High-Pressure Synthesis, Crystal Structure, and Unusual Valence State of Novel Perovskite Oxide CaCu₃Rh₄O₁₂

A novel perovskite oxide, CaCu₃Rh₄O₁₂, has been synthesized under high-pressure and high-temperature conditions (15 GPa and 1273 K). Rietveld refinement of synchrotron X-ray powder diffraction data indicates that this compound crystallizes in a cubic AA′₃B₄O₁₂-type perovskite structure. Synchrotron X-ray absorption and photoemission spectroscopy measurements reveal that the Cu and Rh valences are nearly trivalent. The spectroscopic analysis based on calculations suggests that the appropriate ionic model of this compound is Ca²⁺Cu^∼2.8+₃Rh^∼3.4+₄O₁₂, as opposed to the conventional Ca²⁺Cu²⁺₃Rh⁴⁺₄O₁₂. The uncommon valence state of this compound is attributed to the relative energy levels of the Cu 3d and Rh 4d orbitals, in which the large crystal-field splitting energy of the Rh 4d orbitals is substantial

A Highly Accurate Inclusive Cancer Screening Test Using <i>Caenorhabditis elegans</i> Scent Detection

<div><p>Early detection and treatment are of vital importance to the successful eradication of various cancers, and development of economical and non-invasive novel cancer screening systems is critical. Previous reports using canine scent detection demonstrated the existence of cancer-specific odours. However, it is difficult to introduce canine scent recognition into clinical practice because of the need to maintain accuracy. In this study, we developed a Nematode Scent Detection Test (NSDT) using <i>Caenorhabditis elegans</i> to provide a novel highly accurate cancer detection system that is economical, painless, rapid and convenient. We demonstrated wild-type <i>C</i>. <i>elegans</i> displayed attractive chemotaxis towards human cancer cell secretions, cancer tissues and urine from cancer patients but avoided control urine; in parallel, the response of the olfactory neurons of <i>C</i>. <i>elegans</i> to the urine from cancer patients was significantly stronger than to control urine. In contrast, G protein α mutants and olfactory neurons-ablated animals were not attracted to cancer patient urine, suggesting that <i>C</i>. <i>elegans</i> senses odours in urine. We tested 242 samples to measure the performance of the NSDT, and found the sensitivity was 95.8%; this is markedly higher than that of other existing tumour markers. Furthermore, the specificity was 95.0%. Importantly, this test was able to diagnose various cancer types tested at the early stage (stage 0 or 1). To conclude, <i>C</i>. <i>elegans</i> scent-based analyses might provide a new strategy to detect and study disease-associated scents.</p></div

<i>C</i>. <i>elegans</i> can respond to cancer cell culture medium and cancer tissue, and detect cancer smells in human urine.

<p>(A) Chemotaxis of wild-type <i>C</i>. <i>elegans</i> to 10^-6 and 10^-7 dilutions of MEM, EMEM or RPMI medium only, or culture medium from fibroblast (KMST-6 and CCD-112CoN), colorectal cancer (SW480, COLO201 and COLO205), breast cancer (MCF7) or gastric cancer (NUGC4, MKN1 and MKN7) cells (n ≥ 5 assays). (B) Chemotaxis of wild type and <i>odr-3</i> mutants (n ≥ 5 assays) in response to a 10^-6 dilution of conditioned culture medium from colorectal, breast or gastric cancer cells. (C) Chemotaxis of wild type to 10^-2, 10^-3 and 10^-4 dilutions of saline with normal and cancer tissue (n ≥ 5 assays). (D) Chemotaxis to normal and cancer tissue by wild-type and <i>odr-3</i> mutants (n ≥ 5 assays). (E) Chemotaxis of wild type to human urine samples from control subjects (blue bars; c1–c10) or cancer patients (orange bars; p1–p20) at 10^-1 dilution (n = 5 assays). (F) Chemotaxis to urine from cancer patients by wild-type and <i>odr-3</i> mutants at 10^-1 dilution (n ≥ 6 assays). Error bars represent SEM. Significant differences from control samples are indicated by * (<i>P</i> < 0.05); ** (<i>P</i> < 0.01); *** (<i>P</i> < 0.001) by Dunnett’s tests (A) or Student’s <i>t</i>-tests (B, C, D, F). † indicates a significant difference (<i>P</i> < 0.05) by Student’s <i>t</i>-tests (A).</p

NSDT of 242 urine samples.

<p>Box plots (A) and dot plots (B) of chemotactic responses of wild-type <i>C</i>. <i>elegans</i> to urine samples from control subjects (n = 218) or cancer patients (n = 24). Whiskers indicate 10th and 90th percentiles.</p

A‑Site and B‑Site Charge Orderings in an <i>s–d</i> Level Controlled Perovskite Oxide PbCoO₃

Perovskite PbCoO₃ synthesized at 12 GPa was found to have an unusual charge distribution of Pb²⁺Pb⁴⁺₃Co²⁺₂Co³⁺₂O₁₂ with charge orderings in both the A and B sites of perovskite ABO₃. Comprehensive studies using density functional theory (DFT) calculation, electron diffraction (ED), synchrotron X-ray diffraction (SXRD), neutron powder diffraction (NPD), hard X-ray photoemission spectroscopy (HAXPES), soft X-ray absorption spectroscopy (XAS), and measurements of specific heat as well as magnetic and electrical properties provide evidence of lead ion and cobalt ion charge ordering leading to Pb²⁺Pb⁴⁺₃Co²⁺₂Co³⁺₂O₁₂ quadruple perovskite structure. It is shown that the average valence distribution of Pb^3.5+Co^2.5+O₃ between Pb³⁺Cr³⁺O₃ and Pb⁴⁺Ni²⁺O₃ can be stabilized by tuning the energy levels of Pb 6<i>s</i> and transition metal 3<i>d</i> orbitals