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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.

Background: Techniques of MV repair have undergone many modifications and improvements in the last three decades, which have made it a more predictable and reproducible method either in rheumatic or degenerative mitral valve repair.Aim of Study: 1- Comparing the results of repairing degenerative mitral valve versus the rheumatic pathology. 2- Assessment the results of resectional technique (excising part of valve leaflet) and the respect one (preserving the valve leaflet without excision any part of it) for posterior leaflet prolapse during the degenerative mitral valve repair.Patients and Methods: This prospective study was con-ducted in the Department of Cardiac Surgery, National Heart Institute (NHI) from July 2014 to December 2017 including postoperative follow-up at 6 months. One hundred cases with severe mitral valve regurgitation underwent mitral valve repair divided into two groups: Group “D” where 50 cases had degenerative mitral valve pathology with a predominant mitral regurgitation and Group “R” where 50 cases had rheumatic valve disease with a predominant mitral regurgitation and high likelihood of repair. Techniques used for repair of prolapsed degenerative PML divided into resection technique and respect one.Results: As regards comparison between Group “D” versus Group “R” there was significant increase in MV area, MPAP and mean diastolic gradient of MV in group “D” than group “R” at 6 months of post-operative follow-up. Five cases in Group “R” had a mean diastolic mitral gradient more than 10mmHg that needed mitral valve replacement, four cases of them were post leaflets' shaving and decalcification. Degree of residual mitral regurgitation in Group “D” included 41 (82%) cases with no or trivial regurgitation while 9 (18%) cases were mild, whereas in group “R” 37 (74%) cases had no or trivial regurgitation, 9 (18%) had mild mitral regurgita-tion, 2 (4%) was mild to moderate and 2 (4%) cases had moderate mitral regurgitation that needed further follow-up with echocardiography every 6 months. Comparison between resection technique versus respect one revealed a significance difference between both groups as regards MVA and size of the ring annuloplasty but no significance difference was found between both groups as regards degree of residual MV regurgitation or mean diastolic MV gradient after 6 months of follow-up.Conclusions: The early postoperative results for posterior mitral leaflet repair with respect technique using Uniscalloping of posterior leaflet or artificial chordae-ePTFE-is very accept-able and recommended. Using of artificial chordae to AML is very effective and safe to solve the problem of leaflet prolapse. Rheumatic valve repair appears to be possible in selected cases with rheumatic mitral valve dysfunction. Leaflet procedures in rheumatic valve repair may be associated with reduced durability of rheumatic MV repair.

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.

Background Pharmacotherapy in the management of cardiovascular disease patients with multiple co-morbidities has been challenging due to polypharmacy (five or more drugs). They have been attributed with potential drug – drug interactions (DDI). Detecting the clinically significant drug interactions allows the opportunity for prevention through clinical drug decision support system (CDDSS) and clinical management. Purpose To identify significant potential DDI in critical cardiac patients Method We prospectively observed patients admitted at CCCU received multiple medications leading to potential DDI from Feb 2018 to July 2018 using two commercially available CDDSS along clinical management and pharmacovigilance algorithm. Results Patients admitted at CCCU co-administered with two or more drugs were analyzed. The mean age was 61.1 years. Total 649 patients were screened, resulting 87.7% (569/649) patients took more than five drugs. Of the 4249 potential DDI 543 were unique interacting drug pairs. On average, CCU patients were prescribed with 12.1 drugs, potentiating 14.1 potential DDI. Older patients (>60 years) received more medications than younger ones (mean 18.7 vs 15.1 drugs). 82.1% patients had one or more potential DDI with major and moderate severity detected by one or both CDDSS. Common potential clinical adverse was bleeding, QTc prolongation and CYP3A4 inhibition. Both CDDSS agreed on the severity ratings in 36.9%. There were significant association of potential DDI with specific risk factors (geriatric, female, Indian and heart failure patients) Conclusions Rate of potential DDI adversely influenced by polypharmacy, antiarrhythmic drugs, comorbidities and LOS. Significant potential DDI occur in the CCU, highlighting the need for CDDSS potentially prevent patient harm. Identified risk factors (geriatrics population, female sex, Indian ethnicity and heart failure patients) can be used in mitigating adverse DDI. Funding Acknowledgement Type of funding source: Private hospital(s). Main funding source(s): NATIONAL HEART INSTITUTE

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.

This study uses the stir-casting technique to combine a semi-solid AA2024 alloy directly with finely-sized β-SiCp embedded as a powder or with mechanically alloyed granules as a delivery agent. Liquid-state primary fabrication tends to form agglomerates of reinforcement particles, whereas rolling better distributes the composite constituents. Sub-micron reinforcements of low volume fractions do not significantly increase the hardness of the composite materials. Uniaxial tensile testing at elevated temperatures over a wide range of strain rates showed simultaneous increases in the ductility and crack resistance of AA2024 + SiCp granules embedded as a powder when compared to the non-reinforced control material at lower strain rates, with the same toughness as the control material. The maximum engineering strain of 252.7 ± 19.2% was observed in AA2024/SiCp at a strain rate of 10−4 s−1. This improvement in properties is attributed to grain refinement in the MMCs, leading to pinning events during the straining and ductility increases. The resultant impediments to grain growth and crack propagation allow the fine-sized reinforcements to control dynamic microstructural changes during fatigue. Cube {001} is a dominant texture component in AA2024, whereas the Goss {011} and S {123} components mainly represent the texture of the discontinuously reinforced aluminum matrix.

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.

To investigate the role of tonoplast Na+/H+ antiporters (ZmNHX) in salt-stress resistance newly developed maize (Zea mays L.) SR hybrids and cv. Across 8023 were tested under low (50 mM NaCl) and high salinity (200 mM NaCl). Resistance to Na+ toxicity was monitored in terms of shoot growth and number of necrotic leaf spots. At high salinity, the SR hybrids showed better shoot growth than Across 8023. SR 03 and SR 05 had a lower number of necrotic spots per leaf compared to SR 20 and Across 8023. Based on these results, SR 03 and SR 05 were classified as salt-resistant, and SR 20 and Across 8023 as salt-sensitive genotypes. At 200 mM NaCl, the salt-resistant hybrids SR 03 and SR 05 showed a significant upregulation of the tonoplast Na+/H+ antiporter (ZmNHX) in leaves compared with Across 8023 and SR 20. The salt stress–induced increase in transcription of ZmNHX may lead to enhanced tonoplast Na+/H+ antiport in leaves for SR 03 and SR 05. Hence, sequestration of Na+ into leaf vacuoles contributes to salt resistance of these genotypes by protecting the cytoplasm from Na+ toxicity. Relative transcription of ZmNHX in roots was only increased in SR 20, which may explain the efficient Na+ exclusion from shoots of SR 20.

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.

Since the beginning of the Mars planet exploration, the characterization of carbon dioxide hypersonic flows to simulate a spaceship’s Mars atmosphere entry conditions has been an important issue. We have developed a Tunable Diode Laser Absorption Spectrometer with a new room-temperature operating antimony-based distributed feedback laser (DFB) diode laser to characterize the velocity, the temperature and the density of such flows. This instrument has been tested during two measurement campaigns in a free piston tunnel cold hypersonic facility and in a high enthalpy arc jet wind tunnel. These tests also demonstrate the feasibility of mid-infrared fiber optics coupling of the spectrometer to a wind tunnel for integrated or local flow characterization with an optical probe placed in the flow.

The investigation of electrical energy management (EEM) in the industrial and commercial sector determines how energy management affects elec-tricity consumption and what makes its potential for being used to reduce peak demand of utility indus-tries. The aim of this paper is to analyze the contri-bution of electrical energy management in the industrial and commercial sector and highlight its challenges to the Tanzanian utility industry. Energy efficiency technology analyzed in this paper includes energy efficiency lighting and power factor improvement. The analysis found that, if EEM is properly implemented, a significant amount of energy could be saved and could be converted to monetary benefits which might facilitate the devel-opment of other activities. The utility industry can benefit from saving considerable amounts of energy as well as the reduction of peak demand which can minimize the race of stumbling on new energy sources and construction of new power plants. The saved energy can be distributed to other consumers so as to improve accessibility or reliability of the electrical system and consequently minimize the impact of environmental pollution.

A framework from multiple theoretical perspectives was developed to examine the link between a set of organizational and group variables and the level of group innovation. Survey data were collected from a sample of 150 government divisions in the United Arab Emirates, representing various functional areas, and analyzed using multivariate methods. Results indicate that managerial attitude, decentralization, supervisory support, group satisfaction, diversity, committee membership, and management learning are significant predictors of group innovation. Implications of the results are discussed and suggestions for future research presented.

Intracavity frequency doubling of a pulsed Ti:sapphire laser is shown to be well described by multimode rate equations nonlinearly coupled through the homogeneous gain linewidth of the amplifying medium. Hole burning in the fundamental wave spectrum is observed at the phase-matched frequency and is explained well by theory in terms of the dynamic depletion of the fundamental waves phase-matched to the nonlinear output mirror. The doubling conversion efficiency is shown to be greatly improved by injection seeding at the same frequency as the "spectral hole" with a low power continuous-wave-tunable laser diode. This leads, for the first time to our knowledge, to single-mode UV-tunable (380-410 nm) emission using this technique. Finally, the source is shown to exhibit a minimum yield at the coincidence between injection and exactly phase-matched wavelengths while maintaining high efficiency when injecting a few nanometers away from the phase-matching maximum.

A new pseudospark-type electron gun has been utilized in the F4 high-enthalpy, low-density, hot-shot wind tunnel at ONERA. The main goal was to perform accurate measurements of the velocity profile across the boundary layer and the freestream through a time-of-flight principle. In these experiments, an intense pulsed electron beam traces the path of a high-voltage, sustained-glow discharge in some 10 ns. A charge-coupled device camera is opened briefly, 5 μs after the electron gun actuation, to image the position of the luminous column convected by the flow

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.

A prototype based on the Electron Beam Fluorescence (EBF) Technique is being developed for in-flight measurements in the shock layer of a reentry demonstrator. The measurement objectives are rotational and vibrational temperatures of N2 as well as the densities of N2 and NO at different positions in and outside a shock layer. There is a renewal of interest in extending the technique to higher densities and to probe CO/CO2 flows (Mars atmosphere studies). The present paper gives a brief description of the status of the instrument with details on the optimization work performed to miniaturize the electron gun, the study of induced fluorescence in some gases and mixtures in laboratory vacuum chamber.

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

We report on a novel 2 μm laser transmitter for CO 2 DIAL, based on a nanosecond parametric master oscillator-power amplifier architecture. The master oscillator is an entangled-cavity, doubly resonant, optical parametric oscillator, based on a type-II periodically poled Lithium Niobate nonlinear crystal. This device provides single-longitudinal-mode radiation, with a high frequency stability and high beam quality, with no need of an additional seeding source. The 2.05 μm signal emission is amplified by multi-stage parametric amplifiers to generate more than 10 mJ. After amplification, both the spectral purity and beam quality are maintained: we demonstrate single-longitudinal-mode emission with a frequency stability better than 3 MHz rms, within a nearly diffraction limited beam, with a M 2 quality factor close to 1.5. The unique performances of this parametric architecture make this device a relevant transmitter for CO 2 differential-absorption LIDAR. Such approach could be readily duplicated for the detection of other greenhouse gases.

Cavity ringdown spectroscopy is an efficient gas-sensing method, but improvement in measurement speed is required before this method can be applied to the analysis of fast phenomena. We present a new continuous-wave cavity ringdown design, involving fast tuning of the laser frequency and a rapidly swept optical cavity, to allow high-speed sensing with spectral resolution refinement. This approach, which provides a simple and versatile instrument, is investigated numerically and experimentally. By performing detection of a forbidden transition of molecular oxygen near 766 nm during a 2-ms single sweep of the laser frequency, we show that our system fulfils the requirements for probing rapid chemical processes.

Recently, laser specifications for a spaceborne sensitive measurement of CO 2 , by differential absorption LIDAR (DIAL) at 2.05 µm, have been derived in terms of output energy, frequency stability and beam quality [1]. In particular, the laser transmitter frequency should be stabilized a few GHz away from the centre of the R30 CO 2 line, with a stability around 2 MHz rms, at tens of mJ of energy levels, within a diffraction limited beam.

For CO2 DIAL, the single mode output of a type II PPLN, entangled-cavity nanosecond OPO is amplified to 11 mJ at 2.05 µm, with 3MHz frequency stability and a M2quality factor better than 1.9.

For CO 2 differential-absorption LIDAR, the single-mode output of a type-II PPLN entangled-cavity nanosecond doubly-resonant OPO emitting at 2.05 µm is amplified to 11 mJ, with 3 MHz rms frequency stability and a M2 ≪ 1.9.

We present two long-path absorption systems, one based on cavity ring down and another on a Herriott cell, both with a re-entrant configuration to enhance spectral resolution and setup easiness, to measure weak absorption coefficients.

In the framework of a European research project, ONERA and DLR have studied the applicability of infrared laser techniques to gas turbine combustor measurements. The final goal is to replace gas analysis with probe measurements by optical techniques fulfilling the ICAO standards for engine emission measurements. Infrared laser absorption spectroscopy has the potential for fast, high spatial resolution measurements of combustion species with rugged equipment and therefore might contribute to the reduction of combustor development time and cost. Furthermore, the measurement of minor species in the combustor could help the understanding of the combustion process in the gas turbine. The tunable diode laser absorption technique of ONERA was used to probe CO, CO2, NO and H2O. The apparatus and measurement procedure including the upgrades for the combustor measurements are described. Successful measurements were achieved with CO inside and outside of the combustor. The reactive flow field of the model combustor was characterized with conventional measurement techniques. The CO measurements by TDLAS were compared with probe measurements that could be weighted by temperature and velocity measurements. Furthermore, temperature information was derived from the Laser measurements. The results are compared and further improvements are discussed.

We present what we believe to be the first intracavity tripled Ti:sapphire laser. This source is tunable in the 275-285-nm range and will be useful for applications in the detection of important atmospheric species such as OH and NO radicals. Single-frequency operation and high optical yield (>50%) are obtained in this system after it has been injected by a laser diode.

Non-intrusive optical sensing tools are needed to monitor trace molecular oxygen (O/sub 2/) in reactive flows generated in blow-down wind tunnels. Continuous-wave cavity ringdown spectroscopy (cw-CRDS) is a promising candidate to perform such analysis. However, those measurements impose strong constraints since flow generation is realized during short gusts (200 ms), characterized by low pressures and aerodynamic conditions changing rapidly. The crucial issue therefore consists in developing CRDS as a fast and high-resolution diagnostic method.