Elucidation of the controlled-release behavior of metoprolol succinate from directly compressed xanthan gum-chitosan polymers: computational and experimental studies

The development and evaluation of a controlled-release (CR) pharmaceutical solid dosage form comprising xanthan gum (XG), low molecular weight chitosan (LCS) and metoprolol succinate (MS) is reported. The research is, partly, based upon the utilization of computational tools; in this case molecular dynamics simulations (MDs) and response surface method (RSM), in order to underpin the design/prediction and to minimize the experimental work required to achieve the desired pharmaceutical outcomes. The capability of the system to control the release of MS was studied as a function of LCS (% w/w) and total polymer (LCS and XG) to drug ratio (P:D) at different tablet tensile strengths. MDs trajectories, obtained by using different ratios of XG:LCS as well as XG and high molecular weight CS (HCS), showed that the driving force for the interaction between XG and LCS is electrostatic in nature, the most favourable complex is formed when LCS is used at 15 % (w/w) and, importantly, that the interaction between XG and LCS is more favourable than that between XG and HCS. RSM outputs revealed that the release of the drug from the LCS/XG matrix is highly dependent on both the % LCS and the P:D ratio and that the required CR effect can be achieved when using weight fractions of LCS ≤ 20% and P:D ratios ≥ 2.6:1. Results obtained from in-vitro drug release and swelling studies on the prepared tablets showed that using LCS at the weight fractions suggested by MDs and RSM data plays a major role in overcoming the high sensitivity of the controlled drug release effect of XG on ionic strength and pH changes of the dissolution media. In addition, it was found that polymer relaxation is the major contributor to the release of MS from LCS-XG tablets. Using Raman spectroscopy, MS was shown to be localized more in the core of the tablets at the initial stages of dissolution due to film formation between LCS and XG on the tablet surface which prevents excess water penetration into the matrix. In the later stages of the dissolution process, the film starts to dissolve/erode allowing full tablet hydration and a uniform drug distribution in the swollen tablet

Seismic empirical relations for the Tellian Atlas, North Africa, and their usefulness for seismic risk assessment

Seismic events that occurred during the past half century in the Tellian Atlas, North Africa, are used to establish fundamental seismic empirical relations, tying earthquake magnitude to source parameters (seismic moment, fault plane area, maximal displacement along the fault, and fault plane length). Those empirical relations applied to the overall seismicity from 1716 to present are used to transform the magnitude (or intensity) versus time distribution into (1) cumulative seismic moment versus time, and (2) cumulative displacements versus time. Both of those parameters as well as the computed seismic moment rate, the strain rate along the Tellian Atlas strike, and various other geological observations are consistent with the existence, in the Tellian Atlas, of three distinct active tectonic blocks. These blocks are seismically decoupled from each other, thus allowing consideration of the seismicity as occurring in three different distinct seismotectonic blocks. The cumulative displacement versus time from 1900 to present for each of these tectonic blocks presents a remarkable pattern of recurrence time intervals and precursors associated with major earthquakes. Indeed, most major earthquakes that occurred in these three blocks might have been predicted in time. The Tellian Atlas historical seismicity from the year 881 to the present more substantially confirms these observations, in particular for the western block of the Tellian Atlas. Theoretical determination of recurrence time intervals for the Tellian Atlas large earthquakes using Molnar and Kostrov formalisms is also consistent with these observations. Substantial observations support the fact that the western and central Tellian Atlas are currently at very high seismic risk, in particular the central part. Indeed, most of the accumulated seismic energy in the central Tellian Atlas crust has yet to be released, despite the occurrence of the recent destructive May 2003 Boumerdes earthquake (M (w) = 6.8). The accumulated seismic energy is equivalent to a magnitude 7.6 earthquake. In situ stress and geodetic measurements, as well as other geophysical field data measurements, are now required to practically check the validity of those observations

Impact of particle aggregation on vertical fluxes of organic matter

Particles sinking out of the euphotic zone are important vehicles of carbon export from the surface ocean. Most of the particles produce heavier aggregates by coagulating with each other before they sink. We implemented an aggregation model into the biogeochemical model of Regional Oceanic Modelling System (ROMS) to simulate the distribution of particles in the water column and their downward transport in the Northwest African upwelling region. Accompanying settling chamber, sediment trap and particle camera measurements provide data for model validation. In situ aggregate settling velocities measured by the settling chamber were around 55 m d−1. Aggregate sizes recorded by the particle camera hardly exceeded 1 mm. The model is based on a continuous size spectrum of aggregates, characterised by the prognostic aggregate mass and aggregate number concentration. Phytoplankton and detritus make up the aggregation pool, which has an averaged, prognostic and size dependent sinking. Model experiments were performed with dense and porous approximations of aggregates with varying maximum aggregate size and stickiness as well as with the inclusion of a disaggregation term. Similar surface productivity in all experiments has been generated in order to find the best combination of parameters that produce measured deep water fluxes. Although the experiments failed to represent surface particle number spectra, in the deep water some of them gave very similar slope and spectrum range as the particle camera observations. Particle fluxes at the mesotrophic sediment trap site off Cape Blanc (CB) have been successfully reproduced by the porous experiment with disaggregation term when particle remineralisation rate was 0.2 d−1. The aggregationdisaggregation model improves the prediction capability of the original biogeochemical model significantly by giving much better estimates of fluxes for both upper and lower trap. The results also point to the need for more studies to enhance our knowledge on particle decay and its variation and to the role that stickiness play in the distribution of vertical fluxes

TRISHNA: a high spatio-temporal resolution Indian-French spatial mission for TIR Earth observation

The climate change context, along with the increasing scarcity and deteriorating quality of the water resource leads to monitor different components of the water cycle. A particular attention has to be paid to some areas, particularly, agricultural lands which represent about 70% of the water consumption, and coastal areas subject to strong interactions with land. Thermal infrared (TIR) data from space are well adapted to these purposes, but the spatial variability of the surface requires that the complexity of both physical and biological processes involved must be assessed at a smaller scale which corresponds to the scale at which decisions concerning water management or implementation of policies devoted to the mitigation of climate change effect are effective. In addition, surface fluxes show short-time scale variability, which requires frequent observations to be done. The need of space borne systems combining both high spatial resolution and high revisit frequency in thermal infrared (TIR), which do not exist today, is now largely recognized by the scientific community and end-users, especially as SENTINEL and RESOURCESAT missions now provide high quality complementary data in the optical domain. To fill this gap a project, TRISHNA (Thermal infraRed Imaging Satellite for High-resolution Natural resource Assessment), is currently in the feasibility assessment phase, conducted by the French Space Agency (CNES) and the Indian Space Research Organization (ISRO).Two scientific objectives drive the mission specifications, (i) monitoring of ecosystem stress of the continental biosphere and of water use with applications to agriculture and hydrology, and (ii) monitoring of coastal and continental waters. Four complementary goals enlarge the community aggregated around the project: (iii) urban microclimates monitoring (urban heat islands, mitigation of heat waves effects…), (iv) applications to Solid Earth/geology (detection of thermal anomalies, volcanology, peat fires…), (v) cryosphere monitoring (glaciers, polar regions…), and (vi) applications to atmosphere (water content, clouds…). These objectives and the expected applications will first be briefly reviewed at the symposium.The main mission specifications will then be presented. Additionally to previous work conducted to consolidate the revisit and resolution specifications, emphasis will be put on recent studies made for inventorying factors possibly perturbing surface temperature measurements. Significant advances obtained for characterizing and modelling TIR directional anisotropy and thermal hot spot effects will first be described and their impact on the choice of orbit discussed. Similarly, an original study of the impact of atmospheric turbulence on the accuracy of LST -largely ignored by the community till date- will be presented; it reinforces the need of high revisit, and allows to estimate the errors on LST measurements. An overpass time in the early afternoon, around 13:00 LST has been carefully justified to cope with the different objectives of the mission and to optimize the accuracy on retrieved fluxes. A baseline spectral configuration of 4 TIR channels within the range 8 - 12 µm is under study, which makes possible implementing both split-window and temperature-emissivity separation algorithms. The main specifications of VNIR instrument embarked aboard the same platform are presented, and the need of 6 bands, 4 in the VNIR (blue, green, red, near infrared at 485, 555, 670, 860 nm) and 2 in the SWIR (1.38 and 1.61 µm) justified. To cope with the requirement of global coverage at Equator with a single satellite, a revisit of 3 days is selected. The nadir resolution of 50 m is binned at 1 km over open ocean. The instrumental studies undertaken will be briefly presented.The programmatic context of existing missions will be analyzed, only TRISHNA and the ESA LSTM mission providing high spatio-temporal capacities. The forthcoming phases of the CNES-ISRO TRISHNA project will finally be briefly mentioned, for a launch date foreseen at the 2024-2025 horizon

TRISHNA: a high spatio-temporal resolution Indian-French spatial mission for TIR Earth observation

The climate change context, along with the increasing scarcity and deteriorating quality of the water resource leads to monitor different components of the water cycle. A particular attention has to be paid to some areas, particularly, agricultural lands which represent about 70% of the water consumption, and coastal areas subject to strong interactions with land. Thermal infrared (TIR) data from space are well adapted to these purposes, but the spatial variability of the surface requires that the complexity of both physical and biological processes involved must be assessed at a smaller scale which corresponds to the scale at which decisions concerning water management or implementation of policies devoted to the mitigation of climate change effect are effective. In addition, surface fluxes show short-time scale variability, which requires frequent observations to be done. The need of space borne systems combining both high spatial resolution and high revisit frequency in thermal infrared (TIR), which do not exist today, is now largely recognized by the scientific community and end-users, especially as SENTINEL and RESOURCESAT missions now provide high quality complementary data in the optical domain. To fill this gap a project, TRISHNA (Thermal infraRed Imaging Satellite for High-resolution Natural resource Assessment), is currently in the feasibility assessment phase, conducted by the French Space Agency (CNES) and the Indian Space Research Organization (ISRO).Two scientific objectives drive the mission specifications, (i) monitoring of ecosystem stress of the continental biosphere and of water use with applications to agriculture and hydrology, and (ii) monitoring of coastal and continental waters. Four complementary goals enlarge the community aggregated around the project: (iii) urban microclimates monitoring (urban heat islands, mitigation of heat waves effects…), (iv) applications to Solid Earth/geology (detection of thermal anomalies, volcanology, peat fires…), (v) cryosphere monitoring (glaciers, polar regions…), and (vi) applications to atmosphere (water content, clouds…). These objectives and the expected applications will first be briefly reviewed at the symposium.The main mission specifications will then be presented. Additionally to previous work conducted to consolidate the revisit and resolution specifications, emphasis will be put on recent studies made for inventorying factors possibly perturbing surface temperature measurements. Significant advances obtained for characterizing and modelling TIR directional anisotropy and thermal hot spot effects will first be described and their impact on the choice of orbit discussed. Similarly, an original study of the impact of atmospheric turbulence on the accuracy of LST -largely ignored by the community till date- will be presented; it reinforces the need of high revisit, and allows to estimate the errors on LST measurements. An overpass time in the early afternoon, around 13:00 LST has been carefully justified to cope with the different objectives of the mission and to optimize the accuracy on retrieved fluxes. A baseline spectral configuration of 4 TIR channels within the range 8 - 12 µm is under study, which makes possible implementing both split-window and temperature-emissivity separation algorithms. The main specifications of VNIR instrument embarked aboard the same platform are presented, and the need of 6 bands, 4 in the VNIR (blue, green, red, near infrared at 485, 555, 670, 860 nm) and 2 in the SWIR (1.38 and 1.61 µm) justified. To cope with the requirement of global coverage at Equator with a single satellite, a revisit of 3 days is selected. The nadir resolution of 50 m is binned at 1 km over open ocean. The instrumental studies undertaken will be briefly presented.The programmatic context of existing missions will be analyzed, only TRISHNA and the ESA LSTM mission providing high spatio-temporal capacities. The forthcoming phases of the CNES-ISRO TRISHNA project will finally be briefly mentioned, for a launch date foreseen at the 2024-2025 horizon

TRISHNA: a high spatio-temporal resolution Indian-French spatial mission for TIR Earth observation

The climate change context, along with the increasing scarcity and deteriorating quality of the water resource leads to monitor different components of the water cycle. A particular attention has to be paid to some areas, particularly, agricultural lands which represent about 70% of the water consumption, and coastal areas subject to strong interactions with land. Thermal infrared (TIR) data from space are well adapted to these purposes, but the spatial variability of the surface requires that the complexity of both physical and biological processes involved must be assessed at a smaller scale which corresponds to the scale at which decisions concerning water management or implementation of policies devoted to the mitigation of climate change effect are effective. In addition, surface fluxes show short-time scale variability, which requires frequent observations to be done. The need of space borne systems combining both high spatial resolution and high revisit frequency in thermal infrared (TIR), which do not exist today, is now largely recognized by the scientific community and end-users, especially as SENTINEL and RESOURCESAT missions now provide high quality complementary data in the optical domain. To fill this gap a project, TRISHNA (Thermal infraRed Imaging Satellite for High-resolution Natural resource Assessment), is currently in the feasibility assessment phase, conducted by the French Space Agency (CNES) and the Indian Space Research Organization (ISRO).Two scientific objectives drive the mission specifications, (i) monitoring of ecosystem stress of the continental biosphere and of water use with applications to agriculture and hydrology, and (ii) monitoring of coastal and continental waters. Four complementary goals enlarge the community aggregated around the project: (iii) urban microclimates monitoring (urban heat islands, mitigation of heat waves effects…), (iv) applications to Solid Earth/geology (detection of thermal anomalies, volcanology, peat fires…), (v) cryosphere monitoring (glaciers, polar regions…), and (vi) applications to atmosphere (water content, clouds…). These objectives and the expected applications will first be briefly reviewed at the symposium.The main mission specifications will then be presented. Additionally to previous work conducted to consolidate the revisit and resolution specifications, emphasis will be put on recent studies made for inventorying factors possibly perturbing surface temperature measurements. Significant advances obtained for characterizing and modelling TIR directional anisotropy and thermal hot spot effects will first be described and their impact on the choice of orbit discussed. Similarly, an original study of the impact of atmospheric turbulence on the accuracy of LST -largely ignored by the community till date- will be presented; it reinforces the need of high revisit, and allows to estimate the errors on LST measurements. An overpass time in the early afternoon, around 13:00 LST has been carefully justified to cope with the different objectives of the mission and to optimize the accuracy on retrieved fluxes. A baseline spectral configuration of 4 TIR channels within the range 8 - 12 µm is under study, which makes possible implementing both split-window and temperature-emissivity separation algorithms. The main specifications of VNIR instrument embarked aboard the same platform are presented, and the need of 6 bands, 4 in the VNIR (blue, green, red, near infrared at 485, 555, 670, 860 nm) and 2 in the SWIR (1.38 and 1.61 µm) justified. To cope with the requirement of global coverage at Equator with a single satellite, a revisit of 3 days is selected. The nadir resolution of 50 m is binned at 1 km over open ocean. The instrumental studies undertaken will be briefly presented.The programmatic context of existing missions will be analyzed, only TRISHNA and the ESA LSTM mission providing high spatio-temporal capacities. The forthcoming phases of the CNES-ISRO TRISHNA project will finally be briefly mentioned, for a launch date foreseen at the 2024-2025 horizon

TRISHNA: a high spatio-temporal resolution Indian-French spatial mission for TIR Earth observation

The climate change context, along with the increasing scarcity and deteriorating quality of the water resource leads to monitor different components of the water cycle. A particular attention has to be paid to some areas, particularly, agricultural lands which represent about 70% of the water consumption, and coastal areas subject to strong interactions with land. Thermal infrared (TIR) data from space are well adapted to these purposes, but the spatial variability of the surface requires that the complexity of both physical and biological processes involved must be assessed at a smaller scale which corresponds to the scale at which decisions concerning water management or implementation of policies devoted to the mitigation of climate change effect are effective. In addition, surface fluxes show short-time scale variability, which requires frequent observations to be done. The need of space borne systems combining both high spatial resolution and high revisit frequency in thermal infrared (TIR), which do not exist today, is now largely recognized by the scientific community and end-users, especially as SENTINEL and RESOURCESAT missions now provide high quality complementary data in the optical domain. To fill this gap a project, TRISHNA (Thermal infraRed Imaging Satellite for High-resolution Natural resource Assessment), is currently in the feasibility assessment phase, conducted by the French Space Agency (CNES) and the Indian Space Research Organization (ISRO).Two scientific objectives drive the mission specifications, (i) monitoring of ecosystem stress of the continental biosphere and of water use with applications to agriculture and hydrology, and (ii) monitoring of coastal and continental waters. Four complementary goals enlarge the community aggregated around the project: (iii) urban microclimates monitoring (urban heat islands, mitigation of heat waves effects…), (iv) applications to Solid Earth/geology (detection of thermal anomalies, volcanology, peat fires…), (v) cryosphere monitoring (glaciers, polar regions…), and (vi) applications to atmosphere (water content, clouds…). These objectives and the expected applications will first be briefly reviewed at the symposium.The main mission specifications will then be presented. Additionally to previous work conducted to consolidate the revisit and resolution specifications, emphasis will be put on recent studies made for inventorying factors possibly perturbing surface temperature measurements. Significant advances obtained for characterizing and modelling TIR directional anisotropy and thermal hot spot effects will first be described and their impact on the choice of orbit discussed. Similarly, an original study of the impact of atmospheric turbulence on the accuracy of LST -largely ignored by the community till date- will be presented; it reinforces the need of high revisit, and allows to estimate the errors on LST measurements. An overpass time in the early afternoon, around 13:00 LST has been carefully justified to cope with the different objectives of the mission and to optimize the accuracy on retrieved fluxes. A baseline spectral configuration of 4 TIR channels within the range 8 - 12 µm is under study, which makes possible implementing both split-window and temperature-emissivity separation algorithms. The main specifications of VNIR instrument embarked aboard the same platform are presented, and the need of 6 bands, 4 in the VNIR (blue, green, red, near infrared at 485, 555, 670, 860 nm) and 2 in the SWIR (1.38 and 1.61 µm) justified. To cope with the requirement of global coverage at Equator with a single satellite, a revisit of 3 days is selected. The nadir resolution of 50 m is binned at 1 km over open ocean. The instrumental studies undertaken will be briefly presented.The programmatic context of existing missions will be analyzed, only TRISHNA and the ESA LSTM mission providing high spatio-temporal capacities. The forthcoming phases of the CNES-ISRO TRISHNA project will finally be briefly mentioned, for a launch date foreseen at the 2024-2025 horizon

TRISHNA: an Indo-French space mission to study the thermography of the Earth at fine spatio-temporal resolution.

International audienc

TRISHNA: an Indo-French space mission to study the thermography of the Earth at fine spatio-temporal resolution.

International audienc

TRISHNA: a high spatio-temporal resolution Indian-French spatial mission for TIR Earth observation

The climate change context, along with the increasing scarcity and deteriorating quality of the water resource leads to monitor different components of the water cycle. A particular attention has to be paid to some areas, particularly, agricultural lands which represent about 70% of the water consumption, and coastal areas subject to strong interactions with land. Thermal infrared (TIR) data from space are well adapted to these purposes, but the spatial variability of the surface requires that the complexity of both physical and biological processes involved must be assessed at a smaller scale which corresponds to the scale at which decisions concerning water management or implementation of policies devoted to the mitigation of climate change effect are effective. In addition, surface fluxes show short-time scale variability, which requires frequent observations to be done. The need of space borne systems combining both high spatial resolution and high revisit frequency in thermal infrared (TIR), which do not exist today, is now largely recognized by the scientific community and end-users, especially as SENTINEL and RESOURCESAT missions now provide high quality complementary data in the optical domain. To fill this gap a project, TRISHNA (Thermal infraRed Imaging Satellite for High-resolution Natural resource Assessment), is currently in the feasibility assessment phase, conducted by the French Space Agency (CNES) and the Indian Space Research Organization (ISRO).Two scientific objectives drive the mission specifications, (i) monitoring of ecosystem stress of the continental biosphere and of water use with applications to agriculture and hydrology, and (ii) monitoring of coastal and continental waters. Four complementary goals enlarge the community aggregated around the project: (iii) urban microclimates monitoring (urban heat islands, mitigation of heat waves effects…), (iv) applications to Solid Earth/geology (detection of thermal anomalies, volcanology, peat fires…), (v) cryosphere monitoring (glaciers, polar regions…), and (vi) applications to atmosphere (water content, clouds…). These objectives and the expected applications will first be briefly reviewed at the symposium.The main mission specifications will then be presented. Additionally to previous work conducted to consolidate the revisit and resolution specifications, emphasis will be put on recent studies made for inventorying factors possibly perturbing surface temperature measurements. Significant advances obtained for characterizing and modelling TIR directional anisotropy and thermal hot spot effects will first be described and their impact on the choice of orbit discussed. Similarly, an original study of the impact of atmospheric turbulence on the accuracy of LST -largely ignored by the community till date- will be presented; it reinforces the need of high revisit, and allows to estimate the errors on LST measurements. An overpass time in the early afternoon, around 13:00 LST has been carefully justified to cope with the different objectives of the mission and to optimize the accuracy on retrieved fluxes. A baseline spectral configuration of 4 TIR channels within the range 8 - 12 µm is under study, which makes possible implementing both split-window and temperature-emissivity separation algorithms. The main specifications of VNIR instrument embarked aboard the same platform are presented, and the need of 6 bands, 4 in the VNIR (blue, green, red, near infrared at 485, 555, 670, 860 nm) and 2 in the SWIR (1.38 and 1.61 µm) justified. To cope with the requirement of global coverage at Equator with a single satellite, a revisit of 3 days is selected. The nadir resolution of 50 m is binned at 1 km over open ocean. The instrumental studies undertaken will be briefly presented.The programmatic context of existing missions will be analyzed, only TRISHNA and the ESA LSTM mission providing high spatio-temporal capacities. The forthcoming phases of the CNES-ISRO TRISHNA project will finally be briefly mentioned, for a launch date foreseen at the 2024-2025 horizon