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Potassium (K) being the major limiting factor affecting cotton yield and quality has received massive research attention and the effects of various K fertilization techniques/organic amendments have been studied extensively. However, it is not clear whether the straw based, high pH biochar affects K availability, lint yield and quality of the cotton crop in alkaline calcareous soils. In the present study, we carried out a field experiment on a moderate to strongly calcareous silt loam soil to demonstrate the effect of straw-based biochar and potassium application levels on the growth, seed cotton yield and the lint quality. The experimental treatments comprised of two factors, A) biochar types i) Control no biochar, ii) Rice husk biochar (RHB), iii) Wheat straw biochar (WSB), and iv) Rice straw biochar (RSB), factor B) potassium application levels (i) control, no K fertilizer application, ii) K at 15 kg ha−1, and iii) K at 30 kg ha−1 (4 × 3 × 3, n = 36). Results showed that overall cotton growth and yield was significantly improved with increasing rates of potassium application. Three biochar sources affected seed cotton yield and quality with varying effects. For instance, the RSB increased plant height (11.71% to 22.47%), number of bolls per plant (0.74% to 13.75%), average boll weight (35.44% to 36.22%), the seed cotton yield was increased by 14.48% over the control when rice straw biochar was applied in combination with potassium at 30 kg ha−1. However, the ginning out turn (%) was declined with potassium application in combination with all three-biochar compared to control (no biochar addition). The WSB increased staple length and micronaire by 4.32% and 24.50% without potassium application. The potential effects of straw based biochar and potassium application on seed cotton yield and quality deserve further studies to identify the most suitable biochar as per soil chemical properties.

This review article is devoted to studies of the structure and properties of Fe–Ga alloys that serve as functional materials with high magnetostriction. Particular attention is paid to diffraction methods that allow one both to monitor phase transformations in real time and identify phase structures and microheterogeneities in their structure. Based on the studies published in recent decades, the existing equilibrium diagrams and mechanisms of formation of elastic and anelastic properties, including magnetostriction and internal friction, are critically analyzed.

A significant difference in properties and structure of Fe-Ga alloys in their equilibrium and metastable states limits their application. This necessitates an immediate understanding of the importance of cooling rate in the formation of alloy metastable and equilibrium structures. In this paper, we experimentally studied the structure of the Fe-(23−24) Ga alloys after both (i) cooling with different cooling rates and (ii) isothermal annealing between 300 and 575 °C up to 1800 h to report the alloy structure and present the Time-Temperature-Transformation (TTT) diagrams for the metastable to equilibrium transition in these alloys. The critical cooling rates were defined with respect to the formation of the equilibrium state. A theoretical model along with corresponding Monte Carlo simulations for modeling phase transitions and construction of TTT diagram for the same alloys were developed: simulated phase diagrams were analyzed with respect to our the experimental findings.

Anelastic effects in Fe-(23–38)Ga binary and ternary alloys doped with rare-earth (RE) elements, RE = Pr, Sm, Tb, Er, and Yb, are studied in a sub-resonance frequency through heating and cooling in the range from 0 to 600 °C. In situ neutron diffraction, vibrating sample magnetometry (VSM), and differential scanning calorimetry (DSC) are used to trace phase transitions during heating and cooling and to interpret anelastic effects due to phase transitions. Besides the thermally activated effects, two transient effects due to the first-order transitions D03 → L12 and B2/D03 → Fe13Ga9 (later in alloys with Ga content>29 at%) are studied. In most cases, the RE elements decrease the rate of phase transitions. The obtained results demonstrate an excellent correlation between temperature-dependent internal friction, in situ neutron diffraction, and vibrating sample magnetometry tests.

The present research was done to study the ability of cyanobacterial species for removing heavy metals from sewage. As well, to estimate the growth and some metabolites of Beta vulgaris irrigated w...

The present study investigated the influence of seed priming with silver nanoparticles (Ag NPs), 0, 2, 5 and 10 mM, on growth and biochemical parameters of wheat (Triticum aestivum L.) under salt stress. As expected, 150 mM of NaCl decreased the shoot fresh and dry weights and chlorophyll contents and increased the catalase (CAT) and peroxidase (POD) activities. Salinity enhanced the concentration of proline, soluble sugars, malondialdehyde and hydrogen peroxide. Seed priming with Ag NPs increased the shoot fresh and dry weight of normal and salt-stressed plants. Lower concentration of Ag NPs decreased the total soluble sugars and proline contents, while the higher Ag NPs levels increased these contents compared to the control. The combined application of Ag NPs and salt stress increased the soluble sugars and proline contents, while it decreased CAT activity and increased POD activity compared to the respective Ag NPs treatments alone. Overall, our results demonstrated that Ag NPs enhanced the sa...

Anelasticity of Fe-(16−21)at% Ga-RE (rare earth RE = La, Tb, Dy, Er, Yb elements) alloys at room and elevated temperatures is studied in a sub-resonance mechanical spectroscopy. Two thermally-activated and two transient effects are recorded in most of the studied alloys. To explain these phenomena, structure and phase transitions in several binary and ternary Fe-Ga alloys are investigated. The D03 ordering of rapidly cooled alloys with the A2 structure at heating at around 300 °C and the disordering at heating and the D03 ordering at cooling around 500 °C for annealed samples are proved using three in situ techniques: neutron diffraction, vibrating sample magnetometry, and internal friction and supported by positron annihilation experiments. Thermally activated transitory effects are tentatively explained by stress-induced reorientation of Ga-Ga, vacancy-vacancy pairs, and carbon atoms jumps.

The atomic structure of the high-temperature β-Fe6Ga5 phase, formed in the Fe-45at.%Ga alloy during rapid cooling from the melt, has been refined by X-ray, neutron diffraction techniques, and density functional theory calculations. The regularities of the phase composition evolution of the quenched Fe-45at.%Ga alloy in the process of continuous slow heating and cooling under vacuum conditions have been revealed. It is shown that after the heating-cooling cycle, the structures of the outer layers and the sample volume are completely different.

A pot experiment was conducted to investigate the interactive effect of salinity (125 mM) and varying concentrations of boron (B) (2, 4 and 6 mM) on the growth and biochemical attributes of wheat. Results showed that application of 4 and 6 mM B along with 125 mM NaCl significantly declined plant biomass and leaf length. The concentration of B in plant leaves was significantly lower in treatments where salinity and B were applied together as compared to individual applications of 2, 4 and 6 mM B. The membrane permeability and protein concentration were significantly increased by the combined application of NaCl and B, whereas the chlorophyll pigments were not influenced. The phenolic compounds and ascorbic acid concentrations were reduced with the individual applied 6 mM B and when combined with application of 125 mM NaCl + 6 mM B. The concentration of Milondialdehyde (MDA) gradually increased by increasing B application and maximum was at the highest level of B and NaCl stress. It is concluded that salinity worsens the deteriorating effect of boron toxicity on wheat growth. © 2016 Friends Science Publishers

The microstructures and phase compositions of Fe–Ga alloys with Ga contents from 15 to 45 at.% are investigated in detail applying prolonged annealing treatments at temperatures below 600 °C. X-ray diffraction (XRD), transmission electron microscopy (TEM), vibrating-sample magnetometry (VSM), and Electron backscatter diffraction (EBSD) coupled with scanning electron microscopy (SEM) methods were used in this investigation. The results are compared with predictions of four existing Fe–Ga phase diagrams proposed by W. Koster et al. (1977), J. Bras et al. (1977), O. Kubaschewski (1982), and H. Okamoto (1993). Several important inconsistencies are found and required corrections of the positions of three equilibrium boundaries. Below 400 °C, an incomplete, if any, transition from a metastable (A2 or D03) to the equilibrium (L12) state is seen after annealing for 300 h. Alloys with 25.5–28.1%Ga annealed at 450–500 °C for 300 h exhibit only the equilibrium L12 phase. Annealing at 575 °C for 300 h leads to an incomplete transition, too, indicating that the highest transition rate occurs at 100–150 °C undercooling.

The structure of the Fe-(17.5–19.5)at.%Ga alloys in as-cast and nearly equilibrium states is studied using XRD, ND, and EBSD. In disagreement with the existing phase diagrams, the long-term isothermally annealed at 450–500 °C Fe-17.5%Ga alloy has a two-phase structure with two co-existing ferromagnetic phases: bcc-originated A2(D03) as a matrix and a fcc-originated A1(L12) needle-shaped precipitates. The phase transitions during cooling of 17.5 and 19.5%Ga alloys from the A2 range of the phase diagram with different cooling rates were used to plot, at least partly, Time-Temperature-Transformation (TTT) diagrams. The critical cooling rates for starting first- and second-order transitions are determined for the Fe-19.5%Ga alloy. The effect of long-term annealing on magnetostriction is reported.

The effect of a high magnetic field (25 T) on the D03 to L12 phase transformation in two Fe-Ga alloys with 24 and 27 at.% Ga during isothermal annealing at 475 °C is investigated using neutron diffraction and magnetization measurements techniques. It is proved that annealing in the magnetic field increases the amount of fcc – derived L12 phase in both samples. This effect is stronger in the Fe-27%Ga alloy as compared with the Fe-24%Ga alloy. The reasons for enhancing the D03 to L12 phase transition in the magnetic field are discussed. We suggest that the most significant increase in the transformation rate is related to a decrease in the energy barrier between the phases involved in the transformation process.

A huge difference between the structure and the properties of equilibrium and metastable Fe-Ga alloys along with an uncertain specification for their metastable state lead to an urgent necessity to understand the cooling rate role in the formation of the alloys’ structure. We studied the structure of Fe-27%Ga alloy after cooling, in situ during cooling with different cooling rates and after isothermal annealing up to 300 h between 300 and 575 °C to report the alloy structure and present, for the first time, the Time-Temperature-Transformation (TTT) diagram for the metastable bcc to equilibrium fcc transition in this alloy. The critical cooling rates are determined as the beginning and the end of the formation of equilibrium L12 phase.

A wide range of complementary research technique - XRD, SEM, TEM, MFM, HV, and low temperature heat capacity, in situ neutron diffraction, resistivity, vibrating sample magnetometry, internal friction, dilatometry, and differential scanning calorimetry - is applied to study structure and phase transitions at heating and cooling of two Fe–Ga functional alloys with 25 and 27 at.% Ga. Using high resolution neutron diffraction, it is unambiguously proven that the initial state of both as-cast samples at room temperature is the D03 phase which results from ordering of the high temperature A2 phase during cooling. Heating of as-cast samples and their subsequent cooling leads to a cascade of phase transitions which change the samples’ structural, mechanical and physical properties. These transitions and properties are discussed in the paper. Transition from metastable D03 to stable L12 phase at heating or isothermal annealing leads to significant changes in macro (grain size) and micro (ordering) structure, hardness and magnetic properties (magnetostriction, magnetization). According to our structural studies (ND, XRD), composition Fe-25.5 at.%Ga below ∼600 °C belongs to a single phase (L12) range of the equilibrium phase diagram, while in the Fe-26.9Ga alloy some amount of the D019 phase is also present.

A huge difference between the structure and the properties of equilibrium and metastable Fe–Ga alloys along with an uncertain specification for their metastable state lead to urgent necessity of understanding the cooling rate role in the formation of the alloys structure. We studied structure of Fe-(9-33 at.%)Ga alloys after cooling with different cooling rates (furnace, air, water, as cast) and report structure and dependencies of lattice parameter for A2 and D03 phases on Ga content in Fe–Ga alloys. The first and second critical cooling rates are determined as the beginning and the end of formation of equilibrium L12 phase.

Active optical sensing of the atmosphere through long distances from airborne or satellite platforms requires specific and demanding features for the necessary laser sources in terms of wavelength addressing and power level. Many molecules of atmospheric interest for nowadays urgent issues like climate change and contrails (CO 2 , CH 4 , H 2 O) have their best relevant detection features in the near and mid infrared spectral bands whereas most present days robust lasers have limited emission in the visible or near infrared at a few fixed wavelengths imposed by the laser media. Photonic solutions like DFG, OPO or Raman shift have to be employed to provide the necessary frequency conversion to cover the spectral fingerprints of molecules to be probed. This presentation will review some of the developments undertaken in our laboratory to provide attractive solutions using these schemes. One of promising solutions is a high energy transmitter around 2 µm based on frequency conversion in a nested cavity doubly resonant optical parametric oscillator (NesCOPO) followed by high energy parametric amplification (MOPA architecture) as depicted in Figure1. This scheme enables the generation of tunable single-frequency (< 60 MHz) high energy nanosecond pulses (tens of mJ) suitable for differential absorption lidar (DIAL) probing of the atmosphere (Figure 2). Development is also being carried out with picosecond/femtosecond frequency comb lasers to provide extended spectral coverage for more species and to enable detection schemes like Fourier transform spectroscopy with a dual comb. Ultra-sensitive trace level local probing on a balloon or airplane carrier is also being investigated through enhanced geometry for quartz-enhanced photoacoustic spectroscopy.

International audience; At the output of a high-finesse cavity a succession of Lissajous patterns may be observed as the cavity length is finely tuned inside a "degenerate region" around a reentrant spherical configuration. This behavior is ascribed to a small parasitic astigmatism of the cavity mirrors. Simple geometrical optics modeling confirms this hypothesis, and then a more realistic analysis using transverse Gaussian modes reveals that the Lissajous patterns correspond to an organization of the astigmatism-split modes into a finer substructure of degenerate modes relative to that of a reentrant spherical cavity. This provides a thorough understanding of the field patterns observed in the degenerate region, including an intriguing spatial symmetry of the patterns corresponding to opposite displacements with respect to a specific central cavity length. This investigation represents a generalization of the theory of reentrant spherical cavities to the astigmatic case.

13 pages; International audience; We present a new compact electron gun based on the secondary emission through ionic bombardment principle. The driving parameters to develop such a gun are to obtain a quite small electron gun for an in-flight instrument performing Electron Beam Fluorescence measurements (EBF) on board of a reentry vehicle in the upper atmosphere. These measurements are useful to characterize the gas flow around the vehicle in terms of gas chemical composition, temperatures and velocity of the flow which usually presents thermo-chemical non-equilibrium. Such an instrument can also be employed to characterize the upper atmosphere if placed on another carrier like a balloon. In ground facilities, it appears as a more practical tool to characterize flows in wind tunnel studies or as an alternative to complex electron guns in industrial processes requiring an electron beam. We describe in this paper the gun which has been developed as well as its different features which have been characterized in the laboratory