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Long-term application of chemical fertilizer poses an environmental threat to belowground ecosystems. However, the impact of nitrogen (N) or phosphorus (P) fertilizers on soil biodiversity and the conditions of soil food web remains largely unknown. Soil nematodes are the most abundant multicellular soil animals and serve as excellent bioindicators of soil. Here, we investigated soil nematode communities and food web structure in a long-term experiment with different application rates of N and P fertilizers in northeast China. The application of N and P fertilizers increased the abundance of bacterivores but suppressed the abundance of omnivores and predators. The abundance of bacterivores exhibited an increasing trend, while that of omnivores and predators showed a decreasing trend with increasing rates of N and P fertilizers. Plant parasites displayed a decreasing trend in response to N fertilizer, but not to P fertilizer. N and P fertilizers also altered nematode functional guild composition, with N fertilizer increasing the abundance of Ba1, and P fertilizer increasing the abundance of Fu2 and Ba3. Nonmetric multidimensional scaling (NMDS) analysis revealed apparent successions of nematode communities from no fertilizer soils to high rates of N or P fertilizer soils at both the genus and functional guild levels. Furthermore, N and P fertilizers resulted in different nematode communities. In terms of nematode food web indices, N fertilizer increased the enrichment index (EI) but reduced the channel index (CI) and structure index (SI), whereas P fertilizer only reduced the SI value. High rates of N and P fertilizers increased the respired carbon of bacterivores but reduced the respired carbon of predators. Mantel tests revealed significant correlations between soil properties and the community composition of both fungivores and omnivores. Among all soil properties, available phosphorus (AP) had the greatest influence on the community structure of soil nematodes. Our findings indicate that N fertilizer has a powerful effect on nematode food web structure, while P fertilizer exerts a stronger effect on soil nematode community composition. [ABSTRACT FROM AUTHOR]

Background and aims: Understanding the effects of livestock grazing on the ecosystem biomass and soil nitrogen processes of grassland ecosystems is critical to improving knowledge on the mechanisms underlying grassland degradation and accurately assessing the influence of grazing management on grassland functions. Methods: We examined the interannual patterns of ecosystem biomass and soil nitrogen mineralization in response to cattle grazing in a Chinese meadow steppe. The soil core incubation method was employed for soil N transfer estimation, whilst the fumigation extraction method, a modified Baermann funnel method and harvest method were used for various measurements of ecosystem biomass parameters. Results: We found that cattle grazing caused consistent significant increases in soil temperature, irrespective of the stocking rate and year, whereas significant effects on soil moisture and edaphic properties were observed only in individual years and/or at specific stocking rates. Consistent positive effects at moderate stocking rates were observed for aboveground net primary production and soil nematode biomass in all study years. The across stocking rate pattern of N mineralization in response to cattle stocking appeared to be year-specific, although negative effects were found in most cases. In contrast, the interannual pattern of N mineralization was determined principally by the interannual patterns in precipitation and soil moisture and was much less affected by cattle grazing. Conclusions: Soil N mineralization in this meadow steppe was affected by cattle grazing via two major mechanisms, i.e., its effects on the aboveground net primary production (ANPP) and thus the quantity of plant litter input into the soil and its effects on soil temperature and moisture. Overall, our study spanned the longest consecutive years with the broadest range of stocking rates thus far of its kind, which revealed for the first time that the soil nitrogen mineralization pattern with respect to stocking rate was year-specific. Our findings have important implications for adaptive management and sustainable utilization of Chinese grasslands. [ABSTRACT FROM AUTHOR]

Aims: Grazing is a key driver of plant communities and soil functions in grassland ecosystems. Soil nematodes play a vital role in soil ecological functions. The aim of this study was to explore how grazing shapes soil nematode community in different soil layers. Methods: We investigated the composition, abundance, diversity, metabolic footprint, and food web metrics of soil nematodes over a gradient of grazing in the 0–10 cm and 10–20 cm soil layers in a meadow steppe. The relationships between nematode community structure and biotic and abiotic factors were analyzed by principal component analysis and structural equation model analysis. Results: Light grazing increased the abundance of total soil nematodes by 18.5%. Intensive grazing decreased the carbon used in production and metabolic footprints of plant parasites, fungivores, and total soil nematodes in 0–10 cm soils. There was no difference in the carbon used in production and metabolic footprints of soil nematodes among different grazing intensities in the 10–20 cm soil layer. Soil moisture, aboveground biomass, belowground biomass and Shannon diversity of grass contributed more to changes in soil nematode composition in both soil layers. In the 0–10 cm soil layer, grazing directly and indirectly affected soil nematode diversity via soil moisture and aboveground biomass, while grazing directly affected soil nematode diversity in 10–20 cm soil layer. Conclusions: Our results indicate that increasing soil depth can weaken the effect of grazing intensities on soil nematode fauna. Grazing affected the soil nematode community structure via different paths in different soil layers. [ABSTRACT FROM AUTHOR]

The FMRFamide-like peptides (FLPs) represent the largest family of nematode neuropeptides and are involved in multiple parasitic activities. The immunoreactivity to FMRFamide within the nervous system of Heterodera glycines , the most economically damaging parasite of soybean [ Glycine max L. (Merr)], has been reported in previous research. However, the family of genes encoding FLPs of H. glycines were not identified and functionally characterized. In this study, an FLP encoding gene Hg-flp-22 was cloned from H. glycines , and its functional characterization was uncovered by using in vitro RNA interference and application of synthetic peptides. Bioinformatics analysis showed that flp-22 is widely expressed in multiple nematode species, where they encode the highly conserved KWMRFamide motifs. Quantitative real-time (qRT)-PCR results revealed that Hg-flp-22 was highly expressed in the infective second-stage juveniles (J2s) and adult males. Silencing of Hg-flp-22 resulted in the reduced movement of J2s to the host root and reduced penetration ability, as well as a reduction in their subsequent number of females. Behavior and infection assays demonstrated that application of synthetic peptides Hg-FLP-22b (TPQGKWMRFa) and Hg-FLP-22c (KMAIEGGKWVRFa) significantly increased the head movement frequency and host invasion abilities in H. glycines but not in Meloidogyne incognita. In addition, the number of H. glycines females on the host roots was found to be significantly higher in Hg-FLP-22b treated nematodes than the ddH2O-treated control J2s. These results presented in this study elucidated that Hg-flp-22 plays a role in regulating locomotion and infection of H. glycines. This suggests the potential of FLP signaling as putative control targets for H. glycines in soybean production. [ABSTRACT FROM AUTHOR]

Crop monoculture affects soil microbial community structure and diversity, but it is unclear which differences occur in microbial functions after the alteration of the bacterial community during crop monoculture. We investigated the diversity, functional groups and metabolic functions of bacteria under soybean rotation (RS), 2-year (SS) and 27-year (CS) soybean monoculture systems using high-throughput sequencing and functional prediction based on FAPROTAX and the Kyoto Encyclopedia of Genes and Genomes (KEGG). Original soil sample (OS) was taken as a reference point. Our results showed that CS had a lower abundance of the bacterial amoA gene than either RS or SS. Bacterial community differed more in OS than that in RS, SS and CS, and SS and CS had similar bacterial community and that they differed from RS. CS showed a lower relative abundance of predicted functional groups in terms of aerobic chemoheterotrophy, nitrate reduction and photoheterotrophy. KEGG annotation showed greater negative effects on the bacterial functional metabolism than positive effects in CS compared to RS. Redundancy analysis indicated that the predicted functional groups might be related to organic carbon and total nitrogen concentration, and that KEGG pathways were mainly affected by soil pH and available nitrogen. Abbreviations RS: soybean rotation; SS: two-year soybean monoculture; CS: long-term soybean monoculture; AOB: ammonia-oxidizing bacteria; qPCR: quantitative real-time PCR; OTUs: operational taxonomic units; SOC: soil organic carbon; TN: total nitrogen; AN: available nitrogen; TP: total phosphorus; AP: available phosphorus; AK: available potassium; PCoA: Principal coordinate analysis; KEGG: the Kyoto Encyclopedia of Genes and Genomes; RDA: redundancy analysis. [ABSTRACT FROM AUTHOR]

The aim of the present study was to explore whether the hypertrophy of H9C2 cardiomyocytes was induced by high glucose, to investigate whether the calcium channel inhibitor (Norvasc) could inhibit this process and to clarify the possible signaling pathways. The morphology of H9C2 cells was observed under an optical microscope, and the cell surface area was measured by Image Pro Plus 6.1 software. Furthermore, fluorescence spectrophotometry was used to detect intracellular calcium concentration ([Ca2+]i). ELISA was performed to detect calcineurin (CaN) activity; reverse transcription-quantitative PCR and western blotting were performed to detect the mRNA and protein expression levels of CaN Aβ subunit (CnAβ), nuclear factor of activated T cells 3 (NFAT3) and β type myosin heavy chain (β-MHC). Cell size was increased with the increase in glucose concentration of culture medium at 48 and 72 h, respectively, and decreased with the addition of Norvasc compared with those without Norvasc (P<0.05). There was no significant difference in cell size with the addition of Norvasc compared with cells cultured with 5 mM glucose (P>0.05). The average [Ca2+]i activity of single cells in the 48- and 72-h culture groups treated with 50 mM glucose was significantly higher than cells treated with 5 mM glucose (P<0.05); and the fluorescent value of average [Ca2+]i activity of single cells was lower, following the addition of Norvasc than that without Norvasc (P<0.05). CaN activity in the 48- and 72-h culture group treated with 50 mM glucose was markedly higher than that treated with 5 mM glucose, and the activity of CaN notably decreased with the addition of Norvasc compared with those without Norvasc. The mRNA and protein expression levels of CnAβ, NFAT3 and β-MHC in the 48- and 72-h culture groups treated with 50 mM glucose were all significantly higher than those treated with 5 mM glucose (P<0.05). The mRNA and protein expression of CnAβ, NFAT3 and β-MHC cultured with 50 mM glucose were significantly decreased following the addition of Norvasc (P<0.05). Thus, the calcium channel inhibitor Norvasc may inhibit high glucose-induced hypertrophy of H9C2 cardiomyocytes by inhibiting the Ca2+-CaN-NFAT3 signaling pathway. [ABSTRACT FROM AUTHOR]

Zinc gallogermanate nanoparticles have been synthesized by a sol–gel process with adjustment of Zn2+, Ga3+, and Ge4+ ratios and subsequent sintering at 1000 °C. The resulting X-ray diffractograms can be simulated by variation of the ratios α, β, and γ in the standard cards of αZnGa2O4–βZn2GeO4–γGeO2. Similarly, the FT-IR and Raman vibrational spectra are sums of the spectra of the individual components. The major difference in our synthesis of the ratio α:β:γ = 1:1:1 compound, ZGGO, from previous studies is the contribution of Zn2GeO4 in the rhombohedral lattice system and not the cubic phase. Photoluminescence and electron spin resonance spectra supply sensitive analyses of our samples and show the presence of zinc and oxygen vacancies, with the latter playing an important role in emission. In particular, a tunable visible emission band is discovered which can be deconvoluted into several Gaussian components. The lowest energy band, at ∼520 nm, gives the strongest persistent luminescence, and it is tunable by adjusting the ionic ratios in the samples. The persistent luminescence decay can be fitted by biexponential functions with five free parameters, but the normalized persistent luminescence decay can also be fitted by a hyperbolic function with one free parameter, representing an average rate constant. This implies a fairly unimodal distribution of trap–acceptor distances and/or orientations. The rate constant decreases with measurement time because deeper traps are being emptied. The fitted average rate constants, when monitoring persistent luminescence at different energies, display the persistent luminescence spectrum. Doping the zinc gallogermanates with chromium enables the relative intensity of green/NIR persistent luminescence bands to be tuned by adjusting the Cr3+ content. A potential application of the dual persistent luminescence is in simultaneous photosensitization and bioimaging. [ABSTRACT FROM AUTHOR]

Summary: The aim of this study was to examine the impact of water extracts of Narcissus tazetta bulb on hatching, behaviour and mortality of second-stage juveniles (J2) and reproduction of the soybean cyst nematode (SCN; Heterodera glycines) in laboratory and glasshouse assays. Results demonstrated that N. tazetta bulb extracts did not affect hatching but significantly reduced J2 motility and nematode attraction to the soybean root tip, and resulted in considerable nematode mortality relative to the control. J2 exposure to different concentrations of bulb extracts caused 59-93% reduction in nematode reproduction on soybean roots. Compared with the monoculture control, soybean- N. tazetta intercropping in a pot trial reduced SCN reproduction by 37%. In addition, N. tazetta bulb powder as a soil amendment is effective in controlling SCN reproduction. Thus, the results suggest that N. tazetta bulb extract or derived active compounds may be considered as potential natural nematicides against SCN. [ABSTRACT FROM AUTHOR]

Many approaches have contributed to improving the luminescence properties of phosphors, including surface coating, direct reduction and charge compensation, which are involved in reducing the inner or surface defects of luminescent particles. In this study, we propose a cation vacancy repair strategy to successfully improve the orange-yellow luminescence properties of the Sr9Mg1.5(PO4)7:Eu2+ phosphor. The main idea of the strategy is that introducing K+ repairs the vacancy at the Mg(1) site according to the formula UGRAPHIC DISPLAY="INLINE" ID="UGT1" SRC="UGT1"/. The preferred substitution of the large Mg(1) site by K+ is supported by theoretical calculations. As a result, the luminescence of the repaired phosphate phosphor was enhanced by 2.5 times, and the internal and external quantum efficiency significantly increased by 50.5% and 55.4%, respectively. Additionally, the thermal stability was also a little improved. The enhancement mechanisms for luminescence are discussed in detail based on investigations of the microstructure, luminescence spectra, decay curves and concentration using various analysis techniques. We find that low luminescence efficiency is due to the existence of vacancy defects in the phosphor. Through using the repaired Sr9MgK(PO4)7:Eu2+ phosphor, a white LED package demonstrated a low correlated color temperature (∼2900 K), high color rendering index (∼90) and R9 ＞ 91. We expect that the strategy proposed herein would improve luminescence for other phosphors with vacancy defects. [ABSTRACT FROM AUTHOR]

All reported layered metal hydroxides have brucite‐like metal‐hydroxyl host layers, and the discovery of other types of layered metal hydroxides could significantly extend the layered metal hydroxide families, which is meaningful in both theory and applications. Here, through hydroperoxyl anion coordinated In3+ cations as a precursor, a new layered indium hydroxide was synthesized, where only a three‐dimensional cubic phase had existed before. The layer of the product exhibits an unusual structure where In(OH)6 octahedra share edges and vertexes with each other to form layers, which is completely different from the common edge‐sharing brucite‐like metal‐hydroxyl layers. By investigating the formation mechanism, the new layered structure is found to be formed by changing the traditional crystallization path through the hydroperoxyl anion coordinated intermediates. Many other new phases could also be discovered by following the same intrinsic principle. Layer cake: Only cubic In(OH)3 can be synthesized by traditional methods. A second crystalline phase of indium hydroxide, a layered compound, was prepared here through the assistance of H2O2. The structure of the layer is completely different from the layer of traditional brucite‐like layered metal hydroxides. [ABSTRACT FROM AUTHOR]

Ultrathin nanomaterials have aroused much attention because of their enhanced photocatalytic activities. However, conventional exfoliation methods require a complex preparation procedure, and the intercalated cationic organic compounds are difficult to remove. Herein, HNb3O8 nanobelts were successfully prepared via a one-pot hydrothermal route by using POM precursors. With the aid of acetic acid, Cu ions were easily loaded through a one-pot synthesis, and they significantly enhanced the photocatalytic water splitting performance (8 times higher than that of unmodified nanobelts). Based on the XPS results, we found that the Cu ions had mixed oxidation states of Cu+/Cu2+, and the ratio did not change after calcination at 350 °C, indicating that some of the Cu+ ions were inserted between the layers. The role of Cu in promoting hydrogen evolution activities was attributed to the improvement in the separation of photo-induced carriers and the photo-to-electron conversion efficiency; these observations were confirmed by the analyses of photocurrent response and photoluminescence. [ABSTRACT FROM AUTHOR]

The crystal structures and their changing trend in the strontium–bismuth-oxide system are critical for the studies of the related systems and their applications. The crystal structure of Sr3Bi2O6 was obtained for the first time in the space group of R3̅ with a huge unit cell of a = b = 25.1146(19) Å and c = 18.3685(16) Å and all bismuth ions are Bi3+ forming [BiO3] trigonal pyramids. Sr3Bi2O6 is a key compound for the structural change trend in the SrO–Bi2O3 binary oxide system at 1000 °C. With a decrease in the bismuth content, its valence state changes from +3 to +5 and Bi–O polyhedra changes from connected to isolated before Bi(v) appearance. In the system, the boundary of the solid solution β-phase (Sr1−xBixO1+0.5x) at 900 °C was also determined accurately as 0.770 ≤x≤ 0.862, experimentally. [ABSTRACT FROM AUTHOR]

AlPO4-5 is the most extensively studied material in exploring the crystallization mechanism of aluminophosphate molecular sieves, and it can be synthesized using 4-dimethylaminopyridine (DMAP) as an organic structure-directing agent (OSDA). Achieving the AlPO4-5 intermediate in the crystalline form would be of great importance and significance for this purpose. In this study, we proposed a concept that by carefully regulating the synthesis conditions, crystalline alumimophosphate intermediates could be rationally prepared. A crystalline AlPO4-5 intermediate, (C7H11N2)2(H3O)(Al3P4O16)·(H2O)2.5 (1), was, therefore, synthesized by significantly increasing the amounts of orthophosphoric acid and DMAP. The intermediate 1 consists of alternating organic DMAP and inorganic [Al3P4O16]3− layers with abundant hydrogen bonds and can transform to the AlPO4-5 framework upon heating in air or through a steam-assisted conversion (SAC) method. To unravel the role of DMAP in the transformation, pure AlPO4-5 (2) was also synthesized by altering the synthesis conditions. The supramolecular assembly templating (SAT) effects of DMAP in 1 and 2 were verified via fluorescence spectra. Thus, the π–π stacking interactions between the DMAP molecules and the abundant hydrogen bonds between the adjacent layers are considered to be important for the phase transformation of 1. This crystalline intermediate would promote the understanding of the crystallization mechanism in the system of aluminophosphate molecular sieves. [ABSTRACT FROM AUTHOR]

Spectral adjustment based on the energy transfer process between donor–acceptor pairs has been routinely used to design luminescent materials with different colours and absorption bandwidths. This work reports an alternative way to design new luminescent materials based on a site-selected energy transfer mechanism using high precision control of dopants. The new material Sr2SiO4:Eu2+,Pr3+ has been successfully synthesized to show versatile emissions under site-selected excitation. We demonstrate an efficient site-selected energy transfer process from Eu2+ to Pr3+ and that dual-mode spectral control can be achieved by choosing Eu2+ in Sr2SiO4 as a yellow emission centre and Pr3+ as a red and near infrared emission centre. Therefore a yellow-to-orange phosphor has been realized with excitation-dependent adjustable red and near infrared emissions. The site-selected spectral adjustments and energy transfer mechanism are investigated in detail. This work suggests the design and synthesis of new materials for application in solar cells and white LED devices. [ABSTRACT FROM AUTHOR]

The soybean cyst nematode (SCN) is a major yield-limiting pest of soybean. In this study, experiments were conducted to examine the diversity of parasitic fungi from SCN associated with disease-suppressive soil fields in Northeast China. Soil samples were collected from three fields under different rotation systems that were established in 1991: (1) a continuous long-term cropping field with soybean (SSSS) that had been shown to be SCN-suppressive, (2) cycles of three-year rotation with corn, soybean, and wheat (WCS), and (3) continuous cropping field with three-year cycles of two years soybean and one-year corn (SSC). In the traditional method result, cyst densities of SCN declined as increase of parasitic fungi, and the percentage of parasitic fungi associated with cyst of SCN was higher in SSSS field than other two fields. Polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) also showed that parasitic fungi of SCN were also increased in SSSS field, compared with the other two fields. Principal component analysis based on PCR-DGGE data revealed that fungal communities on cysts could be divided into three groups: one group occurred in SSSS, and the other two groups were in WCS and SSC fields, respectively. Long-term cropping with soybean monoculture in the black soil field might increase parasitic fungi of SCN. These fungal communities may play an important role in the ecological suppression of SCN in disease-suppressive soil. [ABSTRACT FROM AUTHOR]

Y3+–Mg2+ pairs were incorporated into the Ca3Sc2Si3O12 for Ca2+–Sc3+ sites to investigate their structural and optical properties systematically, their potential applications in white light-emitting diodes, as well as the coexistent shrinkage effects of the first sphere and the second sphere based on the Rietveld refinement analysis of X-ray diffraction data. Due to the substitution of Y3+–Mg2+, an obvious red shift of the emission occurs. CIE chromaticity coordinates, quantum efficiency as well as thermal stability suggest that this double substitution is an efficient way to tune the luminescence properties of phosphors. The white LED devices were also successfully fabricated which demonstrates that such a kind of double substitution will be a promising way to broaden the applications of phosphors in advanced lighting in the future. [ABSTRACT FROM AUTHOR]

An intense blue-emitting phosphor, Ba4OCl6:Eu2+, was developed by a solid state reaction at low synthesis temperature. The photoluminescence excitation and emission spectra, concentration effect, thermal-dependent luminescence quenching properties, chromaticity shift, activity energy and luminous efficiency of radiation are investigated. These results show that Eu2+ exhibits a broadband excitation extending from 250 to 400 nm and emits an intense blue light at 450 nm with a tiny colour chromaticity shift in the temperature range of 350–490 K. The external quantum efficiency of Ba3.97OCl6:Eu0.032+ is about 26.6%. It demonstrates that Eu2+ doped Ba4OCl6 can be excited by an n-UV LED chip and is an effective blue-emitting phosphor potentially useful in white LEDs. [ABSTRACT FROM AUTHOR]

A series of LiCaBO3:Ce3+/Pr3+ phosphors were prepared by a high-temperature solid state reaction method. A structure refinement for the LiCaBO3 compound was performed based on powder X-ray diffraction (XRD) data. The energies of the crystal field split excited 5d states of Ce3+ and Pr3+ in LiCaBO3 were determined from synchrotron radiation VUV-UV excitation spectra. Furthermore, the influence of the doping concentration and temperature on the emission properties of Ce3+ was investigated, and the vacuum referred binding energy (VRBE) scheme for all lanthanide 4f and 5d states in LiCaBO3 was constructed to estimate the thermal activation energy of Ce3+ luminescence quenching. The Pr3+ to Ce3+ energy transfer (ET) and its influence on luminescence decays of Pr3+ and Ce3+ were studied in detail. Finally, the X-ray excited luminescence spectra were measured to evaluate the possible X-ray detection applications. [ABSTRACT FROM AUTHOR]

The 8-layered shifted hexagonal perovskite compound Ba8ZnNb6O24 was isolated via controlling the ZnO volatilization, which features long-range B-cation ordering with nanometer-scale separation by ∼1.9 nm of octahedral d10 cationic (Zn2+) layers within the purely corner-sharing octahedral d0 cationic (Nb5+) host. The long-range ordering of the B-site vacancy and out-of-center distortion of the highly-charged d0 Nb5+ that is assisted by the second-order Jahn–Teller effect contribute to this unusual B-cation ordering in Ba8ZnNb6O24. A small amount (∼15%) of d10 Sb5+ substitution for Nb5+ in Ba8ZnNb6−xSbxO24 dramatically transformed the shifted structure to a twinned structure, in contrast with the Ba8ZnNb6−xTaxO24 case requiring 50% d0 Ta5+ substitution for Nb5+ for such a shift-to-twin transformation. Multiple factors including B-cationic sizes, electrostatic repulsion forces, long-range ordering of B-site vacancies, and bonding preferences arising from a covalent contribution to the B–O bonding that includes out-of-center octahedral distortion and the B–O–B bonding angle could subtly contribute to the twin–shift phase competition of B-site deficient 8-layered hexagonal perovskites Ba8B7O24. The ceramics of new shifted Ba8ZnNb6O24 and twinned Ba8ZnNb5.1Sb0.9O24 compounds exhibited good microwave dielectric properties (εr∼ 35, Qf∼ 36 200–43 400 GHz and τf∼ 38–44 ppm/°C). [ABSTRACT FROM AUTHOR]

Eu2+ and Mn2+ coactivated β- Ca3( PO4)2 ( TCP) phosphors have been prepared by high-temperature solid-state reaction. The site occupation and photoluminescence properties of Eu2+ and Mn2+ have been identified and discussed in detail. The energy transfer from Eu2+ to Mn2+ in TCP: Eu2+, Mn2+ phosphors has been validated and demonstrated to be a resonant type via a dipole-quadrupole mechanism, and the critical distance ( R C) calculated by concentration quenching method is 21.76 Å. A color-tunable emission from violet-blue to red in TCP: Eu2+, Mn2+ phosphors can be realized via the energy transfer from Eu2+ to Mn2+ ions. [ABSTRACT FROM AUTHOR]

The effects of Ti substitution on the crystal chemistry and microwave dielectric properties of Ga1−xTa1−xTi2xO4 were investigated. GaTaO4 adopts a 1:1-ordered monoclinic α-PbO2 type structure. At 1300 °C the Ga1−xTa1−xTi2xO4 system formed a monoclinic α-PbO2 type solid solution when x≤ 0.05, and further Ti substitution in Ga1−xTa1−xTi2xO4 induced a phase transformation from α-PbO2 to rutile, leading to a rutile solid solution when x≥ 0.15. Within the intermediate composition range 0.075 ≤x≤ 0.1, a mixture of α-PbO2 and rutile phases formed, which gradually transformed into a single rutile phase upon being fired at 1350–1400 °C. At 1400 °C the compositions where x = 0–0.025 remained in monoclinic α-PbO2 type phases, while the x = 0.05 composition transformed into a rutile polymorph, implying that Ti substitution is favorable for stabilizing the high temperature rutile polymorph of GaTaO4 down to room temperature. The monoclinic Ga1−xTa1−xTi2xO4 (x = 0, 0.05) ceramics exhibited a low permittivity (εr) values of ∼16–20, high Qf values ∼45 000–68 000 GHz and large negative temperature coefficients of the resonance frequency, τf of −56 ppm °C−1 to −47 ppm °C−1. Ti substitution in Ga1−xTa1−xTi2xO4 increased εr to ∼40 and τf to ∼53 ppm °C−1 in the range x = 0–0.4, while the Qf values exhibited a tendency to decrease with Ti substitution. The rutile solid solution showed, for the first time, a tunable τf from a negative value to a positive value and optimum microwave dielectric properties were achieved for rutile Ga0.75Ta0.75Ti0.5O4: εr∼ 37, Qf∼ 30 000 GHz and τf∼ 4.4 ppm °C−1. The factors controlling the dielectric loss and τf in Ga1−xTa1−xTi2xO4 are discussed in terms of the polymorphism, defects, charge disorder and polarizability associated with the Ti substitution. [ABSTRACT FROM AUTHOR]

Soil fauna is an important component in soil ecosystems. This study tested whether conservation tillage or conventional tillage of a black soil (Udic Mollisol) field in Northeast China could affect its soil fauna communities. Two different conservation tillage systems, no-tillage (NT) and reduced tillage (RT), as well as a conventional rotary tillage system (CT), were chosen for this study. There were 4562 individuals isolated from this study, which included two orders and 35 families. Acariformes was the most abundant family and represented 91.56% of the total faunal abundance. The abundance and the number of faunal families were higher in conservation tillage systems than in the CT. The RT system had the highest individual number of soil fauna among three tillage methods. The faunal accumulation in the soil surface also was significantly higher in the two conservation tillage systems than in the CT. Our results indicate that the conservation tillage systems could protect the soil fauna in the soil ecosystem better than the CT. [ABSTRACT FROM AUTHOR]

Plant-parasitic nematodes can cause serious plant diseases and adversely affect crop production. We investigated the temporal and vertical dynamics of plant-parasitic nematodes in northeast China to determine if long-term fertilizer application suppresses the population of plant-parasitic nematodes and influences their vertical distribution in the black soil region. The long-term fertilizer application lasted for 14 years, and included three treatments: pig manure combined with chemical fertilizer (MCF), chemical fertilizer (urea and ammonium phosphate, CF), and no fertilizer (NF). A 3-year corn-wheat-soybean rotation was grown on the field site, soil samples were obtained in the corn phase and nematodes were extracted, identified and counted. Six plant-parasitic nematode genera with relative abundance over 0.1% were found in this study. Heterodera was the dominant genus in all three fertilizer treatments, and its relative abundance was highest in NF (45.4%) and lowest in MCF (32.8%). Fertilizer application had a significant effect on abundance of total soil nematodes but not on either plant-parasitic nematodes or Heterodera. Significant differences in the abundance of total soil nematodes, plant-parasitic nematodes and Heterodera were observed among soil depths and interaction of fertilizer × soil depth. Total soil nematodes were mainly distributed in the 0-20 cm soil layer, and plant-parasitic nematodes and Heterodera were mostly distributed in the 10-30 cm soil layer. Fertilizer application did not show a significant effect on plant-parasitic nematodes or Heterodera at any of the sampling depths from 0 to 80 cm. The results indicated that fertilizer has no effective control on plant-parasitic nematodes when dominant genera and their respective plant hosts exist in relatively high abundance. [ABSTRACT FROM AUTHOR]

Ba8 CuTa6 O24−δ ceramics possess exceptionally high microwave dielectric loss among the eight-layer twinned hexagonal perovskite Ba8 MTa6 O24 (M = Zn, Co, Ni, Mg, Cu) analogs. Impedance spectroscopy measurement demonstrates that the eight-layer Ba8 CuTa6 O24−δ ceramics show the electrical heterogeneous microstructure, consisting of leaky insulating grains and more resistive grain boundary regions. This induced internal barrier layer capacitance (IBLC) effects on Ba8 CuTa6 O24−δ ceramics. The heterogeneous electrical microstructure is associated with partial reduction of Cu2+ to Cu+ and oxygen loss during the sintering procedure and limited reoxidization along grain boundary regions on cooling. The existence of Cu+ in Ba8 CuTa6 O24−δ ceramic is confirmed by X-ray photoelectron spectroscopy measurement. The leaky insulating bulk property for the Ba8 CuTa6 O24−δ ceramics is compared with the highly insulating bulk behavior of other low dielectric loss analogs, which indicates that the significant defects of Cu+ and oxygen vacancies are responsible for the high microwave dielectric loss of the Ba8 CuTa6 O24−δ ceramics. [ABSTRACT FROM AUTHOR]

It is well known that crop monoculture can induce negative effects on soil ecosystems and crop productivity. However, little is known about how vegetable monoculture affects the soil nematode community structure and its relationship with vegetable yields. In this study, the composition, abundance, metabolic footprint, and ecological indices of soil nematodes are investigated in monocultures of pumpkin and melon. The relationships between nematode community structure and yields of pumpkin and melon were analyzed by linear regression. Both monoculture soils of pumpkin and melon suppressed the relative abundance of bacterivores but increased the relative abundance of plant parasites. Pumpkin monoculture soils decreased soil nematode diversity but increased the maturity index of plant parasites. Monoculture soils of pumpkin and melon decreased the metabolic footprint of lower- and higher-level trophic groups of the soil food web, respectively. Pumpkin and melon monoculture soils increased the food web indices channel index (CI) but decreased the enrichment index (EI) and the structure index (SI). The monoculture soils of pumpkin and melon led to a more fungal-dominated decomposition pathway and degraded soil food web conditions. The abundance of bacterivores and food web indices EI and SI were positively correlated with soil nutrients and pH, while the abundance of plant parasites and CI were negatively correlated with soil nutrients and pH. Paratylenchus was negatively correlated with pumpkin and melon yields and could be the potential plant parasites threatening pumpkin and melon productions. Redundancy analysis showed that monocultures of pumpkin and melon altered the soil nematode community via soil properties; total N, total P, alkeline-N, and pH were the main driving factors. [ABSTRACT FROM AUTHOR]

Maize is one of the most important crops in the world. Heilongjiang province has the largest maize area in China. Plant-parasitic nematodes are important agricultural pests, which cause huge economic losses every year and have attracted global attention. Potato rot nematode Ditylenchus destructor is a plant-parasitic nematode with a wide range of hosts and strong survival ability in different environments, which brings risks to agricultural production. In 2020, D. destructor was detected in seven maize fields in Heilongjiang province. Morphological identification and molecular approach were used to characterize the isolated D. destructor. The observed morphological and morphometric characteristics were highly similar and consistent with the existing description. The DNA sequencing on the D2/D3 region of the ribosomal DNA 28S and the phylogenetic analysis showed that D. destructor population obtained from maize and other isolates infesting carrot, sweet potato, and potato were in subclade I supported by a 96% bootstrap value. Additionally, the phylogenetic analysis of the ITS rRNA gene sequence further indicated that this D. destructor population from maize clustered in a clade I group and belonged to ITS rRNA haplotype C. An inoculation experiment revealed that D. destructor was pathogenic on the maize seedlings in pots and caused the disease symptoms in the stem base of maize seedlings. This is the first report of D. destructor causing stem rot of maize in Heilongjiang province, and contributes additional information on disease control and safe production of maize in the region. [ABSTRACT FROM AUTHOR]

Soil nematodes are one of the most important components in terrestrial ecosystems and the critical factor driving the belowground process. The grasslands of Northeast China have been subject to mowing for ages, which theoretically should have had substantial effects on the processes associated with soil nematodes. However, relevant studies have barely been conducted to date. This study examined variations in soil nematode abundance, biomass, diversity, and community structure, with respect to varying mowing frequencies. The results showed that a higher mowing frequency significantly reduced the abundance of soil nematodes, biomass, diversity, and community structure stability in the ecosystem, while intermediate mowing frequency enhanced these parameters to different extents. Our findings indicate that the changing patterns of the nematode indices with mowing frequency conform to the intermediate disturbance theory. This study provides a theoretical basis for formulating grassland-related management measures and maintaining the stability of grassland ecosystems. [ABSTRACT FROM AUTHOR]

CeNbO4+δ, a family of oxygen hyperstoichiometry materials with varying oxygen content (CeNbO4, CeNbO4.08, CeNbO4.25, CeNbO4.33) that shows mixed electronic and oxide ionic conduction, has been known for four decades. However, the oxide ionic transport mechanism has remained unclear due to the unknown atomic structures of CeNbO4.08 and CeNbO4.33. Here, we report the complex (3 + 1)D incommensurately modulated structure of CeNbO4.08, and the supercell structure of CeNbO4.33 from single nanocrystals by using a three-dimensional electron diffraction technique. Two oxide ion migration events are identified in CeNbO4.08 and CeNbO4.25 by molecular dynamics simulations, which was a synergic-cooperation knock-on mechanism involving continuous breaking and reformation of Nb2O9 units. However, the excess oxygen in CeNbO4.33 hardly migrates because of the high concentration and the ordered distribution of the excess oxide ions. The relationship between the structure and oxide ion migration for the whole series of CeNbO4+δ compounds elucidated here provides a direction for the performance optimization of these compounds. Materials with oxygen hyperstoichiometry received great attention in solid oxide fuel cells field because of the low activation energy of interstitial ion migration. Here the authors revealed the relationship between the structure and oxide ion migration for the whole series of CeNbO4+δ compounds. [ABSTRACT FROM AUTHOR]