with the capture DNA and the addition of streptavidin-coated QDs induce the assembly of large amounts of QDs onto the electrode via specific biotin-streptavidin binding. After the acidic dissolution of QDs, the released Cd (II) can be simply quantified by anodic stripping voltammetry (ASV). Due to the introduction of large amounts of QDs by telomerase-induced primer extension reaction and the synergistic signal amplification induced by the release of Cd (II) from the QDs, this biosensor can detect telomerase activity at the single-cell level without the involvement of any thermal cycling and extra enzymes for signal amplification. Moreover, this assay exhibits a large dynamic range over four orders of magnitude and it is very simple without the involvement of specific hairpin probe design and complicated labelling, holding great potential in point-of-need testing.

An ultrasensitive electrochemical biosensor for polynucleotide kinase assay based on gold nanoparticle-mediated lambda exonuclease cleavage-induced signal amplification.

Polynucleotide kinase (PNK) plays an essential role in cellular nucleic acid metabolism and the cellular response to DNA damage. However, conventional methods for PNK assay suffer from low sensitivity and involve multiple steps. Herein, we develop a simply electrochemical method for sensitive detection of PNK activity on the basis of Au nanoparticle (AuNP)-mediated lambda exonuclease cleavage-induced signal amplification. We use [Ru(NH3)6]3+ as the electrochemically active indicator and design two DNA strands (i.e., strand 1 and strand 2) to sense PNK. The assembly of strand 2 on the AuNP surface leads to the formation of AuNP-strand 2 conjugates which can be subsequently immobilized on the gold electrode through the hybridization of strand 1 with strand 2 for the generation of a high electrochemical signal. The presence of PNK induces the phosphorylation of the strand 2-strand 1 hybrid and the subsequent cleavage of double-stranded DNA (dsDNA) by lambda exonuclease, resulting in the release of AuNP-strand 2 conjugates and [Ru(NH3)6]3+ from the gold electrode surface and consequently the decrease of electrochemical signal. The PNK activity can be simply monitored by the measurement of [Ru(NH3)6]3+ peak current signal. This assay is very sensitive with a detection limit of as low as 7.762 × 10-4UmL-1 and exhibits a large dynamic range from 0.001 to 10UmL-1. Moreover, this method can be used to screen the PNK inhibitors, and it shows excellent performance in real sample analysis, thus holding great potential for further applications in biological researches and clinic diagnosis.

A reusable ratiometric electrochemical biosensor on the basis of the binding of methylene blue to DNA with alternating AT base sequence for sensitive detection of adenosine.

We develop a reusable ratiometric electrochemical biosensor on the basis of the binding of methylene blue (MB) to DNA with alternating AT base sequence for sensitive detection of adenosine. We design a strand 1 with MB-modified thymine (T) base in the proximal 3' termini as the capture probe for its immobilization on the gold electrode and a 3' termini ferrocene (Fc)-modified aptamer for the recognition of adenosine. The hybridization of strand 1 with the aptamer leads to the formation of a double-stranded DNA (dsDNA) and consequently the away of MB from the electrode surface and the close of Fc to the electrode surface, generating a small value of IMB/IFc (IMB and IFc are the peak currents of MB and Fc, respectively). In the presence of adenosine, its binding with the aptamer induces the release of Fc from the electrode surface and the close of MB to the electrode surface, generating a large value of IMB/IFc. As a result, adenosine may be accurately quantified by the measurement of ratiometric signal (IMB/IFc). This ratiometric electrochemical biosensor can be simply fabricated and exhibits high sensitivity with a limit of detection of as low as 90.8pM and a large dynamic range from 0.1nM to 100µM. Moreover, this biosensor demonstrates good performance with excellent selectivity, regeneration capability, high reliability and good reproducibility, and may become a universal platform for the detection of various biomolecules which can be recognized by aptamers, holding great potential for further applications in biomedical research and clinical diagnosis.

Pharmacogenetic testing through the direct-to-consumer genetic testing company 23andMe.

BACKGROUND: Rapid advances in scientific research have led to an increase in public awareness of genetic testing and pharmacogenetics. Direct-to-consumer (DTC) genetic testing companies, such as 23andMe, allow consumers to access their genetic information directly through an online service without the involvement of healthcare professionals. Here, we evaluate the clinical relevance of pharmacogenetic tests reported by 23andMe in their UK tests. METHODS: The research papers listed under each 23andMe report were evaluated, extracting information on effect size, sample size and ethnicity. A wider literature search was performed to provide a fuller assessment of the pharmacogenetic test and variants were matched to FDA recommendations. Additional evidence from CPIC guidelines, PharmGKB, and Dutch Pharmacogenetics Working Group was reviewed to determine current clinical practice. The value of the tests across ethnic groups was determined, including information on linkage disequilibrium between the tested SNP and causal pharmacogenetic variant, where relevant. RESULTS: 23andMe offers 12 pharmacogenetic tests to their UK customers, some of which are in standard clinical practice, and others which are less widely applied. The clinical validity and clinical utility varies extensively between tests. The variants tested are likely to have different degrees of sensitivity due to different risk allele frequencies and linkage disequilibrium patterns across populations. The clinical relevance depends on the ethnicity of the individual and variability of pharmacogenetic markers. Further research is required to determine causal variants and provide more complete assessment of drug response and side effects. CONCLUSION: 23andMe reports provide some useful pharmacogenetics information, mirroring clinical tests that are in standard use. Other tests are unspecific, providing limited guidance and may not be useful for patients without professional interpretation. Nevertheless, DTC companies like 23andMe act as a powerful intermediate step to integrate pharmacogenetic testing into clinical practice.

A sensitive ratiometric electrochemical biosensor based on DNA four-way junction formation and enzyme-assisted recycling amplification.

A simple ratiometric electrochemical biosensor is developed for sensitive detection of target DNA based on DNA four-way junction (DNA-4WJ) formation and enzyme-assisted recycling amplification. This biosensor can be easily fabricated by a one-step assembly of ratiometric probes and simply performed by a one-step incubation procedure. In the presence of target DNA, two unmodified DNA oligonucleotides may cooperatively hybridize with a hairpin probe in the triple-helix molecular beacon (THMB) to form a DNA-4WJ, which may cause conformational transduction and induce the change in the distance between two redox labeling probes and the electrode surface. The subsequent recognition and cleavage of DNA-4WJ quadripartite complexes by RNase HII may result in significant signal amplification. Due to the introduction of DNA-4WJ formation, enzyme-assisted recycling amplification and ratiometric measurement, this biosensor exhibits high sensitivity with a detection limit as low as 0.063 pM and a long dynamic range from 0.1 pM to 100 nM. Moreover, this biosensor demonstrates good performance with excellent selectivity, high reliability and good reproducibility, holding great potential for further applications in biomedical research and clinical diagnostics.