长期绿肥翻压对西北旱地小麦籽粒矿质元素含量的影响

绿肥对保障作物高产、土壤培肥和养分高效利用有重要影响,但长期翻压绿肥对旱地小麦籽粒矿质元素的影响尚不清楚。故依托甘肃武威25年长期定位试验,采集试验中不施肥、化肥和绿肥3个处理的小麦成熟期籽粒样品,利用电感耦合等离子体质谱仪(ICP-MS)技术分析了长期绿肥翻压对小麦籽粒矿质元素的影响。结果表明,绿肥处理下小麦籽粒大部分矿质元素含量较不施肥处理有增加趋势,其中硅、铁和铷元素含量均较不施肥和化肥处理显著增加;绿肥处理下籽粒重金属元素与不施肥处理无显著性差异,但镍含量较化肥处理表现增加。因而,长期绿肥翻压能有效提高旱地小麦部分矿质营养元素,有利于在保障小麦高产的同时提高籽粒营养品质,但也应关注绿肥翻压对重金属元素在土壤-作物系统中行为的影响。     

Relationship between oxide-ion conductivity and dielectric relaxation in the Ln2Zr2O7 system having pyrochore-type compositions (Ln=Yb, Y, Gd, Eu, Sm, Nd, La)

Ln₂Zr₂O₇ (Ln=Yb, Y, Gd, Eu, Sm, Nd, La) system changed from fluorite (F)-type to pyrochlore (P)-type phases when the ionic radius ratios, r(Ln³⁺)/r(Zr⁴⁺), were larger than 1.26. The oxide-ion conductivity showed sharp maximum at the vicinity of the phase boundary between the F- and P-type phases. The frequency dependence of dielectric constant () and dielectric loss factor () were successfully explained by the superimposition of Debye-type polarization due to dopant-vacancy associate and electrode-electrolyte interfacial polarization by the numerical calculation. The peak of dielectric loss tangent (tan δ) was ascribed to the dopant-vacancy associate. The ε_r(0) and dielectric constant of the associate (ε_r0) showed also the maximum values at the vicinity of the phase boundary between the F- and P-type phases.     

The effect of the linear charge density of carrageenan on the ion binding investigated by differential scanning calorimetry, dc conductivity, and kHz dielectric relaxation

The effect of the linear charge density of natural polyelectrolyte, carrageenan, on the ion binding to carrageenan molecules in relation to the gelation was investigated by using the dielectric relaxation spectroscopy, dc conductivity, optical rotation, and differential scanning calorimetry (DSC). Although carrageenan is an anionic polysaccharide, carrageenan molecules in the helix state at low temperatures can bind not only cation, such as potassium and cesium, but also anion, such as iodide. The dc conductivity steeply decreases just below the coil–helix transition temperature, which indicates the binding of ion to the carrageenan molecules in the helix state due to the increase of the linear charge density compared with that in the coil state. The addition of NaI promotes the helix formation, and prevents from aggregation of helices, which was suggested by the results of the dynamic shear modulus and the DSC, and resulted in an increase of the relaxation amplitude of the lowest frequency relaxation (kHz) attributed to the fluctuation of the tightly bound counter ions along the high charge density region (helix). It is concluded that binding of iodide induces (1) the increase in the amount of tightly bound counterions to carrageenan molecules and (2) the formation of non-aggregated helix.     

On-chip graphene oxide aptasensor for multiple protein detection

The versatility of an on-chip graphene oxide (GO) aptasensor was successfully confirmed by the detection of three different proteins, namely, thrombin (TB), prostate specific antigen (PSA), and hemagglutinin (HA), simply by changing the aptamers but with the sensor composition remaining the same. The results indicate that both DNA and RNA aptamers immobilized on the GO surface are sufficiently active to realize an on-chip aptasensor. Molecular selectivity and concentration dependence were investigated in relation to TB and PSA detection by using a dual, triple, and quintuple microchannel configuration. The multiple target detection of TB and PSA on a single chip was also demonstrated by using a 2 × 3 linear-array GO aptasensor. This work enables us to apply this sensor to the development of a multicomponent analysis system for a wide variety of targets by choosing appropriate aptamers.     

Atmospheric pressure laser desorption/ionization using a 6–7 µm‐band mid‐infrared tunable laser and liquid water matrix

Due to the characteristic absorption peaks in the IR region, various molecules can be used as a matrix for infrared matrix‐assisted laser desorption/ionization (IR‐MALDI). Especially in the 6–7 µm‐band IR region, solvents used as the mobile phase for liquid chromatography have absorption peaks that correspond to their functional groups, such as O–H, CO, and CH₃. Additionally, atmospheric pressure (AP) IR‐MALDI, which is applicable to liquid‐state samples, is a promising technique to directly analyze untreated samples. Herein we perform AP‐IR‐MALDI mass spectrometry of a peptide, angiotensin II, using a mid‐IR tunable laser with a tunable wavelength range of 5.50–10.00 µm and several different matrices. The wavelength dependences of the ion signal intensity of [M + H]⁺ of the peptide are measured using a conventional solid matrix, α‐cyano‐4‐hydroxycinnamic acid (CHCA) and a liquid matrix composed of CHCA and 3‐aminoquinoline. Other than the O–H stretching and bending vibration modes, the characteristic absorption peaks are useful for AP‐IR‐MALDI. Peptide ions are also observed from an aqueous solution of the peptide without an additional matrix, and the highest peak intensity of [M + H]⁺ is at 6.00 µm, which is somewhat shorter than the absorption peak wavelength of liquid water corresponding to the O–H bending vibration mode. Moreover, long‐lasting and stable ion signals are obtained from the aqueous solution. AP‐IR‐MALDI using a 6–7 µm‐band IR tunable laser and solvents as the matrix may provide a novel on‐line interface between liquid chromatography and mass spectrometry. Copyright © 2015 John Wiley & Sons, Ltd.     

Electron-phonon interaction and localization of surface-state carriers in a metallic monolayer

Temperature-dependent electron transport in a metallic surface superstructure, Si(111)sqrt[3] x sqrt[3]-Ag, was studied by a micro-four-point probe method and photoemission spectroscopy. The surface-state conductivity exhibits a sharp transition from metallic conduction to strong localization at approximately 150 K. The metallic regime is due to electron-phonon interaction while the localization seemingly originates from coherency of electron waves. Random potential variations, caused by Friedel oscillations of surface electrons around defects, likely induce strong carrier localization.     

Quenching and vibrational relaxation of SO(B3Sigma-, v' <or= 3) by collisions with Ar and N2

Fluorescence from a single vibronic level of SO(B3Sigma-, v' 相似文献   

Enhanced Cytotoxic Effects of Arenite in Combination with Active Bufadienolide Compounds against Human Glioblastoma Cell Line U-87

The cytotoxicity of a trivalent arsenic derivative (arsenite, As^III) combined with arenobufagin or gamabufotalin was evaluated in human U-87 glioblastoma cells. Synergistic cytotoxicity with upregulated intracellular arsenic levels was observed, when treated with As^III combined with arenobufagin instead of gamabufotalin. Apoptosis and the activation of caspase-9/-8/-3 were induced by As^III and further strengthened by arenobufagin. The magnitude of increase in the activities of caspase-9/-3 was much greater than that of caspase-8, suggesting that the intrinsic pathway played a much more important role in the apoptosis. An increase in the number of necrotic cells, enhanced LDH leakage, and intensified G₂/M phase arrest were observed. A remarkable increase in the expression level of γH2AX, a DNA damage marker, was induced by As^III+arenobufagin. Concomitantly, the activation of autophagy was observed, suggesting that autophagic cell death associated with DNA damage was partially attributed to the cytotoxicity of As^III+arenobufagin. Suppression of Notch signaling was confirmed in the combined regimen-treated cells, suggesting that inactivation of Jagged1/Notch signaling would probably contribute to the synergistic cytotoxic effect of As^III+arenobufagin. Given that both As^III and arenobufagin are capable of penetrating into the blood–brain barrier, our findings may provide fundamental insight into the clinical application of the combined regimen for glioblastoma.     

Perfectness of Conelike *–Semigroups in ℚk

Let S be an abelian *–semigroup in ℚ^k. We give a sufficient condition for every positive definite function on S to have a unique representing measure on the dual semigroup of S (i.e. S is perfect). To characterize perfectness for any abelian *–semigroupis a challenging, but not yet generally solved problem. In this paper, we characterize the structure of involutions on an abelian *–semigroup which is a subset of ℚ^k, and show that any conelike *–semigroups in ℚ^k are perfect.