Pecan (Carya illinoinensis) is sensitive to Zn, which is involved in basic physiological and biochemical processes.
To explore the growth and physiology of pecan in response to Zn application, we ...used 1‐year‐old annual grafted seedlings (Pawnee) and applied four concentrations of Zn fertilizer (0.05, 0.10, 0.20 and 0.40 g·plant−1); a control (CK; no Zn fertilization) was also included. The growth characteristics, anatomical structure of the leaves and photosynthesis were assessed.
Compared with the CK, photosynthesis and chlorophyll (Chl) fluorescence parameters, leaf area and leaf structure significantly increased at Zn concentrations of 0.05 and 0.10 g·plant−1. In addition, growth of pecan at the seedling stage increased in response to moderate Zn application. In contrast, treatment with 0.20 and 0.40 g·Zn·plant−1 dramatically decreased these physiological indices and inhibited pecan growth.
The results show that moderate soil Zn application promotes pecan growth and development by increasing photosynthesis. However excess Zn concentrations were not conducive to seedling growth. The concentration of 0.1 g·Zn·plant−1 was best when considering long‐term soil Zn applications, providing a theoretical foundation for microelement management of pecan.
Moderate Zn application promoted the growth and development of pecan by improving photosynthesis‐related physiological mechanisms.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
Aims
To purify and characterize the biosurfactants produced by Achromobacter sp. HZ01.
Methods and Results
After fermentation, one biosurfactant was successfully purified from the fermentation broth ...of strain HZ01 by centrifugation, extraction using ethyl acetate, silica gel chromatography and reversed phase–high performance liquid chromatography. The critical micelle concentration (CMC) of the biosurfactant and the effects of temperatures, pH and salinities on its stability were determined. Fourier transform infrared spectroscopy, analysis of fatty acids and amino acids and mass spectrometry were used to characterize the biosurfactant. The maximum production yield of the crude biosurfactant reached to 6·84 g l−1 after incubation for 96 h. Except the favourable adaptability to a wide range of temperatures, pH and salinities, the biosurfactant with a CMC value of 48 mg l−1 could efficiently emulsify diverse hydrophobic compounds. The chemical formula of this biosurfactant was confirmed to be CH3‐(CH2)17‐CHO‐CH2‐CO‐Gly‐Gly‐Leu‐Met‐Leu‐Leu, in which the oxygen atom of group CHO linked to the last amino acid (Leu), a structure had never been reported before.
Conclusions
The purified biosurfactant is a novel cyclic lipopeptide.
Significance and Impact of the Study
One novel lipopeptide was purified and characterized. The novel biosurfactant exhibited good potential applications, such as bioremediation.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
Non-shearable metal carbide (MC) nanoparticles are one of the most effective strengthening media for improving creep resistance of alloys at elevated temperatures. However, it is difficult to achieve ...sufficient homogeneous dispersion due to their large crystallographic difference with the matrix. Herein, we report a feasible method to form massive NbC nanoprecipitation in an aluminum-forming stainless steel via the combination of microalloying and pre-straining. The employment of pre-straining generated dislocations uniformly distributed inside the alloy matrix, which provides high-density heterogeneous nucleation sites and enables fast pipe diffusion channels for involved solutes, thus substantially enhancing the nucleation rate of the secondary NbC. Moreover, due to its stronger affinity with C and larger diffusivity as compared with Nb, Ti atoms were found to occupy the Nb sublattice of the NbC at the onset of precipitation. The formation of (Ti,Nb)C nuclei with decreased lattice misfit (from 20.8% to 19.1%) effectively reduced the critical nucleation energy barrier and thus enhanced the nucleation rate accordingly. With the synergistic effect of 0.1 wt% Ti microalloying and 10% pre-straining, massive precipitation of refined secondary (Ti,Nb)C nanosized particles (4.4 ± 0.7 nm) with a much increased volume fraction (almost 6.8%) was practically realized, remarkably reducing the steady-state creep rate and prolonging the creep-to-rupture lifetime to 2044 h at 1023 K and 120 MPa. The current findings provide a feasible strategy to disperse strong yet massive nanoparticles within metallic metrics, which may shed new insights into the development of advanced high-temperature alloys with much enhanced creep properties at no expense of oxidation resistance.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Core−shell Li3V2(PO4)3@C nanostructured composites were prepared via a sol−gel route followed by hydrothermal treatment. XRD patterns showed that Li3V2(PO4)3 has a monoclinic structure with space ...group P21/n. TEM images exhibited that Li3V2(PO4)3 particles are encapsulated with a carbon shell ∼10 nm in thickness. Compared with pure Li3V2(PO4)3, core−shell Li3V2(PO4)3@C composites presented enhanced electrochemical Li ion intercalation performances. Cyclic voltammetry and electrochemical impedance spectroscopy disclosed that carbon shells improved Li ion diffusion and electrical conductance significantly and also retarded formation of solid electrolyte interphase film of Li3V2(PO4)3 cathode materials.
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IJS, KILJ, NUK, PNG, UL, UM
Aim To determine the features of caesarean scar ectopic pregnancy (CSP) by using magnetic resonance imaging (MRI) in the first trimester. Materials and methods Thirty-nine women with CSP in the first ...trimester were initially selected and underwent transvaginal ultrasound and MRI examinations. Thirty-five patients with CSP were finally included in this study. Results The CSPs were categorized into three groups: type I, in which a thin-walled diverticulum is present at the caesarean section scar (CSS) defect and the gestational sac (GS) is embedded in the diverticulum; type II, in which a thin-walled diverticulum is present at the CSS defect and the GS is partially embedded in the diverticulum; type III, in which a niche is present in the CSS defect and the GS is mainly embedded in the isthmus. Types I, II, and III CSP occurred in 40, 46, and 14% of the women, respectively. There was no significant difference between the three types in the minimum thickness of the CSS defect. In types I and II, there was a positive correlation in the maximum inlet diameter of the CSS defect and the approximate area of the GS. Conclusion Using MRI, most CSPs present as a diverticulum at the CSS defect, and the CSS defect becomes weaker with the growth of the GS. MRI showed detailed features of the CSP.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
The aim of this study was to characterize detailed interfacial microstructures and evaluate tensile properties of Al6061-to-Cu dissimilar welded joints via electromagnetic pulse welding (EMPW) at ...different discharge voltages. The EMPWed joints consisted of annular weld zone and central non-weld zone. The outer and inner regions of annular weld zone exhibited mainly diffusion bonding and mechanical interlocking, respectively, representing a well-bonded interface. Distinctive discontinuous “droplet-like” pseudo-eutectic (α-Al + Al2Cu) particles or patches were observed to eject in the adjacent transition region in the non-weld zone. The highly non-equilibrium eutectic-like liquid or slurry at the Al/Cu interface was formed due to the ultra-high strain rate experienced by the interface and the ensuing instant temperature rise beyond the eutectic temperature of Al–Cu system, when the high-velocity flyer Al sheet crashed into the fixed Cu sheet driven by the Lorentz force during EMPW. The interfacial diffusion layer was thin in the order of 1–2 μm. The higher the discharge voltage was, the more obvious the interfacial diffusion layer and mechanical interlocking were, with “wave-like” and “inverted hook-like” interfacial characteristics observed. While interfacial failure occurred during the tensile lap shear tests for the joints made at a discharge voltage of 12 kV, the failure loads were still significantly higher than those specified in the AWS D17.2 standard. The EMPWed joints made at 14 kV and 16 kV remained intact and only base metal failure occurred, with the tensile lap shear failure loads reaching over twice those specified in the AWS D17.2 standard. Thus the well-bonded robust Al/Cu dissimilar welds were successfully achieved via EMPW.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
The excellent electroluminescent (EL) properties of 1,1-disubstituted 2,3,4,5-tetraphenylsiloles, 1-methyl-1,2,3,4,5-pentaphenylsilole (MPPS), and 1,1,2,3,4,5-hexaphenylsilole (HPS) have been found. ...Despite some studies devoted to these materials, very little is known about the real origin of their unique EL properties. Therefore, we investigated the structures, photoluminescence (PL), and charge carrier transport properties of 1,1-disubstituted 2,3,4,5-tetraphenylsiloles as well as the effect of substituents on these characteristics. The single crystals of the three siloles involving 1,1-dimethyl-2,3,4,5-tetraphenylsilole (DMTPS), MPPS, and HPS were grown and their crystal structures were determined by X-ray diffraction. Three siloles have nonplanar molecular structures. The substituents at 1,1-positions enhance the steric hindrance and have predominant influence on the twisted degree of phenyl groups at ring carbons. This nonplanar structure reduces the intermolecular interaction and the likelihood of excimer formation, and increases PL efficiency in the solid state. The silole films show high fluorescence quantum yields (75−85%), whereas their dilute solutions exhibit a faint emission. The electronic structures of the three siloles were investigated using quantum chemical calculations. The highest occupied molecular orbitals (HOMOs) and the lowest unoccupied molecular orbitals (LUMOs) are mainly localized on the silole ring and two phenyl groups at 2,5-positions in all cases, while the LUMOs have a significant orbital density at two exocyclic Si−C bonds. The extremely theoretical studies of luminescent properties were carried out. We calculated the nonradiative decay rate of the first excited state as well as the radiative one. It is found that the faint emission of DMTPS in solutions mainly results from the huge nonradiative decay rate. In solid states, molecular packing can remarkably restrict the intramolecular rotation of the peripheral side phenyl ring, which has a large contribution to the nonradiative transition process. This explains why the 1,1-disubstituted 2,3,4,5-tetraphenylsiloles in the thin films exhibit high fluorescence quantum yields. The charge carrier mobilities of the MPPS and HPS films were measured using a transient EL technique. We obtained a mobility of 2.1 × 10-6 cm2/V·s in the MPPS film at an electric field of 1.2 × 106 V/cm. This mobility is comparable to that of Alq3, which is one of the most extensively used electron transport materials in organic light-emitting diodes (LEDs), at the same electric field. The electron mobility of the HPS film is about ∼1.5 times higher than that of the MPPS film. To the best of our knowledge, this kind of material is one of the most excellent emissive materials that possess both high charge carrier mobility and high PL efficiency in the solid states simultaneously. The excellent EL performances of MPPS and HPS are presumably ascribed to these characteristics.
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IJS, KILJ, NUK, PNG, UL, UM
Fretting wear tests of Inconel 690 alloy have been carried out at various temperatures (room temperature – RT, 90°C, 200°C and 285°C) for tube/plate contact configuration. The worn surfaces and ...cross-sectional morphologies were observed through scanning electron microscopy (SEM), energy dispersive X-ray (EDX) and electron probe microanalysis (EPMA). Moreover, a particular debris cleaning method was used to remove wear particles of worn Inconel 690 alloy effectively in order to estimate exact wear volume. Overall, the results indicated that temperature had a great impact on fretting wear behavior and wear mechanisms. With increase in temperature, the principal wear mechanisms changed from delamination wear to the combination of delamination and adhesive wear, as demonstrated by the presence of an adhesive transfer layer at 285°C, instead of a compacted debris bed at 90°C. The adhesive transfer layer seemed to protect the surfaces better due to a reduction in the interaction of the worn surfaces. Finally, higher friction coefficient and wear volume appeared at lower temperature (RT to 90°C), compared to that associated with higher temperature (200°C and 285°C).
•A chemistry cleaning method was used to remove the wear particles.•A model was proposed to describe wear mechanisms and temperature.•Adhesive wear played a significant role in wear above 200°C.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
This study aims to clarify the notch factor effect on the mechanical properties of carbon steel plates and the strain field distribution at the notch during the tensile process. To this end, tensile ...tests were conducted on 20, 45, and 60 steel notched plates of different sizes at 4 mm/min tensile speed, and the Johnson–Cook intrinsic structure model was used to calibrate the true stress–true strain relationship. The nodal strain and surface strain field distribution at notches were determined based on the digital image correlation (DIC) method, and the tensile process of 45 steel plates was simulated by Abaqus finite element method based on Johnson–Cook model to verify its accuracy. The deformation results of the three materials conformed to the Johnson–Cook model stress-strain law; the notch sensitivity of the materials increased and then decreased with the notch size, reaching the maximum at
ρ
=
0.2 mm. The DIC method results agreed well with the simulated strains, mainly concentrated near the root of the notch in the
x
- and
y
-axis directions. The strains in the
xy
-plane direction are roughly symmetrically distributed in a 45° shear shape and mainly concentrated at the edge of the notch.
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DOBA, EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, IZUM, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UILJ, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
Objective:
To investigate the therapeutic effect and mechanism of sodium tanshinone IIA sulfate (STS) on paraquat (PQ)-induced myocardial injuries in a rat model.
Methods:
Healthy adult Sprague ...Dawley rats were randomly divided into normal control, PQ, and PQ + STS groups. PQ group was given a single intragastric administration of PQ (80 mg/kg). PQ + STS group was intraperitoneally injected with STS (1 ml/kg) at 30 min following PQ exposure. Rats in control and PQ groups were injected with equal amount of saline. After 12, 24, 48, and 72 h, rats were killed, and the apoptosis of myocardial cells was detected. Myocardial expression of Bax and Bcl-2 was measured. The activity of the nuclear erythroid 2-related factor 2 (Nrf2) pathway was assessed by Western blot.
Results:
The apoptotic cells in PQ group were significantly increased in a time-dependent manner compared with the control group (p < 0.01). The rats in PQ group exhibited significantly lower Bcl-2 expression, but notably higher Bax expression at 12, 24, 48, and 72 h after PQ exposure (p < 0.05 or 0.01). STS intervention markedly reduced the proportion of apoptotic myocardial cells, increased Bcl-2 expression, and decreased Bax expression at 24, 48, and 72 h after treatment (p < 0.05 or 0.01). The expression of phosphorylated Nrf2 and heme oxygenase 1 in PQ + STS group was significantly increased compared with PQ and control groups (p < 0.05 or 0.01).
Conclusion:
STS effectively inhibits PQ-induced myocardial cell apoptosis in rats via modulating the Nrf2 pathway, suggesting its potential as a promising therapeutic agent for PQ-induced myocardium damage.
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