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The Hippo pathway is an important pathway to control cell proliferation and organ size. By sensing extracellular matrix stiffness and intercellular mechanical force and converting them into molecular signal transduction, through a series of cascade amplification effects of kinases, the final the phosphorylation of YAP/TAZ, the main downstream target of the Hippo pathway, plays a series of regulatory roles. Although many studies have shown that Hippo signaling changes during skeletal muscle hypertrophy, the complex mechanism of Hippo signaling in skeletal muscle hypertrophy remains to be further studied. In this review, we summarize the relationship between Hippo-YAP/TAZ signaling and skeletal muscle hypertrophy and sort out the contribution of the main factors in the process of skeletal muscle hypertrophy.

The role of Pygo1 in mammalian cardiac disease remains unelucidated. In this study, we found that Pygo1 is associated with human pathological hypertrophy. Cardiac-specific overexpression of Pygo1 in mice spontaneously led to cardiac hypertrophy, accompanied by declined cardiac function, increased heart weight/body weight and heart weight/tibial length ratios, and increased cell size. Meanwhile, cardiac function was improved when expression of Pygo1 interfered in hypertrophy-model mice. Our study is the first to present in vivo evidence demonstrating that Pygo1 regulates pathological cardiac hypertrophy in a canonical Wnt/β-catenin-dependent manner, which may provide new clues for a tissue-specific clinical treatment targeting this pathway.

Background: Previously, we first identified the human tripartite motifcontaining protein 45 (TRIM45) acts as a novel transcriptional repressor in mitogenactivated protein kinase (MAPK) signaling pathway. After that, the inhibitory role of TRIM45 in the development of tumor was gradually unveiled. However, the function of TRIM45 in the tumorigenesis of lung cancer has not been characterized. Methods and Results: In this study, we found that TRIM45 was up-regulated in earlystage human non-small-cell lung cancer (NSCLC) tissues. Overexpression of TRIM45 in lung cancer cells induces G1 arrest and promotes apoptosis, which accompanied by upregulated expression of RB, p16, p53, p27Kip1, and Caspase3 and down-regulated expression of CyclinE1 and CyclinE2. Further detection of the expression of the molecules in the MAPK signaling pathway revealed that overexpression of TRIM45 in lung cancer cells promotes phosphorylated p38 (p-p38) activation and inhibits phosphorylated ERK (p-ERK) activation. In accordance with this, p-p38 is increased while p-ERK is decreased in lung cancer tissues. Conclusion: These findings indicate that TRIM45 plays an inhibitory role in the tumorigenesis of lung cancer. High-level expression of TRIM45 in lung cancer tissue may promote cell apoptosis by activating p38 signal and inhibit proliferation by down-regulating p-ERK, which provides a new clue for understanding the tumorigenesis of lung cancer.

Due to importantly beneficial effects on physical and mental health and strong association with many rehabilitation programs, Physical Activity Recognition and Measure (PARM) has been widely recognised as a key paradigm for a variety of smart healthcare applications. Traditional methods for PARM relies on designing and utilising Data fusion or machine learning techniques in processing ambient and wearable sensing data for classifying types of physical activity and removing their uncertainties. Yet they mostly focus on controlled environments with the aim of increasing types of identifiable activity subjects, improved recognition accuracy and measure robustness. The emergence of the Internet of Things (IoT) enabling technology is transferring PARM studies to an open and dynamic uncontrolled ecosystem by connecting heterogeneous cost-effective wearable devices and mobile apps and various groups of users [35] . Little is currently known about whether traditional Data fusion techniques can tackle new challenges of IoT environments and how to effectively harness and improve these technologies. In an effort to understand potential use and opportunities of Data fusion techniques in IoT enabled PARM applications, this paper will give a systematic review, critically examining PARM studies from a perspective of a novel 3D dynamic IoT based physical activity collection and validation model. It summarized traditional state-of-the-art data fusion techniques from three plane domains in the 3D dynamic IoT model: devices, persons and timeline. The paper goes on to identify some new research trends and challenges of data fusion techniques in the IoT enabled PARM studies, and discusses some key enabling techniques for tackling them.

Simple Summary Excessive exercise can lead to muscle atrophy, which is particularly concerning in professional athletes. However, the effects of excessive exercise on the skeletal muscle system remain unclear. Here, we used a zebrafish model of excessive exercise to identify genes that are dysregulated during excessive exercise. We mapped the identified genes to regulatory networks to gain an understanding of their functions during muscle atrophy. We identified several important mechanisms by which excessive exercise can lead to muscle wasting and prevent regeneration. Our findings provide fundamental knowledge on the effect of overtraining on the skeletal muscle system, and will enable better monitoring of muscle condition in athletes. Abstract Long-term imbalance between fatigue and recovery may eventually lead to muscle weakness or even atrophy. We previously reported that excessive exercise induces pathological cardiac hypertrophy. However, the effect of excessive exercise on the skeletal muscles remains unclear. In the present study, we successfully established an excessive-exercise-induced skeletal muscle atrophy zebrafish model, with decreased muscle fiber size, critical swimming speed, and maximal oxygen consumption. High-throughput RNA-seq analysis identified differentially expressed genes in the model system compared with control zebrafish. Gene ontology and KEGG enrichment analysis revealed that the upregulated genes were enriched in autophagy, homeostasis, circadian rhythm, response to oxidative stress, apoptosis, the p53 signaling pathway, and the FoxO signaling pathway. Protein–protein interaction network analysis identified several hub genes, including keap1b, per3, ulk1b, socs2, esrp1, bcl2l1, hsp70, igf2r, mdm2, rab18a, col1a1a, fn1a, ppih, tpx2, uba5, nhlrc2, mcm4, tac1, b3gat3, and ddost, that correlate with the pathogenesis of skeletal muscle atrophy induced by excessive exercise. The underlying regulatory pathways and muscle-pressure-response-related genes identified in the present study will provide valuable insights for prescribing safe and accurate exercise programs for athletes and the supervision and clinical treatment of muscle atrophy induced by excessive exercise.

Herein, we aimed to establish an aerobic exercise-induced physiological myocardial hypertrophy zebrafish (Danio rerio) model and to explore the underlying molecular mechanism. After 4 weeks of aerobic exercise, the AMR and Ucrit of the zebrafish increased and the hearts were enlarged, with thickened myocardium, an increased number of myofilament attachment points in the Z-line, and increased compaction of mitochondrial cristae. We also found that the mTOR signaling pathway, angiogenesis, mitochondrial fusion, and fission event, and mitochondrial autophagy were associated with the adaptive changes in the heart during training. In addition, the increased mRNA expression of genes related to fatty acid oxidation and antioxidation suggested that the switch of energy metabolism and the maintenance of mitochondrial homeostasis induced cardiac physiological changes. Therefore, the zebrafish heart physiological hypertrophy model constructed in this study can be helpful in investigating the cardioprotective mechanisms in response to aerobic exercise.

Driven by the new revolution in healthcare, the importance of understanding Physical Activity (PA) in the uncertain, dynamic, free-living environments has been drawing growing attention. However, there is a lack of holistic investigation on how to improve the accuracy of PA recognition in free-living environments using cost-effective wearable devices with feasible algorithms. In this paper, we design a two-layer hybrid hierarchical model for accessing and evaluating cost-effective wearable intelligence approaches for PA recognition in free-living environments. The hypothesis of this model first suggests utilising less-attached on-body consumable wearables like belt and wristband devices, and then building up a PA dataset collected in free-living environments like an elderly home, hospital, office and gym. The model is then defined with components of lightGBM (LGB) and Artificial Neural Networks (ANN) for coarse and fine-grained classification, parameters of achieving high recognition rate including time window sizes, features and activation functions. The experimental results indicate that our model has superior ability over other state-of-the-art algorithms in classifying three typical types of PA (dynamic, sedentary, and transitional) with an average accuracy up to 84%. Specifically, our model performs good results of PA recognition with the ageing populations including 5 Mild Cognitive Impairment (MCI) and 17 Parkinson's disease (PD) patients.

Exercise-induced cardiac remodeling has aroused public concern for some time, as sudden cardiac death is known to occur in athletes; however, little is known about the underlying mechanism of exercise-induced cardiac injury. In the present study, we established an excessive exercise-induced pathologic cardiac hypertrophy model in zebrafish with increased myocardial fibrosis, myofibril disassembly, mitochondrial degradation, upregulated expression of the pathological hypertrophy marker genes in the heart, contractile impairment, and cardiopulmonary function impairment. High-throughput RNA-seq analysis revealed that the differentially expressed genes were enriched in the regulation of autophagy, protein folding, and degradation, myofibril development, angiogenesis, metabolic reprogramming, and insulin and FoxO signaling pathways. FOXO proteins may be the core mediator of the regulatory network needed to promote the pathological response. Further, PPI network analysis showed that pik3c3, gapdh, fbox32, fzr1, ubox5, lmo7a, kctd7, fbxo9, lonrf1l, fbxl4, nhpb2l1b, nhp2, fbl, hsp90aa1.1, snrpd3l, dhx15, mrto4, ruvbl1, hspa8b, and faub are the hub genes that correlate with the pathogenesis of pathological cardiac hypertrophy. The underlying regulatory pathways and cardiac pressure-responsive molecules identified in the present study will provide valuable insights for the supervision and clinical treatment of pathological cardiac hypertrophy induced by excessive exercise.

Physical activity (PA) is widely recognized as one of the important elements of personal healthy life. To date, as the development of wearable sensing technologies, it is possible to utilize wearable devices and machine learning algorithms to efficiently and accurately monitor PA types, intensity and its associated human pattern for many health applications. But there is a trade-off between less-attachment of wearable devices and achievement of high accuracy in existing PA recognition studies. This paper attempts to investigate possible utilisation of Artificial Neural Networks (ANN) achieving high recognition accuracy of PA using less-attachments of wearable devices. Following a four-steps designed experimental protocol, we collect the real activities dataset with only belt and wristband devices from 10 healthy subjects at home and gym environment. The parameters of typical PA recognition with ANN including time window sizes, features and activation functions are evaluated under 24 different subjects of activities. The experimental results indicate that ANN dealing with belt and wristband data can achieve satisfactory PA recognition results in dynamic and sedentary activities but suffers from transitional activities in both environments.

The assembly of LIM-homeodomain (LIM-HD) transcriptional complex plays important roles in early neuronal development. The stability of LIM-HD is controlled by single-strand binding protein 3 (SSBP3) via a cascade mechanism protecting it from proteasomal degradation. The expression level of SSBP3 has to be precisely regulated. Although a decrease of SSBP3 level is associated with several diseases, the mechanism of SSBP3 downregulation and whether SSBP3 itself is subject to proteasomal degradation remain largely unknown. Two strongly conserved transcripts of the SSBP3 gene, SSBP3a and SSBP3c, were cloned from a human brain cDNA library. By RT-PCR, we show that Ssbp3c is continuously expressed in both embryonic and adult mouse brain, whereas Ssbp3a is restricted to embryonic brain tissue. By co-IP and GST pulldown assays, we identified SIVA1 as a novel SSBP3-binding factor. In a ubiquitination assay, we show that SIVA1 enhances the ubiquitination of SSBP3 and regulates its abundance. Our findings reveal the proteasomal degradation of SSBP3 for the first time and provide a rationale for an SIVA1-SSBP3-dependent mechanism for the disassembly of LIM-HD multiprotein complexes.

15-hydroxyprostaglandin dehydrogenase (15-PGDH; encoded by HPGD) is ubiquitously expressed in mammalian tissues and catalyzes the degradation of prostaglandins (PGs; mainly PGE2, PGD2, and PGF2α) in a process mediated by solute carrier organic anion transport protein family member 2A1 (SLCO2A1; also known as PGT, OATP2A1, PHOAR2, or SLC21A2). As a key enzyme, 15-PGDH catalyzes the rapid oxidation of 15-hydroxy-PGs into 15-keto-PGs with lower biological activity. Increasing evidence suggests that 15-PGDH plays a key role in many physiological and pathological processes in mammals and is considered a potential pharmacological target for preventing organ damage, promoting bone marrow graft recovery, and enhancing tissue regeneration. Additionally, results of whole-exome analyses suggest that recessive inheritance of an HPGD mutation is associated with idiopathic hypertrophic osteoarthropathy. Interestingly, as a tumor suppressor, 15-PGDH inhibits proliferation and induces the differentiation of cancer cells (including those associated with colorectal, lung, and breast cancers). Furthermore, a recent study identified 15-PGDH as a marker of aging tissue and a potential novel therapeutic target for resisting the complex pathology of aging-associated diseases. Here, we review and summarise recent information on the molecular functions of 15-PGDH and discuss its pathophysiological implications.

Non-alcoholic fatty liver disease (NAFLD) is a common disease that causes serious liver damage. Exercise is recognized as a non-pharmacological tool to improve the pathology of NAFLD. However, the antioxidative effects and mechanisms by which exercise ameliorates NAFLD remain unclear. The present study conducted exercise training on zebrafish during a 12-week high-fat feeding period to study the antioxidant effect of exercise on the liver. We found that swimming exercise decreased lipid accumulation and improved pathological changes in the liver of high-fat diet-fed zebrafish. Moreover, swimming alleviated NOX4-derived reactive oxygen species (ROS) overproduction and reduced methanedicarboxylic aldehyde (MDA) levels. We also examined the anti-apoptotic effects of swimming and found that it increased the expression of antiapoptotic factor bcl2 and decreased the expression of genes associated with apoptosis (caspase3, bax). Mechanistically, swimming intervention activated SIRT1/AMPK signaling-mediated lipid metabolism and inflammation as well as enhanced AKT and NRF2 activation and upregulated downstream antioxidant genes. In summary, exercise attenuates pathological changes in the liver induced by high-fat diets. The underlying mechanisms might be related to NRF2 and mediated by SIRT1/AMPK signaling.

GC-1 and GC-2 are two globular clusters (GCs) in the remote halo of M81 and M82 in the M81 group discovered by Jang et al. using the {\it Hubble Space Telescope} ({\it HST}) images. These two GCs were observed as part of the Beijing--Arizona--Taiwan--Connecticut (BATC) Multicolor Sky Survey, using 14 intermediate-band filters covering a wavelength range of 4000--10000 \AA. We accurately determine these two clusters' ages and masses by comparing their spectral energy distributions (from 2267 to 20000~{\AA}, comprising photometric data in the near-ultraviolet of the {\it Galaxy Evolution Explorer}, 14 BATC intermediate-band, and Two Micron All Sky Survey near-infrared $JHK_{\rm s}$ filters) with theoretical stellar population-synthesis models, resulting in ages of $15.50\pm3.20$ for GC-1 and $15.10\pm2.70$ Gyr for GC-2. The masses of GC-1 and GC-2 obtained here are $1.77-2.04\times 10^6$ and $5.20-7.11\times 10^6 \rm~M_\odot$, respectively. In addition, the deep observations with the Advanced Camera for Surveys and Wide Field Camera 3 on the {\it HST} are used to provide the surface brightness profiles of GC-1 and GC-2. The structural and dynamical parameters are derived from fitting the profiles to three different models; in particular, the internal velocity dispersions of GC-1 and GC-2 are derived, which can be compared with ones obtained based on spectral observations in the future. For the first time, in this paper, the $r_h$ versus $M_V$ diagram shows that GC-2 is an ultra-compact dwarf in the M81 group., Comment: MNRAS 468, 4513-4528 (2017), 16 pages, 9 figures and 11 tables

Myocardial infarction is due to lasting and serious myocardial ischemic that leads to myocardial necrosis and cardiac remodeling, and can consequently results in heart failure. Traditional treatment for myocardial infarction includes drug therapy, thrombolytic therapy, percutaneous coronary intervention (PCI), and coronary artery bypass graft (CABG) surgery. Although these treatments can to some extent relieve the symptom of myocardial ischemia, they fail to repair the necrotic heart tissues. Myocardial regeneration is undoubtedly the best solution to the clinical problems of myocardial infarction treatment. The review briefly illustrated the pros and cons of the traditional treatments of myocardial infarction, and focused on the application of new strategies for myocardial infarction treatment using myocardial regeneration.

Magnetoreception is essential for magnetic orientation in animal migration. The molecular basis for magnetoreception has recently been elucidated in fruitfly as complexes between the magnetic receptor magnetoreceptor (MagR) and its ligand cryptochrome (Cry). MagR and Cry are present in the animal kingdom. However, it is unknown whether they perform a conserved role in diverse animals. Here we report the identification and expression of zebrafish MagR and Cry homologs towards understanding their roles in lower vertebrates. A single magr gene and 7 cry genes are present in the zebrafish genome. Zebrafish has four cry1 genes (cry1aa, cry1ab, cry1ba and cry1bb) homologous to human CRY1 and a single ortholog of human CRY2 as well as 2 cry-like genes (cry4 and cry5). By RT-PCR, magr exhibited a high level of ubiquitous RNA expression in embryos and adult organs, whereas cry genes displayed differential embryonic and adult expression. Importantly, magr depletion did not produce apparent abnormalities in organogenesis. Taken together, magr and cry2 exist as a single copy gene, whereas cry1 exists as multiple gene duplicates in zebrafish. Our result suggests that magr may play a dispensable role in organogenesis and predicts a possibility to generate magr mutants for analyzing its role in zebrafish.

Background CXXC-type zinc-finger protein CXXC5 has been reported to be associated with the development of cardiovascular disease. Recently, through signaling pathway screening we found that CXXC5 activated Tgfβ and myocardial differentiation signaling pathways simultaneously. Although the physiological and pathological function of CXXC5 in many organs has been well elucidated, its function in heart remains unclear. Methods and results Here, we found that zebrafish CXXC5 and SMAD were interacting through ZF-CXXC and MH1 domain. Over-expression of CXXC5 in cardiomyocyte increased the luciferase report activity of Tgfβ signaling pathway. Spatiotemporal expression profile of cxxc5 showed that it consistently expressed during cardiogenesis. Knockdown of cxxc5 in zebrafish displayed looping defects, cardiac dysplasia, pericardial edema, and decreased contraction ability, accompanied with down-regulation of members referring to cardiac looping downstream genes of Tgfβ signaling pathway, such as nkx2.5 , hand2 , and has2 . Co-injection of hand2 mRNA with cxxc5 morpholino rescued the cardiac looping detects. Conclusion Our study is the first to provide an in vivo evidence for cxxc5 regulating heart development and cardiac looping via Tgfβ related signaling pathway. This finding suggested that CXXC5 may serve as a possible marker that has potential diagnostic and prognostic value in fetus with congenital heart disease.

CXXC5 is a member of the CXXC-type zinc-finger domain containing protein family, which is suggested to function in gene transcription, cell adhesion and cytoskeleton organization. Previous studies have revealed that CXXC5 is expressed in skeletal muscle, but whether it regulates skeletal myogenesis is yet unknown. Here, we screened for the possible signaling pathways in which CXXC5 might participate using luciferase gene reporters. The results indicated that CXXC5 significantly increased the activities of the promoters of genes involved in skeletal muscle differentiation. We therefore studied the role of CXXC5 during skeletal myogenesis in C2C12 myoblasts. Our findings suggest that overexpression of CXXC5 in C2C12 myoblasts facilitated myocyte differentiation, while RNAi interference of CXXC5 significantly inhibited the differentiation of C2C12 myoblasts. This study suggests that CXXC5 plays a significant role in regulating skeletal myogenesis.

Using the promoter for cardiac myosin light chain 2 (cmlc2) gene, an expression vector pTol2-cmlc2-IRES- EGFP for making heart-specific expression of exogenous gene in transgenic zebrafish was generated previously. Here, we reported the construction of a transgenic zebrafish line which stably expresses EGFP using this vector, and the effects of EGFP on the heart development and cardiac function of this transgenic zebrafish line were preliminarily analyzed. The results showed that the green fluorescence signal of cmlc2:EGFP line under fluorescence microscopy specifically expressed in heart and faithfully recapitulated both the spatial and temporal expression patterns of endogenous cmlc2 gene revealed by in situ hybridization in the early developmental stages. The cardiac morphology and development of this transgenic zebrafish line remained to be normal. Furthermore, the heart morphology and physiological function of this transgenic line have been analyzed using M-mode analysis. The results showed that there was no significant difference between the cmlc2:EGFP and the wild type lines with respect to heart period, heart rate, diastolic surface area and systolic surface area, and fractional area change. No tachyarrhythmia was observed in the embryos from either line. Thus, the excessive expression of EGFP in this transgenic line seemed to exert no detrimental effects on the function and development of zebrafish hearts during early stages. Our study laid a foundation for the construction of exogenous gene transgenic line using pTol2-cmlc2-IRES-EGFP vector to study the function of genes that expressed in heart.

The human Hole gene (hHole) encodes a six-transmembrane protein with 319- amino acids. Our previous study showed that hHole was strongly expressed in adult heart and may act as a suppressor of extracellular signal-regulated kinases (ERKs), overactivation of which contributed to pathological cardiac hypertrophy. In this study, it was observed that Hole expression was up-regulated in murine hypertrophic hearts. In a cardiac specific transgenic mouse model, it was observed that overexpression of hHole specifically in heart attenuated cardiac hypertrophy and fibrosis induced by isoproterenol (ISO), with blunted transcriptions of ERK1/2, total ERK1/2 proteins and phosphorylated ERK1/2 (p-ERK1/2) levels. Furthermore, overexpression of hHole in mice by hydrodynamic tail-vein injection with hHole plamids also inhibited cardiac hypertrophy induced by ISO. Our work identified hHole as a novel repressor of cardiac hypertrophy, and provided new insights into the possible target for the prevention or treatment of cardiac diseases.

Longevity Assurance 5 (LASS5), a member of the LASS/Ceramide Synthases family, synthesizes C16-ceramide and is implicated in tumor biology. However, its precise role is not yet well understood. A yeast two-hybrid screen was performed using a human cDNA library to identify potential LASS5- interaction partners. One identified clone encodes succinate dehydrogenase subunit B (SDHB). Mammalian two-hybrid assays showed that LASS5 interacts with SDHB, and the result was also confirmed by GST pull-down and coimmunoprecipitation assays. The C-terminal fragment of SDHB was required for the interaction. LASS5 and SDHB were co-localized in COS-7 cells. LASS5 and SDHB expressions were found to be up-regulated in neuroglioma tissue. Transfection assays showed that LASS5 or SDHB expression repressed p53 or p21 reporter activity, respectively. Simultaneous LASS5 and SDHB expression resulted in stronger repression of p53 and p21 reporter activity, suggesting that LASS5 and SDHB interaction may synergistically affect transcriptional regulation of p53 and p21. Our data provide new molecular insights into potential roles of LASS5 and SDHB in tumor biology.

Preparation of berberine hydrochloride (B-Cl) imprinted polymers (MIPs) based on surface imprinting technique with silica gel as sacrificial support material was performed successfully by using B-Cl as template, methacrylic acid (MAA) and ethylene glycol dimethacrylate (EGDMA) as functional monomer and cross-linker, respectively. The prepared polymers were characterized by Fourier transmission infrared spectrometry (FTIR) and scanning electron microscopy (SEM). Adsorption behavior of the MIPs for the template and its structural analogues was investigated. Sites distribution on the surface of MIPs was explored by using different isotherm adsorption models and thermodynamic parameters for the adsorption of B-Cl on the MIPs determined. Sample application and reusability for the MIPs was also evaluated. Results indicated the strong adsorption and high selectivity of the MIPs for B-Cl. Saturated adsorption capacity reached 27.2 μmol g −1 and the selectivity coefficient of the MIPs for B-Cl relative to jatrorrhizine hydrochloride (J-Cl) and palmatine palmatus hydrochloride (P-Cl) are 3.70 and 6.03, respectively. In addition, the MIPs were shown with good reusability and selectively retention ability in sample application.

Compounds Sr4Eu2Ti4Nb6O30 and Sr5EuTi3Nb7O30 with filled tetragonal tungsten bronze structure were prepared, and the dielectric characteristics and ferroelectric transition were investigated. Both ceramics displayed weak frequency dependence in room temperature dielectric constant, which decreased from 125 to 118 for Sr4Eu2Ti4Nb6O30, from 206 to 195 for Sr5EuTi3Nb7O30 in the frequency range of 10 kHz to 1 MHz. The present ceramics showed a diffuse ferroelectric phase transition. The frequency independent transition temperature (Tm) indicated the above compounds had no relaxor property. The diffuseness (γ) was 1.45 and 1.64 for Sr4Eu2Ti4Nb6O30 and Sr5EuTi3Nb7O30 respectively. The weak ferroelectric of the present materials are indicated from the P-E hysteresis loops, and a small 2Pr of 0.596 μC/cm2 and 0.068 μC/cm2 were observed for Sr4Eu2Ti4Nb6O30 and Sr5EuTi3Nb7O30 respectively.

Polycrystalline samples of Ba4Ln2Fe2Ta8O30 (Ln = La and Nd) were prepared by a high temperature solid-state reaction technique. The formation, structure, dielectric and ferroelectric properties of the compounds were studied. Both compounds are found to be paraelectrics with filled tetragonal tungsten bronze (TB) structure at room temperature. Dielectric measurements revealed that the present ceramics have exceptional temperature stability, a relatively small temperature coefficient of dielectric constant (τ e ) of −25 and −58 ppm/°C, with a high dielectric constant of 118 and 96 together with a low dielectric loss of 1.2 × 10−3 and 2.8 × 10−3 (at 1 MHz) for Ba4La2Fe2Ta8O30 and Ba4Nd2Fe2Ta8O30, respectively. The measured dielectric properties indicate that both materials are possible candidates for the fabrication of discrete multilayer capacitors in microelectronic technology.

Ba4Ln2Fe2Nb8O30 (Ln = Eu and Gd) ceramics were synthesized by high temperature solid state reaction. The phase composition, microstructure, dielectric and ferroelectric properties of them were characterized. Both ceramics adopt filled tetragonal tungsten bronze structure at room temperature. The diffusive phase transitions were observed for Ba4Eu2Fe2Nb8O30 and Ba4Gd2Fe2Nb8O30 around 163°C and 150°C, respectively. Ba4Eu2Fe2Nb8O30 and Ba4Gd2Fe2Nb8O30 ceramics are classical ferroelectrics at room temperature and show high dielectric constant of 118 and 160 and low dielectric loss 0.022 and 0.054 at 1 MHz, respectively. The remnant polarizations (2Pr) are 3.9μC/cm2 for Ba4Eu2Fe2Nb8O30 and 1.71μC/cm2 for Ba4Gd2Fe2Nb8O30.

Two novel La3+ and Ti4+ cosubstituted Sr3LaNb3O12 ceramics, Sr2La2TiNb2O12 and SrLa3Ti2NbO12, were prepared and the effect of substitution on the microwave dielectric properties was investigated. Results showed that as the amounts of substitution increased, dielectric constant (εr) increased from 36 to 41, and temperature coefficient of resonant frequency (τf) improved from −9 to 3 ppm/°C, whereas the quality factor (Q×f) decreased from 45,000 to 33,600 GHz. A temperature-stable microwave dielectric ceramics SrLa3Ti2NbO12 with τf of 3 ppm/°C, εr of 41, Q×f of 33,600 GHz was obtained; it might be a promising candidate for practical application in base stations if the quality factor is enhanced beyond 40,000 GHz.

Two new tungsten bronze ferroelectrics Sr 6− n Pr n Ti n Nb 10− n O 30 ( n = 1, 2) were synthesized and characterized. Sr 5 PrTi 3 Nb 7 O 30 and Sr 4 Pr 2 Ti 4 Nb 6 O 30 had tetragonal filled tungsten bronze structure at room temperature, and exhibited weak ferroelectric nature with remnant polarizations ( P r ) of 0.81 and 0.8 μC cm −2 , respectively. Sr 5 PrTi 3 Nb 7 O 30 showed diffused relaxor behavior with the Curie temperature T c at around 70 °C (at 1 MHz), while Sr 4 Pr 2 Ti 4 Nb 6 O 30 showed diffused normal ferroelectric transition with T c at 182 °C . Their dense ceramics had dielectric constant of 550 and 325, and dielectric loss (tan δ ) of 0.05 and 0.006 for Sr 5 PrTi 3 Nb 7 O 30 and Sr 4 Pr 2 Ti 4 Nb 6 O 30 at 1 MHz, respectively. Heterogeneous mixtures of the two compounds might be used to fabricate temperature-stable dielectrics.

The tetragonal tungsten bronze (TTB)-structured Ba4Sm2Fe2M8O30 (M=Nb, Ta) dielectrics were prepared and investigated. Dielectric and ferroelectric behaviors revealed that the niobate and the tantalate display ferroelectric and paraelectric nature at room temperature (RT), respectively. The dielectric spectrum showed that Ba4Sm2Fe2Ta8O30 ceramic has a high dielectric constant (∼97), a comparatively low temperature coefficient of dielectric constant (∼−105 ppm/°C), and a low dielectric loss (∼10−3) (at 1 MHz). These results indicated that the present tantalate might be a new temperature-compensating ceramic.

Polycrystalline samples of Sr5PrTi3Ta7O30 (SPTT) and Sr5EuTi3Ta7O30 (SETT) compounds were prepared by high-temperature solid-state reaction method and their formation, structure and dielectric properties were studied. They are found to be ferroelectric phase of filled tetragonal tungsten bronze (TB) structure at room temperature and undergoes diffuse type of ferroelectric-paraelectric phase transition around 34 °C and 31 °C, respectively. At 1 MHz SPTT exhibits high dielectric constants of 177 and low dielectric losses of 3.5×10−4 and SETT has high dielectric constants of 125 and low dielectric losses of 2.4×10−3.

Polycrystalline Sr5LnTi3Ta7O30 (Ln=La, Nd, Sm and Y) ceramics were prepared as single-phase materials through conventional solid-state ceramics method. The structure was characterized by X-ray diffraction method and scanning electron microscopy (SEM). The dielectric properties were measured from room temperature to 400 °C. All compounds are paraelectric phases adopting the filled tetragonal tungsten bronze (TB) structure at room temperature. At 1 MHz their dielectric constant (er) varied from 109 to 139, dielectric loss changed from 0.003 3 to 0.005 8, and the temperature coefficients of the dielectric constant (τe) moved from −710 to −880×10−6 °C−1.

Polycrystalline samples of Sr 4 Pr 2 Ti 4 Ta 6 O 30 (SPTT) and Sr 4 Eu 2 Ti 4 Ta 6 O 30 (SETT) were prepared by a high temperature solid-state reaction technique. The formation, structure, dielectric and ferroelectric properties of the compounds were studied. Sr 4 Eu 2 Ti 4 Ta 6 O 30 is found to be a ferroelectric phase with filled tetragonal tungsten bronze (TB) structure at room temperature and undergoes a diffuse type ferroelectric–paraelectric phase transition around 90 °C with relaxor properties, while Sr 4 Pr 2 Ti 4 Ta 6 O 30 belongs to paraelectric phase with TB structure at room temperature. At 1 MHz, SPTT exhibits a high dielectric constant of 181 and a low dielectric loss of 3.6 × 10 −3 with a negative temperature coefficient of the dielectric constant ( τ ɛ ), and SETT has a high dielectric constant of 192 and low dielectric loss of 7.7 × 10 −3 with a positive τ ɛ at room temperature, and heterogeneous mixtures of SPTT and SETT or a solid solution between them might be used to manufacture a tungsten bronze-structured temperature-stable dielectrics.

The dielectric ceramics Ba4Pr2Fe2Ta8O30 and Ba4Eu2Fe2Ta8O30 with a tetragonal tungsten bronze structure were synthesized and characterized. Dielectric and ferroelectric behaviors indicated that the ceramics are paraelectric above room temperature. Dielectric measurement showed that the present ceramics have high-temperature stability, a comparatively low temperature coefficient of dielectric constant (τɛ) of −30 and −63 ppm/°C, with a high dielectric constant (ɛr) of 110 and 87.6 together with a low dielectric loss (tan δ) of 0.0010 and 0.0012 (at 1 MHz) for Ba4Pr2Fe2Ta8O30 and Ba4Eu2Fe2Ta8O30, respectively. These results indicated that the Ba4Ln2Fe2Ta8O30 (Ln=Pr, Eu) ceramics might be promising in temperature-stable multilayer ceramic capacitors.

The title compounds are prepared by solid state reaction of SrCO3, Ln2O3 (Ln: Pr, Eu), TiO2, and Ta2O5 (1450—1500 °C, 4 h) and characterized by XRD, SEM, and dielectric measurements.

A novel series of single-phase polycrystalline ceramics Sr4−mLamTim−1Ta4−mO12 (m=1, 2, 3) were prepared through the solid-state ceramic route. All of them adopt A4B3O12-type cation-deficient hexagonal perovskite structure. The microwave dielectric properties can be tuned by controlling the composition or the value of m. As m increases, the dielectric constant (ɛr) of the ceramic increases from 30 to 40.1 and the quality factor (Q×f) enhances from 16 050 to 42 130 GHz, and the temperature coefficient of resonant frequency (τf) improves from −43 to −8 ppm/°C.

A series of the twinned 8H hexagonal perovskites in the Ba4LiNb3−xTaxO12 (x=0–3) system were synthesized by the conventional solid-state reaction method. Ba4LiNb3−xTaxO12 solid solutions were single phase in the whole range of x values. The ceramics exhibit perfect microwave dielectric properties with relative permittivity, ɛr∼28–37, high quality factor, Q×f∼37 000–104 000 GHz, and temperature coefficient of resonant frequency, τf∼+25–+65 ppm/°C.