Source Diameter Research Articles

The impacts of lulls and peaks in effusion rate on lava flow propagation

Variable effusion rates have been observed during the eruption and emplacement of lava flows which can complicate lava flow predictability. Conventional wisdom suggests that effusion rates decrease exponentially with time, however, this broad trend may also be subject to short-timescale fluctuations. Flow obstructions, changes in source diameter, channel or pond overflow, and changes within the magma reservoir to name a few factors can increase or decrease local flow rates repeatedly during an active eruption and impact the behavior of the flow. Analog experiments are a useful tool for investigating the role of changing effusion rates on flow propagation because they allow reasonably precise control of conditions and detailed documentation of resulting flows. In this work, we address the effects of decreasing and increasing extrusion rates (Q) on flow propagation and four emplacement modes common to lava flows: resurfacing, marginal breakouts, inflation, and lava tubes. We conducted 30 experiments by injecting dyed PEG wax into a chilled bath (∼ 0 °C) on a flat slope. We divided the experiments into two pulsatory extrusion rate patterns, or conditions: stepwise decrease followed by increase in extrusion rate (lull) and stepwise increase then decrease in extrusion rate (peak). We tested a range of flow conditions spanning from flows for which strong crust was favored (low wax temperature; low extrusion rates) and those for which weak crust was favored (high wax temperature; high extrusion rates). We found that a lull in extrusion rates when a strong crust was present promoted flow expansion and thickening via limited resurfacing, localized marginal breakouts, inflation, possible tube formation, with lower rates of flow expansion after the lull. In contrast, a lull and weak crust promoted flow expansion via widespread marginal breakouts, with flow advance rebounding after the lull, and inhibited flow thickening via inflation. A peak in extrusion rates with a strong crust favored flow expansion via widespread marginal breakouts, with flow-advance deceleration after the peak, and possible thickening via inflation. Conversely, a peak in extrusion rate with weak crust promoted flow expansion via widespread marginal breakouts, with flow-advance deceleration after the peak, and inhibited flow thickening via resurfacing and inflation. Our results have implications for pahoehoe flow emplacement and have been used to assess the most appropriate parameters to be used in a probabilistic flow propagation model, MrLavaLoba. Plain Language SummaryVariable effusion rates have been observed during the eruption of lava flows which can complicate lava flow forecasts. In general, lava flow effusion rates decrease with time exponentially although there may be fluctuations in flow rate on short timescales. Flow rates can wax or wane for a variety of reasons, such as flow obstructions, changes in the shape of the erupting source, or the release of more magma from the subsurface. Experiments using materials that behave as lava, such as wax, can be used to investigate how changes in effusion rate and subsequent flow rate impact flow emplacement. In this work, we address the effects of temporary lulls and peaks in extrusion rates on flow propagation. We focus on four emplacement modes common to lava flows: resurfacing, marginal breakouts, inflation, and lava tubes. We conducted 30 experiments by injecting dyed wax into a chilled bath (∼ 0 °C) on a flat slope. We divided our experiments into two extrusion rate patterns, or conditions: a lull (temporary decrease in extrusion rate) and a peak (temporary increase in extrusion rate). We tested a range of flow conditions – from flows with strong crust to those with weak crust. We found that a lull in extrusion rates when a strong crust was present promoted flow thickening via limited resurfacing and inflation and flow expansion via localized marginal breakouts, possible tube formation, and lower rates of flow expansion after the lull. In contrast, a lull and weak crust promoted flow expansion via widespread marginal breakouts, and flow advance rebounds after the lull. A peak in extrusion rates with a strong crust favored flow expansion via widespread marginal breakouts and flow thickening via resurfacing and inflation, and flow-advance deceleration after the peak. Conversely, a peak in extrusion rate with weak crust favored flow expansion via widespread marginal breakouts, and resulted in flow-advance deceleration after the peak. These experiments can help us understand how pāhoehoe flows grow and thicken and the results can be used with numerical models to improve flow forecasts.

X-ray counterpart detection and γ-ray analysis of the supernova remnant G279.0+01.1 with eROSITA and Fermi-LAT

A thorough inspection of known Galactic supernova remnants (SNRs) along the Galactic plane with SRG/eROSITA yielded the detection of the X-ray counterpart of the SNR G279.0+01.1. The SNR is located just 1.5° above the Galactic plane. Its X-ray emission emerges as an incomplete, partial shell of ~3° angular extension. It is strongly correlated to the fragmented shell-type morphology of its radio continuum emission. The X-ray spatial morphology of the SNR seems to be linked to the presence of dust clouds in the surroundings. The majority of its X-ray emission is soft (exhibiting strong O, Ne, and Mg lines), and it occurs in a narrow range of energies between 0.3 and 1.5 keV. Above 2.0 keV the remnant remains undetected. The remnant’s X-ray spectrum is purely of a thermal nature. Constraining the X-ray absorption column to values which are consistent with optical extinction data from the remnant’s location favors nonequilibrium over equilibrium models. A nonequilibrium two-temperature plasma model of kT ~ 0.3 keV and kT ~ 0.6 keV, as well as an absorption column density of NH ~ 0.3 cm−2 describe the spectrum of the entire remnant well. Significant temperature variations across the remnant have been detected. Employing 14.5 yr of Fermi-LAT data, we carried out a comprehensive study of the extended giga-electronvolt source 4FGL J1000.0-5312e. By refining and properly modeling the giga-electronvolt excess originating from the location of the remnant, we conclude that the emission is likely related to the remnant itself rather than being colocated by chance. The remnant’s properties as determined by the X-ray spectra are consistent with the ~2.5 kpc distance estimates from the literature, which implies a source diameter of ~140 pc and an old age of >7 × 105 yr. However, if the source is associated with any of the pulsars previously considered to be associated with the SNR, then the updated nearby pulsar distance estimates from the YMW16 electron density model rather place the SNR at a distance of ~0.4 kpc. This would correspond to a ~20 pc linear size and a younger age of 104− < 7 × 105 yr, which would be more in line with the nonequilibrium state of the plasma.

Numerical Investigation of Thermohydraulic Characteristics in Supercritical CO2 Natural Circulation Loop with Spatially Varying Temperature

Investigation of thermohydraulic characteristics is highly significant for any natural circulation loop (NCL) applications. The physical properties of supercritical fluids are highly sensitive to temperature when they cross pseudo-critical points. In the current study, steady state thermohydraulic characteristics of NCL with a spatially varying temperature distribution on the source along with different orientations of the source and sink are numerically investigated. A three-dimensional rectangular NCL with a uniform diameter and constant length of source and sink is modeled. The temperature of the sink is held constant, while the temperature of the source varies spatially with local maximum and minimum temperatures. The system performance is investigated for four different operating pressures ranging from 8 to 12 MPa. The mass flow rate is observed to increase with increasing operating pressure for all orientations and heat load distribution at the source. The results also indicate that heat transfer degrades when the fluid crosses the pseudo-critical point. It has been noticed that spatially varying temperature distribution has a maximum of 48% heat transfer variation compared to the constant temperature distribution. Furthermore, a source or sink located in the horizontal leg performs better than the vertical leg.

Development of compact-modulated absorption/emission technique towards micro-gravity sooting flame measurements

To meet the experimental physical limitations on Chinese Space Station (CSS), three compact-modulated absorption/emission (CMAE) implementations are miniaturized progressively from original MAE layout, which are investigated as potential options for simultaneous soot temperature and volume fraction measurements in the axis-symmetric flames. Contrasted with the original MAE technique, a white LED point light source (diameter of ϕ = 8 mm) and a white LED planar light source (rectangle of 200 × 120 mm2) in turns replaces the laser source, by which the light beam homogeneous implementation is significantly simplified. Moreover, a 3-CMOS prism-based camera enables simultaneously recording flame two color radiations that reduces the detecting complexity. It is found that backlight beam intensity should be more than 2.5 times the flame radiation intensity to avoid abnormal extinction coefficient on the flame edge in this configuration. Moreover, the robustness and consistency of the three CMAEs measurements are validated with a standard Santoro’s flame, and low average standard deviation ranges of ±0.04∼±0.06 ppm and ±65.0∼± 96.3 K for soot volume fraction and temperature respectively is evaluated from error propagation assessment. As such, the proposed CMAE-2 and CMAE-3 layouts are promising candidates for high-fidelity flame soot parameters measurements under limited space, weight and power supply on CSS.

Experimental study and newly proposed correlations for maximum ceiling gas temperature rise in tunnel fires with natural ventilation

As a critical factor in tunnel fire safety, previous research on model predictions of the maximum ceiling gas temperature rise under natural ventilation has not demonstrated consistent results. These discrepancies are commonly attributed to variations in tunnel dimensions and materials. To address this issue, an experimental investigation utilizing heptane pool fires with different dimensions was conducted in a model-scale tunnel. The results show that the burning rate increases with an increasing aspect ratio of the fire source for the selected diameter range of 0.078–0.169 m. The flame length was characterized using a modified diameter of the fire source considering the air entrainment, and found that the non-dimensional flame length is 2.4 times the 2/5th power of the non-dimensional heat release rate. Finally, incorporating the concept of flame virtual origin, two different forms of correlations were developed to quantify the maximum ceiling gas temperature rise under different impingement conditions of the fire plume, and the coefficients were determined as 0.065 and 0.215 by numerous experimental results from different studies. The newly proposed models demonstrate good applicability to the fire sources with different dimensions, especially for the rectangular fire source with a large aspect ratio, thus solving the problem of insufficient accuracy of classical models under this condition.

Experimental study on the airflow dynamics and particulate matter emission characteristics of cooking fumes during frying, roasting, and deep-frying

Clarifying the characteristics of thermal plume airflow dynamics and particle characteristics during different cooking processes is helpful for efficiently controlling cooking fumes. In this study, the flow and emission characteristics of cooking fumes produced during frying, roasting, and deep frying were investigated using quantitative schlieren techniques and particulate matter sensors. The results show that frying, roasting, and deep-frying have smaller vortex areas, but different to that produced when simply heating edible oil, with the three cooking scenarios exhibiting plume dispersion angles that are, on average, approximately 20° larger than that observed for the heated-oil case. Furthermore, the emission velocity of the source ranged from 0 to 0.5 m/s for the four cases (within a distance one-times the diameter of the emission source). The velocity of the heated-oil case was generally Gaussian distributed, whereas those of the cooking cases were parabolically distributed. All cases exhibited linear variations in sectional diffusion diameter and flow rate along the vertical direction. The three cooking cases exhibited linearly fitted slopes that are approximately 1.0–2.0-times greater than that of the heated-oil case, which is reflective of more ambient air entrained during cooking. Particles 1–2.5 μm in size were observed for the three cooking cases, while the deep-frying case exhibited an average particulate mass concentration more than twice that observed for the heated-oil, which significantly increases the danger of exposure to oil-fume particles. In summary, detailed cooking-fume data serve as boundary conditions for simulations and provide crucial insight for effectively capturing cooking fumes.

THERMAL SOURCE EFFECT ON THE NATURAL CONVECTION OF A NANOFLUID WITHIN A TRIANGULAR CAVITY

Natural convection is numerically studied in a triangular cavity whose inclined walls that is isothermal at temperature TC, while its base is thermally insulated. The cavity contains a hot isothermal cylindrical heat source TH of diameter D. In this study, we used the nanofluid (water + TiO2). The nanoparticle volume fraction is varied within the range 0.01 ≤ ϕ ≤ 0.05, and the Rayleigh number is set between 103 and 106. The main objective of this study is to explore the impact of nanoparticle concentration, Rayleigh number (Ra), and heat source position (h) on the enhancement of convective thermal transfer. The simulation results show that thermal exchange improves with increasing Ra, heat source diameter, and nanoparticle volume fraction (ϕ).

Experimental investigation on magnetic field strength providing thrust saturation in a magnetic nozzle radiofrequency plasma thruster

Magnetic field strength applied to a magnetic nozzle radiofrequency (rf) plasma thruster having a 10.5 cm diameter source tube is increased up to about 3 kG by pulsing the solenoid current. A target plate is installed at 30 cm downstream of the source and an impulse bit exerted to the target is measured to assess the thrust, where the thrust balance measurement was impossible due to the interaction between the pulsed magnetic fields and the eddy currents on surroundings. Since the diameter of the plasma plume at the target location is larger than the target diameter, a comparison between the thrust balance and target measurements under continuous magnetic field and rf power is performed prior to the pulsed magnetic field experiments, showing that about 65 percent of the plasma momentum is exerted to the target plate. Saturation of the impulse bit, being equivalent to the force multiplied by the rf pulse width, is clearly observed when increasing the magnetic field strength. The magnetic field providing the force saturation is found to be changed by the source diameter, which is qualitatively explained by considering a change in the plasma loss to the source wall in a thruster model containing the particle balance, power balance, and one-dimensional magnetic nozzle models. It is suggested that the magnetic field strength required for optimizing the force, i.e. the thrust, can be reduced when enlarging the source tube diameter.

A Hanbury Brown and Twiss renascence: measurement of photon correlations yields spatio-temporal coherence

Investigations of photon correlations similar to the Hanbury Brown and Twiss experiment are since the advent of quantum optics in the center of both fundamental and application-oriented research. We derive a factorial moment-generating function of the probability distribution of electromagnetic radiation emitted by a source and absorbed by a photodetector from which we calculate an analytical expression for the second-order correlation coefficient g^{(2)} which reflects spatial coherence properties of the emitted light. The measurement of g^{(2)} thus allows to retrieve the spatial coherence parameter of the light source in terms of the combination of source area, source-detector distance, wavelength and detector area. The validity of the concept is proven by investigating g^{(2)} of true thermal light from a Xenon arc lamp and from the sun for various detector areas, in excellent agreement with the theory. Finally, we suggest a novel scheme for determining light source diameters by exploiting the spatially dependent statistics and confirm its validity by exemplary calculations. These results based on radiation thermodynamics and photon statistics give fresh insight into quantum optical properties of classical light sources, photon correlations and photodetection with promising applications perspectives, more than 68 years after the original Hanbury Brown and Twiss experiment.

Comparing burner fire whirls to pool fire whirls

The fire whirl literature largely focuses on studies of whirls generated using pool fires instead of burners. Pool fire whirls probably more closely represent in situ fire whirls as both have a burning rate that depends on the horizontal area of the fuel source. However, in a laboratory setting, working with burners allow for control of all parameters involved in whirl formation, including the independent effects of source diameter and fuel rate. A comparison of the structure and scaling relationships of burner and pool fire whirls is presented here, so that the impact of using a burner or pool fire whirl in an experiment can be understood. It is shown that, in addition to being similarly tall and thin, the whirls have similar precession diameters, similarly structured air entrainment regions, and have azimuthal velocity profiles that are well-described by a Burgers vortex both inside and outside the whirl core. However, the depths of the air entrainment regions relative to whirl height are different, where the pool whirls have a region of slow axial flow above the air entrainment region that the burner whirls do not, and the whirls’ circulation and height follow different scaling relationships. The primary source of these differences is the fuel source itself, where, in contrast to the pool fire, the burner whirl heat release rate is independent of the size of the fuel source.

The Core Starbursts of the Galaxy NGC 3628: Radio Very Long Baseline Interferometry and X-Ray Studies

We present radio very long baseline interferometry (VLBI) and X-ray studies of the starburst galaxy NGC 3628. The VLBI observation at 1.5 GHz reveals seven compact (0.7−7 pc) radio sources in the central ∼250 pc region of NGC 3628. Based on their morphology, high radio-brightness temperatures (105–107 K), and steep radio spectra, none of these seven sources can be associated with active galactic nuclei (AGNs); instead, they can be identified as supernova remnants (SNRs), with three of them appearing consistent with partial shells. Notably, one of them (W2) is likely a nascent radio supernova (SN) and appears to be consistent with the star formation rate of NGC 3628 when assuming a canonical initial mass function. The VLBI observation provides the first precise measurement of the diameter of the radio sources in NGC 3628, which allow us to fit a well-constrained radio surface brightness—diameter (Σ–D) correlation by including the detected SNRs. Furthermore, future VLBI observations can be conducted to measure the expansion velocity of the detected SNRs. In addition to our radio VLBI study, we analyze Chandra and XMM-Newton spectra of NGC 3628. The spectral fitting indicates that the SNR activities could well account for the observed X-ray emissions. Along with the Chandra X-ray image, it further reveals that the X-ray emission is likely maintained by the galactic-scale outflow triggered by SN activities. These results provide strong evidence that SN-triggered activities play a critical role in generating both radio and X-ray emissions in NGC 3628.

Beam optics simulation of the ion injector for sodium Beam Emission Spectroscopy (Na-BES) on EAST

To upgrade the Li-BES to Na-BES on Experimental Advanced Superconducting Tokamak (EAST), a high-brightness and stable sodium (Na) ion source is developed, and the performance of Na ion beam optics is simulated by the COMSOL Multiphysics. The porous tungsten disk with 70% porosity and filled with albite Na2O·Al2O3·6SiO2 is successfully developed as the Na ion source. The extracted current density of the Na-beam increases with the extraction voltage, and its maximum current can reach 9 mA with the ion source diameter of 20 mm. The lifetime of the Na ion source is evaluated to be 63 mAh, which is much longer than that of the Li ion source. The simulation shows that the preferable distances among the ion source (or anode electrode), extractor and puller to get the well-focused beam are x puller - x extractor ∼ 0.06 m and x extractor - x ion source ∼ 0.02 m. Further simulation with these optimized distances determines the extraction voltage and ion source size for good beam performance. In addition, the simulation shows the beam divergence angle decreases by more than 40% by optimizing the Einzel voltage to 5 kV, suggesting an excellent focusing property of the Einzel lens. These works provide the basis and the design references for the Na-BES development on EAST.

Experimental investigation of degree of cross-polarization for an electromagnetic Gaussian-Schell model beam.

We investigate the properties of the degree of cross-polarization (DOCP) for an electromagnetic Gaussian-Schell model (EMGSM) beam in the radial direction of the cross section of the beam. The coherence and polarization features of a partially coherent light beam are engineered to construct the isotropic and non-isotropic EMGSM beams, and the resulting changes in the DOCP are examined. For experimental realization, a double-slit interferometer is utilized at the output to probe the coherence properties for different polarization components across the beam diameter of an electromagnetic source. Experimental observations infer that variation in DOCP does not become apparent for isotropic coherence widths in the orthogonal polarization directions, whereas the variation can be apparent only once both the coherence widths are distinct. Furthermore, experimentally, a special case is also investigated for which the value of DOCP goes beyond unity. The DOCP finds application in areas such as second-order intensity interference, imaging, and characterization of non-homogeneously polarized beams.

A physical model on the flame structure of vertical downward turbulent jet fires

This work explored the flame geometrical characteristics of vertical downward turbulent jet fires in still air, whose flame buoyancy was opposite to its initial momentum. Experiments were carried out under varied fuel supply rates with propane as fuel. Three circular nozzles having diameters of 3, 5 and 7 mm were employed. CFD simulation to show the combustion structure inside the flame was conducted in the work, contributing to proposing a new physical model. The inner flow field and average mixture fraction of a downward jet fire have been revealed and the CFD result was validated by experimental data. A downward jet fire can be distinguished in three regions: the downward core flow region where the initial flame momentum is opposed by buoyancy, the flow reversal dome region where the momentum reverses direction, and the upward combusting flow region, which surrounds the core, dominated by buoyancy. Three basic flame morphologic lengths of the downward jet fires were measured, namely the flame downward length below the nozzle, the flame width, and the total flame height. The inherent differences between downward, upward and horizontal jet, caused by the momentum direction, were discussed by comparing the flame sizes of these three types of jet flames. A physical model considering the initial downward volumetric momentum, the flame buoyancy and the air entrainment volume until complete combustion occurs was raised to depict the flame geometric characteristics derived from three characteristic length scales, namely a momentum-buoyancy competition length scale, a flow-rate length scale linked with the source diameter and a total combustion buoyancy length scale. All measured experimental flame lengths were normalized using dimensionless groups (such as LmLq and Sṁf/ρ∞g′LmLm2) derived by these three length scales. The geometric properties of downward jet fires were shown to be well modelled by the proposed non-dimensional groups which were different from previously used length scales in the literature.

Analysis of liquid samples by Low-Temperature Plasma Ionization Source-ion mobility spectrometry

In this study, liquid pharmaceutical samples are analyzed using an ion mobility spectrometer (IMS) with the Low-Temperature Plasma Ionization Source (LTPI) for the first time, overcoming limitations for this system due to intense interaction with IMS cell without sample pre-preparation. The direct sample introduction or newer methods that were presented in recent years in the LTP-MS are useful in mass spectroscopy, but these methods are incompetent in IMS. In new LTP-IMS, first, the sample is vaporized, then transferred to the ionization source by the carrier gas, and finally ionized. The new method has several salient characteristics as follows in comparison to the other similar devices. A new efficient way for sample entering which needs less amount of sample, does not waste it and ionizes liquid samples without any preparation or pre-extraction because the ionization source can vaporize, desorb, and ionize the samples simultaneously. In this work, the IMS cell, LTP, and sample introduction system must sync together, so they were redesigned to eliminate incompatibilities. Afterward, to achieve the best response, before evaluating the device, all parameters consist of gas flow, voltage, frequency, exhaust diameter of source, and IMS cell parameters were optimized. Then several pharmaceutical samples, including Papaverine, Codeine, Caffeine, and Diethylamine were analyzed to evaluate the qualitative and quantitative characteristics of the device. The samples were dissolved in methanol and detected in a few seconds, with a low detection limit of 41.75 ng for Codeine, 7.50 ng, and 8.25 ng for Caffeine and Papaverine, respectively.

Crystal response measurement of the x-ray transmission crystals used by the Imaging Spectroscopy Snout at the National Ignition Facility.

The Imaging Spectroscopy Snout (ISS) used at the National Ignition Facility is able to simultaneously collect neutron pinhole images, 1D spatially resolved x-ray spectra, and time resolved x-ray pinhole images. To measure the x-ray spectra, the ISS can be equipped with up to four different transmission crystals, each offering different energy ranges from ∼7.5 to ∼12keV and different resolutions. Characterizing and calibrating such instruments is of paramount importance in order to extract meaningful results from experiments. More specifically, we characterized different ISS transmission-type alpha-Quartz crystals by measuring their responses as a function of photon energy, from which we inferred the angle-integrated reflectivity for each crystal's working reflections. These measurements were made at the Lawrence Livermore National Laboratory calibration station dedicated to the characterization of x-ray spectrometers. The sources used covered a wide x-ray range-from a few to 30keV; the source diameter was ∼0.6mm. The experimental results are discussed alongside theoretical calculations using the pyTTE model.

Genetic control of source-sink relationships in grain sorghum.

QTL hotspots identified for selected source-sink-related traits provide the opportunity for pyramiding favorable alleles for improving sorghum productivity under diverse environments. A sorghum bi-parental mapping population was evaluated under six different environments at Hays and Manhattan, Kansas, USA, in 2016 and 2017, to identify genomic regions controlling source-sink relationships. The population consisted of 210 recombinant inbred lines developed from US elite post-flowering drought susceptible (RTx430) and a known post-flowering drought tolerant cultivar (SC35). Selected physiological traits related to source (effective quantum yield of photosystem II and chlorophyll index), sink (grain yield per panicle) and panicle neck diameter were recorded during grain filling. The results showed strong phenotypic and genotypic association between panicle neck diameter and grain yield per panicle during mid-grain filling and at maturity. Multiple QTL model revealed 5-12 including 2-5 major QTL for each trait. Among them 3, 7 and 8 QTL for quantum yield, panicle neck diameter and chlorophyll index, respectively, have not been identified previously in sorghum. Phenotypic variation explained by QTL identified across target traits ranged between 5.5 and 25.4%. Panicle neck diameter and grain yield per panicle were positively associated, indicating the possibility of targeting common co-localized QTL to improve both traits simultaneously through marker-assisted selection. Three major QTL hotspots, controlling multiple traits were identified on chromosome 1 (52.23-61.18Mb), 2 (2.52-11.43Mb) and 3 (1.32-3.95Mb). The identified genomic regions and underlying candidate genes can be utilized in pyramiding favorable alleles for improving source-sink relationships in sorghum under diverse environments.

A sensitivity analysis applied to SPRAY and CALPUFF models when simulating dispersion from industrial fires

This paper discusses a hypothetical case study in which SPRAY and CALPUFF dispersion models are applied to the simulation of an incidental fire. For this type of accident, source features are typically not directly measurable, thus making their definition critical. The choice of some model-specific parameters is another critical issue, since clear indications are rarely available in guidelines. The aim of this work is to compare how pollutant concentrations simulated with the two models are affected by changing these two sets of data (i.e. parameters related to the emission source and model specific parameters), thus performing a sensitivity study to identify the most influential variables. The most relevant outcome is that sensitivities of the two models are generally comparable, except for the source diameter: if the SPRAY model is applied with the specific fire source option, then the concentrations result almost independent from this parameter. Conversely, when considering other source-types, the concentrations vary up to ± 60% within the selected uncertainty range.

Land use impacts on Boswellia dalzielii Hutch. an African frankincense tree in Burkina Faso

Boswellia dalzielii Hutch., an African frankincense tree, is a socio-economically important aromatic and medicinal tree. It is currently threatened by uncontrolled exploitation, and therefore requires action to ensure its sustainable management. This study assessed the population structure and regeneration of its natural stands across three land use types in Burkina Faso: woodlands, fallows and farmlands. Sixty, fifty and fifty 50 m × 20 m plots were established respectively in woodlands, fallows and farmlands. All the plots were surveyed for adult tree (dbh ≥ 5 cm) density, dbh, total height and health conditions. Data on regeneration density (dbh < 5 cm), source (generative, stem shoots, suckers), total height and collar diameter were also collected. The results show similar total tree heights (7.0 m-9.0 m) but significantly (p < 0.05) smaller tree dbh in woodlands (mean ± SD: 20.5 ± 0.49 cm) and fallows (29.3 ± 0.64 cm) than in farmlands (32.8 ± 0.15 cm). Adult tree density (trees/ha) was 1.3 and 2.7 times higher in woodlands (82.37 ± 6.57) than in fallows (62.00 ± 3.98) and farmlands (30.02 ± 1.63), respectively. The density of regeneration in woodlands was 28 and 6 times higher than in fallows and farmlands, respectively. The majority (> 50%) of regenerating plants were suckers and no seedling regeneration was found in farmlands. The distribution of trees in diameter classes was J-shaped in woodlands, bell-shaped in farmlands and positive asymmetric in fallows, indicating recruitment bottlenecks. We found that 80.18% of individuals encountered were unhealthy. Intensive debarking and cutting were the main threats to the species and no conservation strategy was in place in the study region. We suggest measures to reduce intensive debarking and cutting, which should contribute to better management of the species.

Quantitative measurement of pioglitazone in neoplastic and normal tissues by AP-MALDI mass spectrometry imaging

Pioglitazone is a Peroxisome Proliferator-Activated Receptor (PPAR) agonist of the thiazolidinedione class of compounds with promising anticancer activity. An innovative quantitative mass spectrometry imaging (MSI) method and a HPLC-UV method were developed and validated to investigate its distribution in tumor and liver tissues. The MSI method is based on stable isotope normalization and resulted highly specific and sensitive (0.2 pmol/spot). The correct identification of the drug ion signal is confirmed by MS/MS analysis on tissue. The method shows an optimal lateral resolution (25 μm) relying on the ionization efficiency and fine laser diameter of the atmospheric pressure MALDI source. The HPLC-UV method is simple and straightforward involving quick protein precipitation and shows good sensitivity (50ng/sample) using a small starting volume of biological sample. Thus, it is applicable to samples obtained from both preclinical models and clinical surgical procedures. MSI and HPLC-UV assays were validated assessing linearity, intra- and inter-day precision and accuracy, limit of quantification, selectivity and recovery. These are the first methods developed and validated for the analysis of pioglitazone in tissues, and they were applied successfully to myxoid liposarcoma xenograft-bearing mice, which received clinically relevant drug doses. Pioglitazone was measured by either method in sections of tumor and liver 2, 6 and 24 h post-treatment. Drug distribution was relatively homogeneous.