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Figure S1. (A) Quantified presentation of ZEB1, ELK3 and CDH1 expression with the dataset of 49 breast cancer cell lines obtained from the University of California Santa Cruz (UCSC) Xena Browser (http://xena.ucsc.edu/). (B) Correlation efficiency analysis of ZEB1/ELK3, CHD1/ELK3 and CDH1/ZEB1 expression in 49 breast cancer cell lines. The data of triple negative breast cancer cell lines are presented as grey color. Figure S2. Correlation analysis of ELK3 and ZEB1 protein expression in 6 breast cell lines of figure 1C. Immunoblot band intensity of ELK3 and ZEB1 is normalized to that of GAPDH. The data of basal type of breast cancer cell lines are presented as red dots. Figure S3. The effect of ELK3 suppression on the expression of EMT-related transcription factors. Figure S4. Survival analysis mediated by the expression of ELK3 and ZEB1. Figure S5. The transcriptional repressor activity of the ELK3 deletion mutant on the E-cadherin promoter. Figure S6. ZEB1-independent transcriptional repressor activity of ELK3 on the E-cadherin promoter. Figure S7. Correlation of ELK3 and other EMT related transcription factors in breast cancer patients. The Cancer Genome Atlas (TCGA) database was analyzed by GenExMiner 3.0. Table S1. Plasmids used in this study Table S2. siRNAs used in this study Table S3. Oligomers used in this study Table S4. Antibodies used in this study

ZEB1 has intrinsic oncogenic functions that control the epithelial-to-mesenchymal transition (EMT) of cancer cells, impacting tumorigenesis from its earliest stages. By integrating microenvironment signals and being implicated in feedback regulatory loops, ZEB1 appears to be a central switch that determines EMT and metastasis of cancer cells. Here, we found that ZEB1 collaborates with ELK3, a ternary complex factor belonging to the ETS family, to repress E-cadherin expression. ZEB1 functions as a transcriptional activator of ELK3. We first identified that ELK3 and ZEB1 have a positively correlated expression in breast cancer cells by using multiple databases for correlation analysis. Molecular analysis revealed that ZEB1 functions as a transcriptional activator of ELK3 expression. GST pull-down assay and coimmunoprecipitation analysis of wild-type or domain deletion mutants of ZEB1 and ELK3 showed that these 2 proteins directly bound each other. Furthermore, we demonstrated that ZEB1 and ELK3 collaborate to repress the expression of E-cadherin, a representative protein that initiates EMT. Our finding suggested that ELK3 is a novel factor of the ZEB1/E-cadherin axis in triple-negative breast cancer cells.Implications:ELK3 is a novel factor in the ZEB1/E-cadherin axis and ZEB1 has a dual role in ELK3 as a transcriptional activator and as a collaborator to repress E-cadherin expression in triple-negative breast cancer cells.

Supplementary Methods and References

Supplementary Figure S1. Sequence Alignment of VEGF-Grab1, VEGF-Grab3, and VEGF-Trap; Supplementary Figure S2. Analysis of N-linked Glycosylation for VEGF-Grabs and VEGF-Trap; Supplementary Figure S3. Analysis of O-linked Glycosylation in VEGF-Grab1; Supplementary Figure S4. VEGF-Grab3 displays low binding to tumor ECM; Supplementary Figure S5. Pharmacokinetic profile of VEGF-Grab1 and VEGF-Grab3; Supplementary Figure S6. Tissue accumulation of VEGF-Trap and VEGF-Grab3; Supplementary Figure S7. VEGF-Grabs or VEGF-Trap have no effects on VEGFR2 signalling, EC survival, migration, and tube formation in the absence of VEGFA; Supplementary Figure S8. Dose-dependent Inhibition of VEGFR2 Signalling with Anti-VEGF Therapy; Supplementary Figure S9. Histologic Analyses of Vital Organs after Anti-VEGF Therapy; Supplementary Figure S10. VEGF-Grab effectively suppresses the growth of established bulky macroscopic tumors; Supplementary Figure S11. Histological analyses of the kidney and liver after dose dependent anti-VEGF therapy; Supplementary Figure S12. Combination Therapy of VEGF-Grab3 and Cisplatin Enhances Intratumoral Apoptosis; Supplementary Table S1. Primer sequences for site-directed mutagenesis; Supplementary Table S2. Primer sequences for Quantitative Real Time PCR; Supplementary Table S3. Antibodies.

Long noncoding RNAs (lncRNAs) act as transcriptional regulators in plants and animals. To date, they have been reported to regulate various biological processes, such as phosphate homeostasis, grain yield, and fertility in rice (Oryza sativa L.). However, the lncRNAs involved in abiotic stress responses remain poorly identified in rice. In this study, we analyzed the expression profiles of lncRNAs using public rice transcriptome datasets derived from abiotic stress-treated samples. We found that the expression of thousands of rice lncRNAs was significantly altered in the shoot and root tissues under different abiotic stresses (drought, high salinity, low temperature, and abscisic acid). We selected six novel drought-induced lncRNAs (DRILs, specifically DRIL1 to DRIL6) for further study. Real-time polymerase chain reaction analysis revealed the differential expression patterns of these DRILs under various stress conditions. The expression of abiotic stress-responsive genes was upregulated in the protoplasts by transiently overexpressed DRIL1 and DRIL4. Therefore, DRILs may be involved in the transcriptional regulation of abiotic stress-responsive genes in rice.

The efficient nonviral delivery of nucleic acids into the cytoplasm is needed to fully realize the potential of gene therapy. Although cationic lipids and nanoparticles have been widely used to improve the intracellular delivery of nucleic acids, they suffer from cytotoxicity and poor endosomal escape, thus limiting the transfection efficacy. Here, we developed a photothermal transfection platform for efficient and biosafe intracellular delivery of nucleic acids. Photothermal transfection was carried out by irradiation of cells co-treated with Lipofectamine-plasmid DNA complexes and PEGylated gold nanorods (GNRs) using an NIR laser for 30 min and subsequent incubation of the cells for 30 min without laser irradiation. Compared to conventional Lipofectamine-based transfection, our photothermal transfection platform significantly improved the transfection efficiency in difficult-to-transfect human primary cells including human dermal fibroblasts while maintaining the cell viability. The photothermal heating did not leave the GNRs inside the cell, thereby minimizing the cellular damage. Furthermore, the photothermal transfection platform showed superior genome editing abilities (both gene cleavage and insertion) in human dermal fibroblasts than conventional Lipofectamine-based transfection.

Macrophages have been associated with drug response and resistance in diverse settings, thus raising the possibility of using macrophage imaging as a companion diagnostic to inform personalized patient treatment strategies. Nanoparticle-based contrast agents are especially promising because they efficiently deliver fluorescent, magnetic, and/or radionuclide labels by leveraging the intrinsic capacity of macrophages to accumulate nanomaterials in their role as professional phagocytes. Unfortunately, current clinical imaging modalities are limited in their ability to quantify broad molecular programs that may explain (a) which particular cell subsets a given imaging agent is actually labeling, and (b) what mechanistic role those cells play in promoting drug response or resistance. Highly multiplexed single-cell approaches including single-cell RNA sequencing (scRNAseq) have emerged as resources to help answer these questions. In this review, we query recently published scRNAseq datasets to support companion macrophage imaging, with particular focus on using dextran-based nanoparticles to predict the action of anti-cancer nanotherapies and monoclonal antibodies.

There have been many efforts to grow high-quality, single-crystalline graphene on a cheap substrate, such as a metal foil. However, control of nucleation and growth of individual flakes, as well as their seamless stitching, remains elusive. Here we demonstrate a new strategy to fast and facile synthesis of large scale single-crystal graphene on copper foil. Polycrystalline Cu foils were first converted to single-crystal Cu foils through high-temperature annealing processes. Then, a sodium chloride (NaCl) additive was introduced during chemical vapor deposition growth of graphene on the Cu foils. Investigation of early stage growth in this process suggests that the NaCl additive enhances nucleation events and depresses dendritic growth, producing high-density graphene flakes (GFs) with crystallographically well-defined edges: (i) rectangular-shaped GFs on Cu(100) and (ii) hexagonal-shaped GFs on Cu(111). Density functional theory calculations show that NaCl can assist in the elimination of remnant oxygen atoms on the Cu surface and promote epitaxial interactions between Cu and graphene. This behavior was further exploited to achieve large-scale single-crystal graphene through epitaxial, seamless stitching of hexagonal GFs within 90 s.

Sessile plants have evolved distinct mechanisms to respond and adapt to adverse environmental conditions through diverse mechanisms including RNA processing. While the role of RNA processing in the stress response is well understood for Arabidopsis thaliana, limited information is available for rice (Oryza sativa). Here, we show that OsFKBP20-1b, belonging to the immunophilin family, interacts with the splicing factor OsSR45 in both nuclear speckles and cytoplasmic foci, and plays an essential role in post-transcriptional regulation of abiotic stress response. The expression of OsFKBP20-1b was highly upregulated under various abiotic stresses. Moreover genetic analysis revealed that OsFKBP20-1b positively affected transcription and pre-mRNA splicing of stress-responsive genes under abiotic stress conditions. In osfkbp20-1b loss-of-function mutants, the expression of stress-responsive genes was downregulated, while that of their splicing variants was increased. Conversely, in plants overexpressing OsFKBP20-1b, the expression of the same stress-responsive genes was strikingly upregulated under abiotic stress. In vivo experiments demonstrated that OsFKBP20-1b directly maintains protein stability of OsSR45 splicing factor. Furthermore, we found that the plant-specific OsFKBP20-1b gene has uniquely evolved as a paralogue only in some Poaceae species. Together, our findings suggest that OsFKBP20-1b-mediated RNA processing contributes to stress adaptation in rice.

Exploring bifunctional electrocatalysts to lower the activation energy barriers for sluggish electrochemical reactions for both the oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) are of great importance in achieving lower energy consumption and higher conversion efficiency for future energy conversion and storage system. Despite the excellent performance of precious metal-based electrocatalysts for OER and ORR, their high cost and scarcity hamper their large-scale industrial application. As alternatives to precious metal-based electrocatalysts, the development of earth-abundant and efficient catalysts with excellent electrocatalytic performance in both the OER and the ORR is urgently required. Herein, we report a core-shell CoFeS

The synthesis of colloidal III-V quantum dots (QDs), particularly of the arsenides and antimonides, has been limited by the lack of stable and available group V precursors. In this work, we exploit accessible InCl

The aging of ZnO nanoparticles in quantum dot light-emitting diode (QD-LED) structures was studied. Coarsening of as-synthesized ZnO nanoparticles is observed in both solution and thin film structures, which potentially deteriorates the performance of QD-LED devices over time. First, the temperature effect on ZnO coarsening was investigated, and it was revealed that aging of ZnO nanoparticles is faster at higher temperature due to a diffusion-controlled mechanism of nanoparticle coarsening. To observe aggregation of ZnO in the film state, the electron transporting part (ZnO/Al) of the QD-LED structure was prepared. The current density of a ZnO film and an electron-only device (QD/ZnO between two electrodes) was also measured. Resistance of the film increased as a function of aging time, which corresponded with observations of the ZnO film by optical microscopy. Aggregation of ZnO nanoparticles was directly measured by the root-mean-square value using atomic force microscopy. Ethanolamine (EA) stabilizer was added to the ZnO solution to disperse the ZnO nanoparticles without aggregation. The effect of EA on the surface passivation of the ZnO found to suppress pinhole formation, as revealed by scanning electron microscopy observations. Finally, the device lifetime was measured for QD-LEDs with EA-stabilized ZnO to understand the effect of ZnO aging on long-term QD-LED device operation.

Colloidal nanorod heterostructures of I–III–VI2 semiconductors have been synthesized in a solution starting from wurtzite-like CuGaS2 nanorods. Growth of CuInS2 or CuInSe2 on CuGaS2 nanorods result...

Totally colorless, transparent, and highly refractive poly(phenylene thioether ether)s (PPTEs) containing thianthrene-2,7-disulfanyl moiety were developed in this study. A new 4,4′-diol aromatic compound, 2,7-(4,4′-diphenol)thiothianthrene (DPTT), with a high sulfur content was designed and synthesized to develop polymers with high refractive indices and high thermal stabilities. The PPTEs were prepared by polycondensation of DPTT with organic dihalogen compounds, such as 2,6-difluorobenzonitrile (DFBN) and 4,6-dichloro-2-(methylthio)pyrimidine (DCMP). The obtained polymers showed good thermal stabilities such as relatively high glass transition temperatures (Tgs) in the range of 153–176 °C and 5% weight loss temperatures (T5%) over 344 °C. The cut-off wavelengths (λ0) of the PPTE films are shorter than 343 nm, and they have a transmittance higher than 93% at 550 nm. The combination of the pyrimidine and high sulfur-containing thianthrene derivatives provides the PPTEs with a high refractive index of 1.7204 and a small birefringence of 0.0106 at 637 nm.

Strongly coupled, epitaxially fused colloidal nanocrystal (NC) solids are promising solution-processable semiconductors to realize optoelectronic devices with high carrier mobilities. Here, we demonstrate sequential, solid-state cation exchange reactions to transform epitaxially connected PbSe NC thin films into Cu2Se nanostructured thin-film intermediates and then successfully to achieve zinc-blende, CdSe NC solids with wide epitaxial necking along {100} facets. Transient photoconductivity measurements probe carrier transport at nanometer length scales and show a photoconductance of 0.28(1) cm2 V-1 s-1, the highest among CdSe NC solids reported. Atomic-layer deposition of a thin Al2O3 layer infiltrates and protects the structure from fusing into a polycrystalline thin film during annealing and further improves the photoconductance to 1.71(5) cm2 V-1 s-1 and the diffusion length to 760 nm. We fabricate field-effect transistors to study carrier transport at micron length scales and realize high electron mobilities of 35(3) cm2 V-1 s-1 with on-off ratios of 106 after doping.

The analysis of circulating tumor cells (CTCs) in the peripheral blood of cancer patients is critical in clinical research for further investigation of tumor progression and metastasis. In this study, we present a novel surface-enhanced Raman scattering (SERS) substrate for the efficient capture and characterization of cancer cells using silver nanoparticles-reduced graphene oxide (AgNPs-rGO) composites. A pulsed laser reduction of silver nanowire-graphene oxide (AgNW-GO) mixture films induces hot-spot formations among AgNPs and artificial biointerfaces consisting of rGOs. We also use in situ electric field-assisted fabrication methods to enhance the roughness of the SERS substrate. The AgNW-GO mixture films, well suited for the proposed process due to its inherent electrophoretic motion, is adjusted between indium tin oxide (ITO) transparent electrodes and the nano-undulated surface is generated by applying direct-current (DC) electric fields during the laser process. As a result, MCF7 breast cancer cells are efficiently captured on the AgNPs-rGO substrates, about four times higher than the AgNWs-GO films, and the captured living cells are successfully analyzed by SERS spectroscopy. Our newly designed bifunctional substrate can be applied as an effective system for the capture and characterization of CTCs.

Summary Whole‐genome annotation error that omits essential protein‐coding genes hinders further research.We developed Target Gene Family Finder (tgfam‐finder), an alternative tool for the structural annotation of protein‐coding genes containing target domain(s) of interest in plant genomes. tgfam‐finder took considerably reduced annotation run‐time and improved accuracy compared to conventional annotation tools.Large‐scale re‐annotation of 50 plant genomes identified an average of 150, 166 and 86 additional far‐red‐impaired response 1, nucleotide‐binding and leucine‐rich‐repeat, and cytochrome P450 genes, respectively, that were missed in previous annotations. We detected significantly higher number of translated genes in the new annotations using mass spectrometry data from seven plant species compared to previous annotations. tgfam‐finder along with the new gene models can provide an optimized platform for comprehensive functional, comparative, and evolutionary studies in plants.

Li-iodine chemistry is of interest for electrochemical energy storage because it has been shown to provide both high power and high energy density. However, Li-iodine batteries are typically formed using Li metal and elemental iodine, which presents safety and fabrication challenges (e.g., the high vapor pressure of iodine). These disadvantages could be circumvented by using LiI as a starting cathode. Here, we present fabrication of a reduced graphene oxide (rGO)/LiI composite cathode, enabling for the first time the use of LiI as the Li-ion battery cathode. LiI was coated on rGO by infiltration of an ethanolic solution of LiI into a compressed rGO aerogel followed by drying. The free-standing rGO/LiI electrodes show stable long-term cycling and good rate performance with high specific capacity (200 mAh g–1 at 0.5 C after 100 cycles) and small hysteresis (0.056 V at 1 C). Shuttling was suppressed significantly. We speculate the improved electrochemical performance is due to strong interactions between the...

While adipose-derived stem cell-conditioned medium (ADSC-CM) has been demonstrated to promote skin wound healing, the mechanism regulating this effect remains unelucidated. In this study, we aimed to investigate the role of Ell3 in the wound healing activity of ADSC-CM. In vitro analysis revealed that Ell3 suppression in ADSCs impairs the promotive activity of ADSC-CM on the proliferation and migration of mouse embryonic fibroblasts (MEF) and normal human dermal fibroblasts (NHDF). Consistently, the expression of MMP family genes, which regulate cell proliferation and migration, was significantly suppressed in MEF and NHDF treated with siEll3-transfected ADSC-CM. Proinflammatory cytokines, such as interleukin-1 and interleukin-6, were highly expressed in MEF treated with siEll3-transfected ADSC-CM. The wound healing activity of siEll3-transfected ADSC-CM was significantly lower than that of the control in vivo. Our results suggest that Ell3 may contribute to the inhibition of inflammatory response during skin wound healing.

Anisotropic semiconductor nanoparticles find use in various applications ranging from electronics to photocatalysis and biolabeling. Batch synthesis methods typically used for their synthesis are often hampered by slow mixing, slow heating / cooling, and lack of batch-to-batch reproducibility, especially when scaling up. The modular continuous flow reactor reported here overcomes some of these challenges. It enables air-sensitive syntheses at temperatures as high as 400 °C, supports rapid heating and cooling times (~1 s or less), and enables syntheses that involve reagents that are viscous or even solid at room temperature. For validation we pursued two systems: the synthesis of (i) CdSe nanorods and bipods, and of (ii) ZnSe nanorods. Nanoparticles with low variance in quantum confined dimension (width) - 16% for CdSe and 11% for ZnSe - were obtained. For comparison, the same products were also synthesized using two batch approaches, hot-injection and heat-up, under similar conditions. The batch products were less uniform: 30% variance in quantum confined dimension. Furthermore, the lack of precise temperature control in the batch processes resulted in CdSe nanorods with irregular shaped, jagged branches whereas the continuous process produced CdSe nanorods with uniform, straight branches. The modular continuous flow reactor design is suited for scale up, allowing working flow rates as high as ~10 mL/min, which translates into a production rate of ~158 g / day for CdSe.

Colloidal quantum dots (QDs) are emerging as solution-processable, high-performance materials for light-emitting diodes (LEDs). Understanding the failure mechanism(s) is of both fundamental and practical importance, yet little is known of how QD-LEDs fail. Here, we have carried out accelerated device lifetime measurements on double heterojunction nanorod- (DHNR) and QD-LEDs. A common dependence of device lifetime on the initial driving voltage is observed over more than two orders of magnitude range in the initial luminance. This behavior is independent of whether the emitting materials are DHNRs or QDs prepared under different conditions. Reducing the hole injection barrier by doping HTL allows lower voltage operation, leading to longer device lifetimes. DHNRs with a band structure that further lowers the hole injection barrier require even lower driving voltages and therefore lead to longer device lifetimes than core/shell QDs. At 1000 cd m−2, the DHNR-LED exhibits no significant degradation even after more than 200 h of continuous operation. QD-LEDs, on the other hand, are completely degraded in less than ∼100 h under the same initial luminance conditions. Hole accumulation/trapping leading to HTL degradation, which in turn deteriorates electroluminescence but not the photoluminescence, is suggested to be the main cause of degradation of both DHNR- and QD-LEDs.

ZEB1 has intrinsic oncogenic functions that control the epithelial-to-mesenchymal transition (EMT) of cancer cells, impacting tumorigenesis from its earliest stages. By integrating microenvironment signals and being implicated in feedback regulatory loops, ZEB1 appears to be a central switch that determines EMT and metastasis of cancer cells. Here, we found that ZEB1 collaborates with ELK3, a ternary complex factor belonging to the ETS family, to repress E-cadherin expression. ZEB1 functions as a transcriptional activator of ELK3. We first identified that ELK3 and ZEB1 have a positively correlated expression in breast cancer cells by using multiple databases for correlation analysis. Molecular analysis revealed that ZEB1 functions as a transcriptional activator of ELK3 expression. GST pull-down assay and coimmunoprecipitation analysis of wild-type or domain deletion mutants of ZEB1 and ELK3 showed that these 2 proteins directly bound each other. Furthermore, we demonstrated that ZEB1 and ELK3 collaborate to repress the expression of E-cadherin, a representative protein that initiates EMT. Our finding suggested that ELK3 is a novel factor of the ZEB1/E-cadherin axis in triple-negative breast cancer cells. Implications: ELK3 is a novel factor in the ZEB1/E-cadherin axis and ZEB1 has a dual role in ELK3 as a transcriptional activator and as a collaborator to repress E-cadherin expression in triple-negative breast cancer cells.

Colloidal semiconductor nanocrystals (NCs) are a promising materials class for solution-processable, next-generation electronic devices. However, most high-performance devices and circuits have bee...

Tumor-associated lymphatic vessels (LV) serve as a route of cancer dissemination through the prometastatic crosstalk between lymphatic endothelial cells (LECs) lining the LVs and cancer cells. Compared to blood endothelial cell-derived angiocrine factors, however, LEC-secreted factors in the tumor microenvironment and their roles in tumor metastasis are poorly understood. Here, we report that ELK3 expressed in LECs contributes to the dissemination of cancer cells during tumor growth by providing oncogenic miRNAs to tumor cells through exosomes. We found that conditioned medium from ELK3-suppressed LECs (LCM) lost its ability to promote the migration and invasion of breast cancer cells such as MDA-MB-231, Hs578T and BT20 in vitro. Suppression of ELK3 in LECs diminished the ability of LECs to promote tumor growth and metastasis of MDA-MB-231 in vivo. Exosomes derived from LECs significantly increased the migration and invasion of MDA-MB-231 in vitro, but ELK3 suppression significantly diminished the pro-oncogenic activity of exosomes from LECs. Based on the miRNA expression profiles of LECs and functional analysis, we identified miR-503-3p, miR-4269 and miR-30e-3p as downstream targets of ELK3 in LECs, which cause the above phenotype of cancer cells. These findings strongly suggest that ELK3 expressed in LECs is a major regulator that controls the communication between the tumor microenvironment and tumors to support cancer metastasis.

Colloidal semiconductor nanocrystals (NCs) are a promising materials class for solution-processable, next-generation electronic devices. However, most high-performance devices and circuits have been achieved using NCs containing toxic elements, which may limit their further device development. We fabricate high mobility CuInSe

Colloidal quantum dots (QDs) have widely been considered as emerging candidates for solution-processable optoelectronic devices. Especially, QDs that are optically active in NIR and SWIR spectral windows, offer a great promise for infrared emitters, infrared photodetectors, photovoltaics, and biological imaging applications. It is thus essential to develop high-quality infrared QDs without the use of heavy metals such as cadmium, lead, or mercury. Among various semiconducting materials, III-V compound semiconductors show great potential in practical optoelectronic applications not only due to their wide tunability in the infrared region, but also due to their excellent optical and electronic properties. However, the synthesis of III-V semiconductor-based QDs has been limited by the lack of understanding about the precursors of group V elements such as P, As and Sb. In this presentation, we would like to discuss about the pnictogen precursors to synthesize various III-V QDs and also the surface properties of the resultant QDs. By controlling the reaction process with the pnictogen precursors, we achieve size and stoichiometry-tunable III-V QDs including InP, InAs, InSb and alloy QDs. Based on structural, analytical, optical, and electrical characterization of the QDs, we study the effects of surface treatments on their optoelectronic properties. We demonstrate that III-V QD thin films are promising candidate materials for infrared optoelectronic devices. Figure 1

The reliability of negative temperature coefficient (NTC) thermistors is one of the important factors for the excellent performance of the battery management system in electric vehicles. The electrical properties of the thermistor can be explained by the indirect electron jump between Mn3+ and Mn4+ at the B-sites in a spinel-type thermistor. Additionally, different types of dopants, such as Fe, Cu, Zn, Cr, and Mn, are considered as electrical modifiers that can further improve the electrical properties of the thermistor. For example, Cu is often added to NTC thermistors, occupying the octahedral sites in a spinel-type thermistor, which can play an important role in conduction with the Mn cations. Addition of Fe is also widely used in NTC thermistors owing to its high sensitivity, B constant, and stability. In this study, composition-dependent structural and electrical properties of Cu0.2/Fey-co-doped Ni0.3Mna-x-yCo0.9O4 (NMC) are investigated. Cu/Fe-co-doped NMC shows the R25 and B25/85 constant values of 4490–12730 Ω and 3185–3490 K, respectively, exhibiting a typical ρ–T curve of NTC thermistors. Higher B constant and reliable electrical stability are observed for Cu/Fe-co-doped NMC. Based on the relationship between the cationic oxidation states and electrical properties of Cu/Fe-co-doped NMC, the hopping conduction mechanism is discussed.

Crystal structures and hopping motions of cobalt manganese spinel oxides across a wide composition range (CoxMn3−xO4 (CMO), 0.9 ≤ x ≤ 2.7) are investigated in order to clarify the corresponding mechanisms of electrical behaviors as negative temperature coefficient thermistors. Based on the diffraction measurements, a tetragonal to cubic spinel transition are observed mostly with increasing Co content. Hopping distance for a series of CMO are calculated by the variable range hopping mechanism, which is changed as a function of composition, resulting to the observed unique electrical properties. According to the electrical and structural analysis, the electrical properties of CMO compounds with different Co contents majorly determined by tetragonal to cubic phase transition, cation distribution, and hopping distance. In addition, the formation of secondary phase (i.e., CoO) and another CMO phase may also significantly affect the electrical properties.