Clays are a constituent of the earth. As a result, the discovery and traditional use of clays in construction and pottery worldwide dates back to antiquity. Guinea has several deposits of clay minerals whose chemical ...Clays are a constituent of the earth. As a result, the discovery and traditional use of clays in construction and pottery worldwide dates back to antiquity. Guinea has several deposits of clay minerals whose chemical and mineralogical compositions have been little studied. Despite lacking of scientific data on these clay minerals, they are used today in pottery and habitat construction. As a step towards promoting the use of clay materials in Guinea, we conducted a study of the physicochemical and mineralogical properties of three natural clays from Kakan in the Republic of Guinea (AKKB, AKKE, AKKO) used in habitat construction. The aims of this work were to better understand their properties, but above all to be able to act on them to improve and broaden their applications, which until now have been limited to construction. These clays were studied by X-ray diffraction (XRD), X-ray fluorescence spectrometry (XRF), moisture content (%W), laser granulometry, Atterberg limits, specific surface area, infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), thermogravimetric analysis and differential thermal analysis (TGA/DTA). These analyses revealed that the main clay minerals present in our samples are kaolinite, illite and, montmorillonite, with the addition of impurities, the most abundant of which is quartz.展开更多
The article develops coordinate-invariant methods to calculate reflection and refraction of plane monochromatic waves at the plane boundary between two isotropic and an isotropic and an anisotropic medium. The vectori...The article develops coordinate-invariant methods to calculate reflection and refraction of plane monochromatic waves at the plane boundary between two isotropic and an isotropic and an anisotropic medium. The vectorial wave equation for the electric field is used to determine polarization vectors to known refraction vectors and this is applied to uniaxial media. Then it is shortly shown how the boundary conditions can be derived using the Heaviside step function and its derivatives which are the delta function and its derivatives. As preparation to the anisotropic case, there are calculated in coordinate-invariant way the amplitude relations for the reflection and refraction between two isotropic media and then in analogous way, the case of reflection and refraction between an isotropic and an anisotropic medium. This is then specialized for perpendicular incidence. It is shown that negative refraction such as discussed in last twenty-five years is impossible.展开更多
Energy dissipation is one of the most important properties of granular gas, which makes Its behavior dltterent trom that of molecular gas. In this work we report our investigations on the freely-cooling evolution of g...Energy dissipation is one of the most important properties of granular gas, which makes Its behavior dltterent trom that of molecular gas. In this work we report our investigations on the freely-cooling evolution of granular gas under microgravity in a drop tower experiment, and also conduct the molecular dynamics （MD） simulation for comparison. While our experimental and simulation results support Haff＇s law that the kinetic energy dissipates with time t as E（t） （1 ＋ t/v） 2, we modify ~＂ by taking into account the friction dissipation during collisions, and study the effects of number density and particle size on the collision frequency. From the standard deviation of the measured velocity distributions we also verify the energy dissipation law, which is in agreement with Haff＇s kinetic energy dissipation.展开更多
In this paper we present a new version of Chen＇s system： a piecewise linear （PWL） Chert system of fractional-order. Via a sigmoid-like function, the discontinuous system is transformed into a continuous system. By...In this paper we present a new version of Chen＇s system： a piecewise linear （PWL） Chert system of fractional-order. Via a sigmoid-like function, the discontinuous system is transformed into a continuous system. By numerical simulations, we reveal chaotic behaviors and also multistability, i.e., the existence of small pararheter windows where, for some fixed bifurcation parameter and depending on initial conditions, coexistence of stable attractors and chaotic attractors is possible. Moreover, we show that by using an algorithm to switch the bifurcation parameter, the stable attractors can be numerically approximated.展开更多
This article contributes to a meaningful interpretation of results gathered by in-situ measurements of sonic velocity, electrical conductivity and the change of temperature during setting and curing of LC refractory c...This article contributes to a meaningful interpretation of results gathered by in-situ measurements of sonic velocity, electrical conductivity and the change of temperature during setting and curing of LC refractory castables. All said monitoring techniques are well known in the refractory community and are well documented in the literature. However, the time dependent changes of the said properties are not well correlated to mineralogical and in consequence technological changes of the material during setting and curing. The basic interest of refractory users of course is to define the time at which the installation or the pre-shape construction element can be demoulded. This is in principle possible with the methods listed above. However, after water addition the time de- pendent changes of sonic velocity, electrical conductivity and temperature are diverse as there are possible combi- nations of cements, microfines and surface-active additives. In further the ambient conditions, temperature and relative humidity have a strong influence on these properties and this does not only mean a simple time-shift. Up to now the results are more confusing than helpful to determine the best time for demoulding pre-shapes and refractory linings. Recent research at Koblenz University of Applied Science contributes to a deeper understanding of the setting behaviour, because besides the physical evolution of the said parameters the time dependent formation of hydrate phases is also investigated by means of gravi-metric method. The proposed presentation will show detailed insights in the evolution of refractory castables during setting and curing.展开更多
BACKGROUND Hip fractures are the most common reason for inpatient orthopaedic trauma admission.Urgent surgical intervention for hip fractures has remained a clinical priority throughout the coronavirus disease 2019(CO...BACKGROUND Hip fractures are the most common reason for inpatient orthopaedic trauma admission.Urgent surgical intervention for hip fractures has remained a clinical priority throughout the coronavirus disease 2019(COVID-19)pandemic.Despite this,there is a paucity of clinical guidance addressing the informed consent process for hip fracture surgery in COVID-19 positive patients.This is of paramount medicolegal importance in a high-risk patient population.AIM To quantify the additional perioperative risks for COVID-19 positive patients undergoing hip fracture surgery and provide clinicians with an evidence-based framework to establish an informed consent process.METHODS Two hundred and fifty nine consecutive patients undergoing surgical intervention for hip fractures in four hospitals in the United Kingdom were recruited.51 patients were confirmed positive for COVID-19.Predefined outcomes were analyzed over a 30-d postoperative period.COVID-19 positive and COVID-19 negative patients were compared after adjustment for confounding factors.RESULTS COVID-19 positive patients had more intensive care admissions(27%vs 5%,P<0.001),longer inpatient stays(median 23 d vs 9 d,P<0.001)and a higher 30-d mortality(29%vs 10%,P=0.001)than COVID-19 negative patients.Postoperative complications were evident in 74.5%of COVID-19 positive patients.35.3%of COVID-19 positive patients suffered postoperative lower respiratory tract infections with 13.7%developing acute respiratory distress syndrome(ARDS)and 9.8%experiencing symptomatic thromboembolic events.CONCLUSION The COVID-19 pandemic has created uncertainty in the medical community worldwide and poses unique challenges in providing informed consent for surgery.COVID-19 positive patients undergoing hip fracture surgery should be consented for the additional risk of postoperative complications(including lower respiratory tract infection,ARDS,deep vein thrombosis and pulmonary embolism),increased requirement for intensive care admission,longer inpatient stay and higher risk of mortality.Further,clinicians must be transparent about the potential for unknown risks as research into the long-term surgical outcomes of COVID-19 positive patients continues to evolve.展开更多
Evidence⁃based practices of public health will benefit from quantification of passive physical activity assessment.This study aims to investigate the reliability of marker⁃free system(MFS)such as Microsoft Kinect in m...Evidence⁃based practices of public health will benefit from quantification of passive physical activity assessment.This study aims to investigate the reliability of marker⁃free system(MFS)such as Microsoft Kinect in measuring upper extremity motion from different angles.Ten healthy participants performed elbow and shoulder extension/flexion along frontal and median anatomical planes for ten pace⁃controlled repetitions,during which the spatiotemporal positions of upper extremity joints were concurrently recorded by two sensors from 0°and 45°viewing angles.Reliability between the two sensors were evaluated using Pearson correlation coefficient,intra⁃class correlation coefficients,and 95%limits of agreement and coefficient of variation.Worse reliability was observed when possibility of occlusion was higher.However,better reliability was found when longer observation interval(10 s)was used as elementary measuring unit than shorter observation interval(2 s).The overall angular reliability of activity as displacement or changes in angle was not satisfactory.The results are expected to inform the industry for the extension of MFS to clinic applications.展开更多
<b><span style="font-family:;" "="">Introduction<span>:</span></span></b><span><i><span style="font-family:;" "=""&g...<b><span style="font-family:;" "="">Introduction<span>:</span></span></b><span><i><span style="font-family:;" "=""> Pergularia tomentosa</span></i></span><span><span style="font-family:;" "=""> is a saharan spontaneous plant belonging to <i>Asclepiadacea </i>family. It has several medicinal properties and uses in the human food as an auxiliary in cheese-making. The purpose of this study is the extraction of the coagulant enzymatic system (C.E.S) from the plant dried leaves and its use in the preparation of fresh cheese. <b>Materials & Methods</b></span></span><span><b><span style="font-family:;" "="">: </span></b></span><span><span style="font-family:;" "="">The determination of the coagulant activity was carried out on a skimmed</span></span><span><span style="font-family:;" "=""> milk <span>powder by Berridge’s method. Cow’s milk used for coagulant strength</span> deter<span>mination and cheese-making. Proteolytic activity</span></span></span><span><span style="font-family:;" "="">. </span></span><span><span style="font-family:;" "="">The chemical </span></span><span><span style="font-family:;" "="">determinations <span>of raw milk were carried out according to AFNOR analysis methods. A</span> descriptive sensory evaluation was performed to determine the organoleptic pro<span>perties of the produced cheese. The proteolytic activity was determined b</span>y measuring the aspartyl-protease units. <b>Results:</b> The main results of the phy<span>sico-chemical characterization show that its coagulant activity (R.U mL<sup>-1</sup>)</span> was 97.19 ± 4.67, coagulant strength (SU) was 230.05 ± 0.37, proteolytic activity (μg<span style="font-family:Verdana, Helvetica, Arial;white-space:normal;background-color:#FFFFFF;">·</span>mL<sup>-1</sup>) was 0.33 ± 0.04 and coagulant activity/proteolytic activity ratio was <span>294.51. For the cheese made, it has presented the following results</span></span></span><span><span style="font-family:;" "=""> </span></span><span><span style="font-family:;" "="">as %</span></span><span><span style="font-family:;" "=""> (g/100g): <span>titrable acidity 0.80 ± 0.005, total dry extract 30.48 ± 1.490, fat 2</span></span></span><span><span style="font-family:;" "="">.</span></span><span><span style="font-family:;" "="">32 ± 0.02, fresh </span></span><span><span style="font-family:;" "="">yield 11.5 ± 0</span></span><span><span style="font-family:;" "="">.</span></span><span><span style="font-family:;" "="">09, dry yield 30.06 ± 0.05. Moreover, sensory analysis results<span> showed that fresh cheese prepared from <i>Pergularia tomentosa</i> dried</span> <span>leaves diluted enzymatic extract filtrate was characterized by whitish color</span><span>, smooth texture, with acceptable and satisfying lactic taste. <b>Conclusion:</b> The plant enzymatic system studied could be added to the list of plant rennet substitutes and, thus, contribute</span></span></span><span><span style="font-family:;" "="">s</span></span><span><span style="font-family:;" "=""> to the manufacture of enzymatic coagula</span></span><span><span style="font-family:;" "="">tion cheese.</span></span><span></span><span style="font-family:;" "=""></span>展开更多
A combined analysis of geochemical and production data of 39 wells of the Los Azufres (Mexico) geothermal field (227.4 MWe) over time was developed to investigate the exploitation-related processes for 2003-2011. In t...A combined analysis of geochemical and production data of 39 wells of the Los Azufres (Mexico) geothermal field (227.4 MWe) over time was developed to investigate the exploitation-related processes for 2003-2011. In the south zone, important effects of reinjection were observed through Cl increases in some wells (up to 8000 mg/kg) while in wells with significant boiling, Cl has decreased. In most of the north zone wells, the variations in gas data indicated boiling and condensation of a highly gas-depleted brine, which seems to consist of reinjection fluids. It is suggested that this process maintains the production in the zone relatively stable. The main reservoir exploitation-related processes found were: 1) production of reinjection returns;for this, it was possible to distinguish a) wells that produce liquid and steam from injection, and b) wells that produce steam from injection and sometimes condensed steam from injection;2) boiling: two types of boiling were identified: a) boiling with steam gain, and b) boiling with steam loss. The results indicated that an effective reservoir recharge occurs since very moderate production declining rates were found.展开更多
Background: We aimed to describe addictive behaviours and identify risk factors for addiction among students in their first year of university, which is known to represent a stressful situation conducive to the emerge...Background: We aimed to describe addictive behaviours and identify risk factors for addiction among students in their first year of university, which is known to represent a stressful situation conducive to the emergence of addictive behaviours. Methods: Ongoing cross-sectional survey among first-year students of the University of Reims Champagne-Ardenne (France). The first 16 months of the survey, which is due to run for 5 years, are analysed here. A self-report questionnaire was proposed to all first-year students during their mandatory preventive medicine consultation. The questionnaire kit comprised validated questionnaires evaluating addiction to alcohol, tobacco, cannabis, cocaine, amphetamines, solvents, tranquillizers, hallucinogens, opiates, other drugs, internet, and gambling or games of chance. Results: In total, 1139 students were included in this analysis;participation rate was 94% among all those invited to participate. Average age was 19 ± 1 years, male to female sex ratio was 0.54. Among respondents, 18% were at risk of addiction to alcohol, 2.3% were addicted;19.6% were smokers, and 5.5% were dependent. Cannabis was the most frequently used illicit substance, with 4.8% of students at risk, and 2 subjects addicted. For the internet, 11.6% of subjects were at risk, and 1.4% were addicted. By logistic regression, students receiving grants or whose parents have a low socio-professional category were at less risk of addiction to alcohol. We also found that students at risk were less likely to accept treatment. Conclusion: These initial findings show that certain addictive behaviours are particularly prevalent among first-year students, with identifiable risk factors or protective factors, thereby opening avenues for preventive and therapeutic measures.展开更多
In the storage ring RF system of Shanghai Synchrotron Radiation Facility,the clock distribution and the local oscillator are two parts of the digital low level radio frequency hardware board.In this paper,we designed ...In the storage ring RF system of Shanghai Synchrotron Radiation Facility,the clock distribution and the local oscillator are two parts of the digital low level radio frequency hardware board.In this paper,we designed and produced the clock distribution and the local oscillator board using the AD9858 and AD9510 chips.The results show that the phase noise of the local oscillator signal is lower than 100dBc/Hz with 50 kHz offset.展开更多
The effects of exercise on decision-making performance have been studied using a wide variety of cognitive tasks and exercise interventions. Although the current literature supports a beneficial influence of acute exe...The effects of exercise on decision-making performance have been studied using a wide variety of cognitive tasks and exercise interventions. Although the current literature supports a beneficial influence of acute exercise on cognitive performance, the mechanisms underlying this phenomenon have not yet been elucidated. We review studies that used single-pulse transcranial magnetic stimulation （TMS） to probe the excitability of motor structures during whole-body exercise and present a framework to account for the facilitating effects of acute exercise on motor processes. Recent results suggest that, even in the absence of fatigue, the increase in corticospinal excitability classically reported during submaximal and exhausting exercises may be accompanied by a reduction in intracortical inhibition. We propose that reduced intracortical inhibition elicits an adaptive central mechanism that counteracts the progressive reduction in muscle responsiveness caused by peripheral fatigue. Such a reduction would render the motor cortex more sensitive to upstream influences, thus causing increased corticospinal excitability. Furthermore, reduction of intracortical inhibition may account for the more efficient descending drive and for the improvement of reaction time performance during exercise. The adaptive modulation in intracortical inhibition could be implemented through a general increase in reticular activation that would further account for enhanced sensory sensitivity.展开更多
Objective:To investigate the total phenolics,flavonoids and tannins content and the in vitro antioxidant activities of methanolic extracts of six wild Mentha species which are Mentha aquatica,Mentha arvensis,Mentha pi...Objective:To investigate the total phenolics,flavonoids and tannins content and the in vitro antioxidant activities of methanolic extracts of six wild Mentha species which are Mentha aquatica,Mentha arvensis,Mentha piperita,Mentha pulegium,Mentha rotundifolia and Mentha villosa.Methods:The Folin–Ciocalteu method was used to determine the total phenols content while flavonoids were estimated according to the aluminum chloride colorimetric method.To evaluate tannins content,vanillin and HCl were added to methanolic extracts.The antioxidant potential was measured by 1,1-diphenyl-2-picrylhydrazyl radical scavenging,ferrous ion chelating and the inhibition of b-carotene bleaching assays.Results:The methanol extracts of Algerian mints were rich in phenolic compounds and exhibited powerful antioxidant activity ranging from 7.5 mg/mL to 44.66 mg/mL,which varied significantly among species.Mentha aquatica stood out with efficient antioxidant ability which was correlated to the high total phenolics content,followed by Mentha arvensis and Mentha piperita with very close values,comparing to Mentha pulegium,Mentha rotundifolia and Mentha villosa with lowest values.Conclusions:These results show that methanolic extracts of Mentha species from Algeria have a great potential of polyphenols which can be used as a natural food preservative and antioxidant source.展开更多
The influence of in-port ship emissions on gases and PM10 concentrations has been estimated in the port city of Calais, northern France, one of the busiest harbor in Europe, with numerous rotations of ferries or roll-...The influence of in-port ship emissions on gases and PM10 concentrations has been estimated in the port city of Calais, northern France, one of the busiest harbor in Europe, with numerous rotations of ferries or roll-on/roll-off cargo in average per day. NOx, SO2, O3 and PM10 concentrations were continuously measured over a three-month period, as well as real-time particle size distribution. A rural site located at Cape Gris-Nez, 20 km from Calais, was considered to deduce intrinsic contribution of ship emissions at the harbor city. The average concentrations of the studied species as well as the pattern of the conditional bivariate probability function at the two sites evidenced that in-port shipping, especially during the maneuvering operations, has an important influence on the NOx and SO2 concentrations. The impact of shipping in the harbor of Calais on average concentrations was estimated to 5l% for SO2, 35% for NO, 15% for NO2 and 2% for PM10 in the studied period. Concentration peaks of SO2 and NOx associated with an 03 depletion appeared synchronized with departures and arrivals of ferries. For winds blowing from the harbor, when compared to the background level, the number of particles appeared 10 times higher, with the highest differences in the 30-67 nm and the 109-167 nm size ranges. The average impact of in-port ships on PM10 concentrations was estimated to ＋28.9 μg/m^3 and concerned mainly the PM1 size fraction （40%）. Punctually, PM10 can potentially reach a concentration value close to 100μg/m^3.展开更多
In recent years,hard carbon materials have gained significant interest as anode materials for Na-ion batteries.Biomass waste is considered one of the most interesting,renewable,available,and cost-effective precursor t...In recent years,hard carbon materials have gained significant interest as anode materials for Na-ion batteries.Biomass waste is considered one of the most interesting,renewable,available,and cost-effective precursor to obtain hard carbon(HC);however,HC properties must be finely tuned to achieve performance comparable to those provided by Li-ion batteries.In this work,three biomass wastes(coconut shells,walnut shells,and corn silk) were evaluated as potential precursors for HC preparation involving a pyrolysis process and subsequent acid washing to remove the inorganic impurities.All obtained materials exhibited low and similar specific surface areas(<10 m^(2)·g^(-1)), but they presented different structures and surface functionalities.The walnut shell HC possessed a lower amount of inorganic impurities and oxygen-based functional groups compared to the coconut shell and corn silk HCs,leading to higher initial coulombic efficiency(iCE).The structural organization was higher in the case of the walnut shell HC,while the corn silk HC revealed a heterogeneous structure combining both highly disordered carbon and localized graphitized domains.All HCs delivered high initial reversible capacities between 293 and 315 mAh g^(-1) at 50 mA g^(-1) current rate,which remained rather stable during long-term cycling.The best capacity(293 mAh g^(-1) after 100 charge/discharge cycles) and highest capacity retention(93%) was achieved in walnut HCs in half-cells,which could be associated with its higher sp2 C content,better organized structure,and fewer impurities.An "adsorption-insertion" Na storage mechanism is suggested based on several techniques.The walnut HCs exhibited an attractive energy density of 279 Wh/kg when tested in full cells.展开更多
The carrier-envelope phase(CEP)φ_(0)is one of the key parameters in the generation of isolated attosecond pulses.In particular,“cosine”pulses(φ_(0)=0)are best suited for generation of single attosecond pulses in a...The carrier-envelope phase(CEP)φ_(0)is one of the key parameters in the generation of isolated attosecond pulses.In particular,“cosine”pulses(φ_(0)=0)are best suited for generation of single attosecond pulses in atomic media.Such“cosine”pulses have the peak of the most intense cycle aligned with the peak of the pulse envelope,and therefore have the highest contrast between the peak intensity and the neighboring cycles.In this paper,the dynamics of single attosecond pulse generation from a relativistically oscillating plasma mirror is investigated.We use an elementary analytical model as well as particle-in-cell simulations to study few-cycle attosecond pulses.We find that the phase of the field driving the surface oscillations depends on the plasma density and preplasma scale length.This leads us to a counterintuitive conclusion:for the case of normal incidence and a sharp plasma-vacuum boundary,the CEP required for the generation of a single attosecond pulse phase is closer toφ_(0)=π/2(a“sine”pulse),with the exact value depending on the plasma parameters.展开更多
This special issue consists of 12 invited reviews on the frontier areas of as- tronomy and astrophysics, and is aimed at a timely, in-depth evaluation of the current status and key progress, with suggestions for futur...This special issue consists of 12 invited reviews on the frontier areas of as- tronomy and astrophysics, and is aimed at a timely, in-depth evaluation of the current status and key progress, with suggestions for future directions. This special issue is particularly dedicated to the IAU XXVIIIth General Assembly （GA） and is complementary to the IAU GA Invited Discourses during the conference.展开更多
Purpose: The present studied was performed in order to investigate the drug resistance of different non-lactose fermenting gram negative bacteria from clinical isolates. The bacteria were morphologically characterized...Purpose: The present studied was performed in order to investigate the drug resistance of different non-lactose fermenting gram negative bacteria from clinical isolates. The bacteria were morphologically characterized through culturing and gram staining techniques were used for the identification of different bacterial strains. Methods: A total of 324 samples were collected from patients, after they were diagnosed by physicians at different hospitals at district Peshawar. Samples were morphologically identified by blood agar, MacConkey agar and Eosine Methylene Blue, identified by gram staining techniques. Modified Kirby-Bauer Disc diffusion method was used to test the in-vitro susceptibility of the identified isolates to different antibiotics. Results: The non-lactose fermenting gram negative bacteria were isolated from samples of blood (33.30%), pus/ wound (33.30%), urine (23.30%) and from ascetic/pleural fluids (10.20%). The study revealed that Pseudomonas aeroginosa showed high resistance against Gentamicin (74%) and Aztreonam (74%), followed by Ciprofloxacin (59.20%) and Amikacin (33.30). Tazocin was active as low resistance (18.50%) is shown. More resistance was seen in Morganella morganii against Aztreonam (77.7%) followed by Gentamicin (62.90%), Ciprofloxacin (40.70%). Tazocin show low resistance (3.70%). Multidrug resistant Proteus mirabillis was highly resistance to Gentamicin (66.60%), followed by Aztreonam (62.90%), Amikacin (55.50%), Ciprofloxacin (40.20%) and low resistance to Tazocin was (22.20%). Salmonella typhi demonstrated high resistance against Amikacin (62.90%), followed by Aztreonam (48.10%), Tazocin (40.70%). Gentamicin showed low resistance (29.60%), and hence it is more active against S. typhi. Conclusions: It can be concluded from the present study that different species of non-lactose fermenting gram negative bacteria have shown a different resistivity pattern. This study is a gate way for better and suitable management strategy for the infections caused by non-Lactose fermenting bacteria in the sampling region.展开更多
Enhanced mobile broadband(e MBB) is one of the key use-cases for the development of the new standard 5G New Radio for thenext generation of mobile wireless networks. Large-scale antenna arrays, a.k.a. massive multiple...Enhanced mobile broadband(e MBB) is one of the key use-cases for the development of the new standard 5G New Radio for thenext generation of mobile wireless networks. Large-scale antenna arrays, a.k.a. massive multiple-input multiple-output(MIMO), theusage of carrier frequencies in the range 10-100 GHz, the so-called millimeter wave(mm-Wave) band, and the network densifica-tion with the introduction of small-sized cells are the three technologies that will permit implementing e MBB services and realiz-ing the Gbit/s mobile wireless experience. This paper is focused on the massive MIMO technology. Initially conceived for conven-tional cellular frequencies in the sub-6 GHz range(μ-Wave), the massive MIMO concept has been then progressively extended tothe case in which mm-Wave frequencies are used. However, due to different propagation mechanisms in urban scenarios, the re-sulting MIMO channel models at μ-Wave and mm-Wave are radically different. Six key basic differences are pinpointed in thispaper, along with the implications that they have on the architecture and algorithms of the communication transceivers and on theattainable performance in terms of reliability and multiplexing capabilities.展开更多
In order to contribute to the valorisation of the clay materials of Ivory Coast in the depollution of wastewater, the physicochemical and mineralogical characterization of three clay samples taken in Agboville (AGB), ...In order to contribute to the valorisation of the clay materials of Ivory Coast in the depollution of wastewater, the physicochemical and mineralogical characterization of three clay samples taken in Agboville (AGB), Bingerville (BIN) and Katiola (KAT) was carried out. The objective of this work was to compare the properties of the clays in order to identify the one that is likely to have interesting adsorptive capacities to clean up contaminated water. These clays were studied by chemical analysis, X-ray diffraction, scanning electron microscopy and thermal analysis. In addition, their specific surface areas and cation exchange capacities were determined. The AGB clay is composed of 75.51% kaolinite, 14.20% illite and 9.26% quartz. The BIN clay contains 52.21% kaolinite, 6.23% illite, 17.50% quartz and 15.71% goethite. As for the KAT clay, it contains 48.08% kaolinite, 3.55% illite, 20.14% smectite, 6.11% quartz and 16.86% goethite. Their thermal behavior and microstructure are in agreement with their mineralogy. The measured specific surface areas and cation exchange capacities are consistent with literature values. The KAT clay has the highest specific surface and cation exchange capacity. In the light of the results obtained, the KAT clay appears to be more effective in depolluting water than the BIN and AGB clays.展开更多
文摘Clays are a constituent of the earth. As a result, the discovery and traditional use of clays in construction and pottery worldwide dates back to antiquity. Guinea has several deposits of clay minerals whose chemical and mineralogical compositions have been little studied. Despite lacking of scientific data on these clay minerals, they are used today in pottery and habitat construction. As a step towards promoting the use of clay materials in Guinea, we conducted a study of the physicochemical and mineralogical properties of three natural clays from Kakan in the Republic of Guinea (AKKB, AKKE, AKKO) used in habitat construction. The aims of this work were to better understand their properties, but above all to be able to act on them to improve and broaden their applications, which until now have been limited to construction. These clays were studied by X-ray diffraction (XRD), X-ray fluorescence spectrometry (XRF), moisture content (%W), laser granulometry, Atterberg limits, specific surface area, infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), thermogravimetric analysis and differential thermal analysis (TGA/DTA). These analyses revealed that the main clay minerals present in our samples are kaolinite, illite and, montmorillonite, with the addition of impurities, the most abundant of which is quartz.
文摘The article develops coordinate-invariant methods to calculate reflection and refraction of plane monochromatic waves at the plane boundary between two isotropic and an isotropic and an anisotropic medium. The vectorial wave equation for the electric field is used to determine polarization vectors to known refraction vectors and this is applied to uniaxial media. Then it is shortly shown how the boundary conditions can be derived using the Heaviside step function and its derivatives which are the delta function and its derivatives. As preparation to the anisotropic case, there are calculated in coordinate-invariant way the amplitude relations for the reflection and refraction between two isotropic media and then in analogous way, the case of reflection and refraction between an isotropic and an anisotropic medium. This is then specialized for perpendicular incidence. It is shown that negative refraction such as discussed in last twenty-five years is impossible.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.U1738120 and 11474326)
文摘Energy dissipation is one of the most important properties of granular gas, which makes Its behavior dltterent trom that of molecular gas. In this work we report our investigations on the freely-cooling evolution of granular gas under microgravity in a drop tower experiment, and also conduct the molecular dynamics （MD） simulation for comparison. While our experimental and simulation results support Haff＇s law that the kinetic energy dissipates with time t as E（t） （1 ＋ t/v） 2, we modify ~＂ by taking into account the friction dissipation during collisions, and study the effects of number density and particle size on the collision frequency. From the standard deviation of the measured velocity distributions we also verify the energy dissipation law, which is in agreement with Haff＇s kinetic energy dissipation.
基金funded by the European Regional Development Funding via RISC projectby CPER Region Haute Normandie France,the Australian Research Council via a Future Fellowship(FT110100896)Discovery Project(DP140100203)
文摘In this paper we present a new version of Chen＇s system： a piecewise linear （PWL） Chert system of fractional-order. Via a sigmoid-like function, the discontinuous system is transformed into a continuous system. By numerical simulations, we reveal chaotic behaviors and also multistability, i.e., the existence of small pararheter windows where, for some fixed bifurcation parameter and depending on initial conditions, coexistence of stable attractors and chaotic attractors is possible. Moreover, we show that by using an algorithm to switch the bifurcation parameter, the stable attractors can be numerically approximated.
基金German Federation of Industrial Research Associations ( AiF) for its financial support of the research project IGF-No.119 ENcarried out under the auspices of Ai F and financed within the budget of the Federal Ministry of Economics and Technology ( BMWi) through the program to promote collective industrial research (IGF)
文摘This article contributes to a meaningful interpretation of results gathered by in-situ measurements of sonic velocity, electrical conductivity and the change of temperature during setting and curing of LC refractory castables. All said monitoring techniques are well known in the refractory community and are well documented in the literature. However, the time dependent changes of the said properties are not well correlated to mineralogical and in consequence technological changes of the material during setting and curing. The basic interest of refractory users of course is to define the time at which the installation or the pre-shape construction element can be demoulded. This is in principle possible with the methods listed above. However, after water addition the time de- pendent changes of sonic velocity, electrical conductivity and temperature are diverse as there are possible combi- nations of cements, microfines and surface-active additives. In further the ambient conditions, temperature and relative humidity have a strong influence on these properties and this does not only mean a simple time-shift. Up to now the results are more confusing than helpful to determine the best time for demoulding pre-shapes and refractory linings. Recent research at Koblenz University of Applied Science contributes to a deeper understanding of the setting behaviour, because besides the physical evolution of the said parameters the time dependent formation of hydrate phases is also investigated by means of gravi-metric method. The proposed presentation will show detailed insights in the evolution of refractory castables during setting and curing.
文摘BACKGROUND Hip fractures are the most common reason for inpatient orthopaedic trauma admission.Urgent surgical intervention for hip fractures has remained a clinical priority throughout the coronavirus disease 2019(COVID-19)pandemic.Despite this,there is a paucity of clinical guidance addressing the informed consent process for hip fracture surgery in COVID-19 positive patients.This is of paramount medicolegal importance in a high-risk patient population.AIM To quantify the additional perioperative risks for COVID-19 positive patients undergoing hip fracture surgery and provide clinicians with an evidence-based framework to establish an informed consent process.METHODS Two hundred and fifty nine consecutive patients undergoing surgical intervention for hip fractures in four hospitals in the United Kingdom were recruited.51 patients were confirmed positive for COVID-19.Predefined outcomes were analyzed over a 30-d postoperative period.COVID-19 positive and COVID-19 negative patients were compared after adjustment for confounding factors.RESULTS COVID-19 positive patients had more intensive care admissions(27%vs 5%,P<0.001),longer inpatient stays(median 23 d vs 9 d,P<0.001)and a higher 30-d mortality(29%vs 10%,P=0.001)than COVID-19 negative patients.Postoperative complications were evident in 74.5%of COVID-19 positive patients.35.3%of COVID-19 positive patients suffered postoperative lower respiratory tract infections with 13.7%developing acute respiratory distress syndrome(ARDS)and 9.8%experiencing symptomatic thromboembolic events.CONCLUSION The COVID-19 pandemic has created uncertainty in the medical community worldwide and poses unique challenges in providing informed consent for surgery.COVID-19 positive patients undergoing hip fracture surgery should be consented for the additional risk of postoperative complications(including lower respiratory tract infection,ARDS,deep vein thrombosis and pulmonary embolism),increased requirement for intensive care admission,longer inpatient stay and higher risk of mortality.Further,clinicians must be transparent about the potential for unknown risks as research into the long-term surgical outcomes of COVID-19 positive patients continues to evolve.
基金Sponsored by the National Natural Science Foundation of China(Grant No.51708152)the Science and Technology Innovation Committee of Shenzhen Municipality(Grant No.JCYJ20170811155435737).
文摘Evidence⁃based practices of public health will benefit from quantification of passive physical activity assessment.This study aims to investigate the reliability of marker⁃free system(MFS)such as Microsoft Kinect in measuring upper extremity motion from different angles.Ten healthy participants performed elbow and shoulder extension/flexion along frontal and median anatomical planes for ten pace⁃controlled repetitions,during which the spatiotemporal positions of upper extremity joints were concurrently recorded by two sensors from 0°and 45°viewing angles.Reliability between the two sensors were evaluated using Pearson correlation coefficient,intra⁃class correlation coefficients,and 95%limits of agreement and coefficient of variation.Worse reliability was observed when possibility of occlusion was higher.However,better reliability was found when longer observation interval(10 s)was used as elementary measuring unit than shorter observation interval(2 s).The overall angular reliability of activity as displacement or changes in angle was not satisfactory.The results are expected to inform the industry for the extension of MFS to clinic applications.
文摘<b><span style="font-family:;" "="">Introduction<span>:</span></span></b><span><i><span style="font-family:;" "=""> Pergularia tomentosa</span></i></span><span><span style="font-family:;" "=""> is a saharan spontaneous plant belonging to <i>Asclepiadacea </i>family. It has several medicinal properties and uses in the human food as an auxiliary in cheese-making. The purpose of this study is the extraction of the coagulant enzymatic system (C.E.S) from the plant dried leaves and its use in the preparation of fresh cheese. <b>Materials & Methods</b></span></span><span><b><span style="font-family:;" "="">: </span></b></span><span><span style="font-family:;" "="">The determination of the coagulant activity was carried out on a skimmed</span></span><span><span style="font-family:;" "=""> milk <span>powder by Berridge’s method. Cow’s milk used for coagulant strength</span> deter<span>mination and cheese-making. Proteolytic activity</span></span></span><span><span style="font-family:;" "="">. </span></span><span><span style="font-family:;" "="">The chemical </span></span><span><span style="font-family:;" "="">determinations <span>of raw milk were carried out according to AFNOR analysis methods. A</span> descriptive sensory evaluation was performed to determine the organoleptic pro<span>perties of the produced cheese. The proteolytic activity was determined b</span>y measuring the aspartyl-protease units. <b>Results:</b> The main results of the phy<span>sico-chemical characterization show that its coagulant activity (R.U mL<sup>-1</sup>)</span> was 97.19 ± 4.67, coagulant strength (SU) was 230.05 ± 0.37, proteolytic activity (μg<span style="font-family:Verdana, Helvetica, Arial;white-space:normal;background-color:#FFFFFF;">·</span>mL<sup>-1</sup>) was 0.33 ± 0.04 and coagulant activity/proteolytic activity ratio was <span>294.51. For the cheese made, it has presented the following results</span></span></span><span><span style="font-family:;" "=""> </span></span><span><span style="font-family:;" "="">as %</span></span><span><span style="font-family:;" "=""> (g/100g): <span>titrable acidity 0.80 ± 0.005, total dry extract 30.48 ± 1.490, fat 2</span></span></span><span><span style="font-family:;" "="">.</span></span><span><span style="font-family:;" "="">32 ± 0.02, fresh </span></span><span><span style="font-family:;" "="">yield 11.5 ± 0</span></span><span><span style="font-family:;" "="">.</span></span><span><span style="font-family:;" "="">09, dry yield 30.06 ± 0.05. Moreover, sensory analysis results<span> showed that fresh cheese prepared from <i>Pergularia tomentosa</i> dried</span> <span>leaves diluted enzymatic extract filtrate was characterized by whitish color</span><span>, smooth texture, with acceptable and satisfying lactic taste. <b>Conclusion:</b> The plant enzymatic system studied could be added to the list of plant rennet substitutes and, thus, contribute</span></span></span><span><span style="font-family:;" "="">s</span></span><span><span style="font-family:;" "=""> to the manufacture of enzymatic coagula</span></span><span><span style="font-family:;" "="">tion cheese.</span></span><span></span><span style="font-family:;" "=""></span>
文摘A combined analysis of geochemical and production data of 39 wells of the Los Azufres (Mexico) geothermal field (227.4 MWe) over time was developed to investigate the exploitation-related processes for 2003-2011. In the south zone, important effects of reinjection were observed through Cl increases in some wells (up to 8000 mg/kg) while in wells with significant boiling, Cl has decreased. In most of the north zone wells, the variations in gas data indicated boiling and condensation of a highly gas-depleted brine, which seems to consist of reinjection fluids. It is suggested that this process maintains the production in the zone relatively stable. The main reservoir exploitation-related processes found were: 1) production of reinjection returns;for this, it was possible to distinguish a) wells that produce liquid and steam from injection, and b) wells that produce steam from injection and sometimes condensed steam from injection;2) boiling: two types of boiling were identified: a) boiling with steam gain, and b) boiling with steam loss. The results indicated that an effective reservoir recharge occurs since very moderate production declining rates were found.
文摘Background: We aimed to describe addictive behaviours and identify risk factors for addiction among students in their first year of university, which is known to represent a stressful situation conducive to the emergence of addictive behaviours. Methods: Ongoing cross-sectional survey among first-year students of the University of Reims Champagne-Ardenne (France). The first 16 months of the survey, which is due to run for 5 years, are analysed here. A self-report questionnaire was proposed to all first-year students during their mandatory preventive medicine consultation. The questionnaire kit comprised validated questionnaires evaluating addiction to alcohol, tobacco, cannabis, cocaine, amphetamines, solvents, tranquillizers, hallucinogens, opiates, other drugs, internet, and gambling or games of chance. Results: In total, 1139 students were included in this analysis;participation rate was 94% among all those invited to participate. Average age was 19 ± 1 years, male to female sex ratio was 0.54. Among respondents, 18% were at risk of addiction to alcohol, 2.3% were addicted;19.6% were smokers, and 5.5% were dependent. Cannabis was the most frequently used illicit substance, with 4.8% of students at risk, and 2 subjects addicted. For the internet, 11.6% of subjects were at risk, and 1.4% were addicted. By logistic regression, students receiving grants or whose parents have a low socio-professional category were at less risk of addiction to alcohol. We also found that students at risk were less likely to accept treatment. Conclusion: These initial findings show that certain addictive behaviours are particularly prevalent among first-year students, with identifiable risk factors or protective factors, thereby opening avenues for preventive and therapeutic measures.
基金Supported by Shanghai Synchrotron Radiation Facility
文摘In the storage ring RF system of Shanghai Synchrotron Radiation Facility,the clock distribution and the local oscillator are two parts of the digital low level radio frequency hardware board.In this paper,we designed and produced the clock distribution and the local oscillator board using the AD9858 and AD9510 chips.The results show that the phase noise of the local oscillator signal is lower than 100dBc/Hz with 50 kHz offset.
文摘The effects of exercise on decision-making performance have been studied using a wide variety of cognitive tasks and exercise interventions. Although the current literature supports a beneficial influence of acute exercise on cognitive performance, the mechanisms underlying this phenomenon have not yet been elucidated. We review studies that used single-pulse transcranial magnetic stimulation （TMS） to probe the excitability of motor structures during whole-body exercise and present a framework to account for the facilitating effects of acute exercise on motor processes. Recent results suggest that, even in the absence of fatigue, the increase in corticospinal excitability classically reported during submaximal and exhausting exercises may be accompanied by a reduction in intracortical inhibition. We propose that reduced intracortical inhibition elicits an adaptive central mechanism that counteracts the progressive reduction in muscle responsiveness caused by peripheral fatigue. Such a reduction would render the motor cortex more sensitive to upstream influences, thus causing increased corticospinal excitability. Furthermore, reduction of intracortical inhibition may account for the more efficient descending drive and for the improvement of reaction time performance during exercise. The adaptive modulation in intracortical inhibition could be implemented through a general increase in reticular activation that would further account for enhanced sensory sensitivity.
基金Supported by Ministry of Higher Education Scientific Research and Technology,Algeria(Grant No.F03120130013/2014)
文摘Objective:To investigate the total phenolics,flavonoids and tannins content and the in vitro antioxidant activities of methanolic extracts of six wild Mentha species which are Mentha aquatica,Mentha arvensis,Mentha piperita,Mentha pulegium,Mentha rotundifolia and Mentha villosa.Methods:The Folin–Ciocalteu method was used to determine the total phenols content while flavonoids were estimated according to the aluminum chloride colorimetric method.To evaluate tannins content,vanillin and HCl were added to methanolic extracts.The antioxidant potential was measured by 1,1-diphenyl-2-picrylhydrazyl radical scavenging,ferrous ion chelating and the inhibition of b-carotene bleaching assays.Results:The methanol extracts of Algerian mints were rich in phenolic compounds and exhibited powerful antioxidant activity ranging from 7.5 mg/mL to 44.66 mg/mL,which varied significantly among species.Mentha aquatica stood out with efficient antioxidant ability which was correlated to the high total phenolics content,followed by Mentha arvensis and Mentha piperita with very close values,comparing to Mentha pulegium,Mentha rotundifolia and Mentha villosa with lowest values.Conclusions:These results show that methanolic extracts of Mentha species from Algeria have a great potential of polyphenols which can be used as a natural food preservative and antioxidant source.
基金the Atmosphere Protection Plan funded by the Environment, Planning and Housing Regional Agency (Nord-Pas-de-Calais)The “Unité de Chimie Environnementale et Interactions sur le Vivant”, UCEIV EA4492participates in the CLIMIBIO project, which is financially supported by the Hauts-de-France Region Council, the Ministry of Higher Education and Research, the European Regional Development Funds
文摘The influence of in-port ship emissions on gases and PM10 concentrations has been estimated in the port city of Calais, northern France, one of the busiest harbor in Europe, with numerous rotations of ferries or roll-on/roll-off cargo in average per day. NOx, SO2, O3 and PM10 concentrations were continuously measured over a three-month period, as well as real-time particle size distribution. A rural site located at Cape Gris-Nez, 20 km from Calais, was considered to deduce intrinsic contribution of ship emissions at the harbor city. The average concentrations of the studied species as well as the pattern of the conditional bivariate probability function at the two sites evidenced that in-port shipping, especially during the maneuvering operations, has an important influence on the NOx and SO2 concentrations. The impact of shipping in the harbor of Calais on average concentrations was estimated to 5l% for SO2, 35% for NO, 15% for NO2 and 2% for PM10 in the studied period. Concentration peaks of SO2 and NOx associated with an 03 depletion appeared synchronized with departures and arrivals of ferries. For winds blowing from the harbor, when compared to the background level, the number of particles appeared 10 times higher, with the highest differences in the 30-67 nm and the 109-167 nm size ranges. The average impact of in-port ships on PM10 concentrations was estimated to ＋28.9 μg/m^3 and concerned mainly the PM1 size fraction （40%）. Punctually, PM10 can potentially reach a concentration value close to 100μg/m^3.
基金financial support from the European Union’s Horizon2020 Program(project NAIADEScall:LCE10-2014,Contract no.646433)。
文摘In recent years,hard carbon materials have gained significant interest as anode materials for Na-ion batteries.Biomass waste is considered one of the most interesting,renewable,available,and cost-effective precursor to obtain hard carbon(HC);however,HC properties must be finely tuned to achieve performance comparable to those provided by Li-ion batteries.In this work,three biomass wastes(coconut shells,walnut shells,and corn silk) were evaluated as potential precursors for HC preparation involving a pyrolysis process and subsequent acid washing to remove the inorganic impurities.All obtained materials exhibited low and similar specific surface areas(<10 m^(2)·g^(-1)), but they presented different structures and surface functionalities.The walnut shell HC possessed a lower amount of inorganic impurities and oxygen-based functional groups compared to the coconut shell and corn silk HCs,leading to higher initial coulombic efficiency(iCE).The structural organization was higher in the case of the walnut shell HC,while the corn silk HC revealed a heterogeneous structure combining both highly disordered carbon and localized graphitized domains.All HCs delivered high initial reversible capacities between 293 and 315 mAh g^(-1) at 50 mA g^(-1) current rate,which remained rather stable during long-term cycling.The best capacity(293 mAh g^(-1) after 100 charge/discharge cycles) and highest capacity retention(93%) was achieved in walnut HCs in half-cells,which could be associated with its higher sp2 C content,better organized structure,and fewer impurities.An "adsorption-insertion" Na storage mechanism is suggested based on several techniques.The walnut HCs exhibited an attractive energy density of 279 Wh/kg when tested in full cells.
基金This work was supported by the Russian Science Foundation(Grant No.22-22-01031).
文摘The carrier-envelope phase(CEP)φ_(0)is one of the key parameters in the generation of isolated attosecond pulses.In particular,“cosine”pulses(φ_(0)=0)are best suited for generation of single attosecond pulses in atomic media.Such“cosine”pulses have the peak of the most intense cycle aligned with the peak of the pulse envelope,and therefore have the highest contrast between the peak intensity and the neighboring cycles.In this paper,the dynamics of single attosecond pulse generation from a relativistically oscillating plasma mirror is investigated.We use an elementary analytical model as well as particle-in-cell simulations to study few-cycle attosecond pulses.We find that the phase of the field driving the surface oscillations depends on the plasma density and preplasma scale length.This leads us to a counterintuitive conclusion:for the case of normal incidence and a sharp plasma-vacuum boundary,the CEP required for the generation of a single attosecond pulse phase is closer toφ_(0)=π/2(a“sine”pulse),with the exact value depending on the plasma parameters.
文摘This special issue consists of 12 invited reviews on the frontier areas of as- tronomy and astrophysics, and is aimed at a timely, in-depth evaluation of the current status and key progress, with suggestions for future directions. This special issue is particularly dedicated to the IAU XXVIIIth General Assembly （GA） and is complementary to the IAU GA Invited Discourses during the conference.
文摘Purpose: The present studied was performed in order to investigate the drug resistance of different non-lactose fermenting gram negative bacteria from clinical isolates. The bacteria were morphologically characterized through culturing and gram staining techniques were used for the identification of different bacterial strains. Methods: A total of 324 samples were collected from patients, after they were diagnosed by physicians at different hospitals at district Peshawar. Samples were morphologically identified by blood agar, MacConkey agar and Eosine Methylene Blue, identified by gram staining techniques. Modified Kirby-Bauer Disc diffusion method was used to test the in-vitro susceptibility of the identified isolates to different antibiotics. Results: The non-lactose fermenting gram negative bacteria were isolated from samples of blood (33.30%), pus/ wound (33.30%), urine (23.30%) and from ascetic/pleural fluids (10.20%). The study revealed that Pseudomonas aeroginosa showed high resistance against Gentamicin (74%) and Aztreonam (74%), followed by Ciprofloxacin (59.20%) and Amikacin (33.30). Tazocin was active as low resistance (18.50%) is shown. More resistance was seen in Morganella morganii against Aztreonam (77.7%) followed by Gentamicin (62.90%), Ciprofloxacin (40.70%). Tazocin show low resistance (3.70%). Multidrug resistant Proteus mirabillis was highly resistance to Gentamicin (66.60%), followed by Aztreonam (62.90%), Amikacin (55.50%), Ciprofloxacin (40.20%) and low resistance to Tazocin was (22.20%). Salmonella typhi demonstrated high resistance against Amikacin (62.90%), followed by Aztreonam (48.10%), Tazocin (40.70%). Gentamicin showed low resistance (29.60%), and hence it is more active against S. typhi. Conclusions: It can be concluded from the present study that different species of non-lactose fermenting gram negative bacteria have shown a different resistivity pattern. This study is a gate way for better and suitable management strategy for the infections caused by non-Lactose fermenting bacteria in the sampling region.
文摘Enhanced mobile broadband(e MBB) is one of the key use-cases for the development of the new standard 5G New Radio for thenext generation of mobile wireless networks. Large-scale antenna arrays, a.k.a. massive multiple-input multiple-output(MIMO), theusage of carrier frequencies in the range 10-100 GHz, the so-called millimeter wave(mm-Wave) band, and the network densifica-tion with the introduction of small-sized cells are the three technologies that will permit implementing e MBB services and realiz-ing the Gbit/s mobile wireless experience. This paper is focused on the massive MIMO technology. Initially conceived for conven-tional cellular frequencies in the sub-6 GHz range(μ-Wave), the massive MIMO concept has been then progressively extended tothe case in which mm-Wave frequencies are used. However, due to different propagation mechanisms in urban scenarios, the re-sulting MIMO channel models at μ-Wave and mm-Wave are radically different. Six key basic differences are pinpointed in thispaper, along with the implications that they have on the architecture and algorithms of the communication transceivers and on theattainable performance in terms of reliability and multiplexing capabilities.
文摘In order to contribute to the valorisation of the clay materials of Ivory Coast in the depollution of wastewater, the physicochemical and mineralogical characterization of three clay samples taken in Agboville (AGB), Bingerville (BIN) and Katiola (KAT) was carried out. The objective of this work was to compare the properties of the clays in order to identify the one that is likely to have interesting adsorptive capacities to clean up contaminated water. These clays were studied by chemical analysis, X-ray diffraction, scanning electron microscopy and thermal analysis. In addition, their specific surface areas and cation exchange capacities were determined. The AGB clay is composed of 75.51% kaolinite, 14.20% illite and 9.26% quartz. The BIN clay contains 52.21% kaolinite, 6.23% illite, 17.50% quartz and 15.71% goethite. As for the KAT clay, it contains 48.08% kaolinite, 3.55% illite, 20.14% smectite, 6.11% quartz and 16.86% goethite. Their thermal behavior and microstructure are in agreement with their mineralogy. The measured specific surface areas and cation exchange capacities are consistent with literature values. The KAT clay has the highest specific surface and cation exchange capacity. In the light of the results obtained, the KAT clay appears to be more effective in depolluting water than the BIN and AGB clays.
