Comprehensive review of morphological adaptations and conservation strategies of cactiform succulents: A case study of Euphorbia species in arid ecosystems

Cactiform succulents, belonging to the Euphorbia genus, are distinctive species found in the arid and semi-arid ecosystems of Macaronesia and the Arabian Peninsula. Resembling cacti in appearance, they exhibit unique morphological characteristics, such as succulent, green-stemmed structures with ribs, accompanied by a pair of stipular spines. These plants have evolved to thrive in well-draining substrates, including both surface and rocky soils, potentially as an adaptive strategy to combat edaphic drought conditions. Although initially associated solely with arid and desert environments, it is important to note that these cactiform succulents are not exclusively specialized for prolonged dry periods. Rather, they demonstrate morphological adaptations that help them endure arid conditions. The primary objective of this review is to provide an up-to-date synthesis of knowledge concerning cactiform succulents within the Euphorbia genus. It aims to underscore their capacity to flourish in both arid and semi-arid zones, while underscoring the pressing conservation challenges that threaten these plants with degradation and potential extinction. The prevailing climatic conditions, marked by extended and recurrent droughts exacerbated by escalating temperatures, climate fluctuations, and escalating human impact, collectively pose a formidable obstacle to conserving these cactiform succulents and their respective ecosystems. All these threats jeopardize these invaluable natural resources, which hold multifaceted significance spanning environmental, socio-economic, and medicinal domains

Modeling and experimental investigation of the close-spaced vapor transport process for the growth of CuIn(S 0,4 Se 0,6 ) 2 thin films

International audienceThis paper reports the prediction of optimal conditions to grow good quality crystalline thin films using the Close-Spaced Vapor Transport process. A new configuration of the horizontal reactor is used and presented. A thermodynamic model is proposed for the Cu-In-S-Se-I system to describe the deposition of CuIn(S0,4Se0,6)2(CISS) compound. The simulation was performed using the SOLGASMIX software which gives the composition of the chemical system at the thermodynamic equilibrium. The model is based on the minimization of the Gibbs energy of the defined chemical system. The present study has allowed us to determine the influence of the source temperature (TS) and iodine pressure (PI2) on the growth of CISS thin films. The different compounds of the solid phase were predicted for various TS and PI2 values. The conditions of stoichiometric and quasi-stoichiometric deposition are 475 ≤ TS ≤ 525 °C and PI2 ≤ 3 kPa. Some deduced conditions from the theoretical prediction were tested experimentally. The CISS samples grown have been analyzed by X-ray diffraction and scanning electron microscope. The thin films, deposited in optimal conditions, are stoichiometric

Analysis of electrical conduction mechanism in the high temperature range of the nanostructured photoabsorber Cu 2 SnS 3

International audienceThe dynamic electrical conduction in the bulk ternary semiconductor compound Cu2SnS3 is studied for the first time in the high temperature range from 300 °C to 440 °C in the frequency range 1 kHz–1 MHz. New activation energy for conduction mechanism is obtained and its frequency dependence is analyzed. The Cole–Cole representation is almost half circular indicating a single contribution to total electrical conduction through the material. The activation energy for the mean relaxation process, obtained separately from the analysis of imaginary part Z″ of complex impedance Z* and from the equivalent electric circuit, is estimated to be (942 +74). The correlated barrier hopping model is considered to analyze the experimental data. The results are compared with those obtained previously in low temperature range

Modeling and experimental investigation of the close-spaced vapor transport process for the growth of CuIn(S 0,4 Se 0,6 ) 2 thin films

International audienceThis paper reports the prediction of optimal conditions to grow good quality crystalline thin films using the Close-Spaced Vapor Transport process. A new configuration of the horizontal reactor is used and presented. A thermodynamic model is proposed for the Cu-In-S-Se-I system to describe the deposition of CuIn(S0,4Se0,6)2(CISS) compound. The simulation was performed using the SOLGASMIX software which gives the composition of the chemical system at the thermodynamic equilibrium. The model is based on the minimization of the Gibbs energy of the defined chemical system. The present study has allowed us to determine the influence of the source temperature (TS) and iodine pressure (PI2) on the growth of CISS thin films. The different compounds of the solid phase were predicted for various TS and PI2 values. The conditions of stoichiometric and quasi-stoichiometric deposition are 475 ≤ TS ≤ 525 °C and PI2 ≤ 3 kPa. Some deduced conditions from the theoretical prediction were tested experimentally. The CISS samples grown have been analyzed by X-ray diffraction and scanning electron microscope. The thin films, deposited in optimal conditions, are stoichiometric

Analysis of electrical conduction mechanism in the high temperature range of the nanostructured photoabsorber Cu 2 SnS 3

International audienceThe dynamic electrical conduction in the bulk ternary semiconductor compound Cu2SnS3 is studied for the first time in the high temperature range from 300 °C to 440 °C in the frequency range 1 kHz–1 MHz. New activation energy for conduction mechanism is obtained and its frequency dependence is analyzed. The Cole–Cole representation is almost half circular indicating a single contribution to total electrical conduction through the material. The activation energy for the mean relaxation process, obtained separately from the analysis of imaginary part Z″ of complex impedance Z* and from the equivalent electric circuit, is estimated to be (942 +74). The correlated barrier hopping model is considered to analyze the experimental data. The results are compared with those obtained previously in low temperature range

A new irrigation priority index based on remote sensing data for assessing the networks irrigation scheduling

Irrigation scheduling has become an important tool that significantly influences growth, development and production of crops, especially in arid and semi-arid regions of the South Mediterranean. In these regions, most of the irrigation scheduling of the gravity irrigation networks are not optimized in terms of timing and water quantity. In this paper, we present a way of characterizing the irrigation distribution by the extensively used irrigation systems through a new irrigation index: the "irrigation priority index" (IPI). This normalized indicator takes into account the water stress coefficient and the time of irrigation with regard to the duration of an irrigation round. The IPI ranges between -1 and 1 and decreases with irrigation priority. The IPI was used to evaluate the actual irrigation scheduling in an irrigated perimeter of 2800 ha of Tensift Al Haouz plain close to Marrakech in Morocco during the 2002-2003 winter wheat season. The obtained results showed that about 32% of the R3 zone plots receive late irrigation, when the stress was maximum (IPI less than -0.3). The sensitivity of grain yield to the IPI values was evaluated on a data set of wheat yields acquired on the 2008-2009 season. The spatial yield was simply calculated using a linear relationship between wheat yields and the spatial accumulated NDVI (Normalized Difference Vegetation Index) of the last 10 days of March (R-2 = 0.84). The result showed a clear relationship between grain yield and [PI. Indeed, with significantly positive IPI10.37, 0.63], production ranged from 3.8 to 4.7 t/ha, whereas, it was less than 2.6 t/ha when the IPI values are ranged from -0.52 to -0.16

Dielectric and modulus analysis of the photoabsorber Cu2SnS3

International audienc