328 research outputs found
Sorption Study of a Basic Dye âGentian Violetâ from Aqueous Solutions Using Activated Bentonite
AbstractVarious industries like textiles, papers, food, plastics, leather, etc are great water and organic colorant users. Hence, the resulting effluents could be an important source of environmental problems, since they may contain stable and non biodegradable contaminants, like organic dyes. The treatment of which is the main scope of the present study. Different ways of dye removal from these effluents do exist, such as flotation, reverse osmosis, chemical flocculation and adsorption etc. Adsorption is used in this work for the removal of a particular basic dye, known as Gentian violet (GV) from an aqueous solution, by means of a natural clay material. The influence of various key parameters like contact time, temperature, ionic strength, etc. on the adsorbed amount of the dye was investigated, for batch conditions. A kinetic study was also carried out, the obtained experimental results were tested against the pseudo first order and the pseudo second order equations. An analysis of the obtained equilibrium data showed that the dye adsorption is best described by the Langmuir model. The obtained results showed that temperature did enhance the Gentian violet dye retention process onto the considered bentonite whereas the obtained thermodynamic parameters indicated that the adsorption process is spontaneous and endothermic. The simultaneous presence of methylene blue, which is another colorant compound, with the Gentian violet was also considered. The clay materials showed a better affinity for the first one i e. methylene blue. In conclusion and according to the obtained results, the clay material may be recommended as an industrial adsorbent for the treatment of effluents containing Gentian violet (GV)
Risk factors caused by scorpion stings and envenomations in the province of KelĂąa Des Sraghna (Morocco)
The present study aims to elucidate the risk factors involved in deaths caused by scorpion envenomation. A retrospective study was carried out in the province of KelĂąa des Sraghna from 2003 to 2004. The hospital charts of scorpion envenomation cases treated in the Essalama Hospital in KelĂąa des Sraghna were exhaustively analyzed. Our study contains 31 cases of death among 470 hospitalization cases. Most stings had occurred during the hot period peaking in July and August (54.6%). Moreover, the scorpion stings occurred at night in 60.1% of the cases, between 6:00 pm and 6:00 am. In addition, all age groups were affected by envenomation, with a higher frequency in children aged less than 15 years (68.3%). The envenomation rate (class II + class III) was 70.9%. The statistical analysis of the data shows that being less than 15 years old, having been stung during the night and belonging to class III are risk factors that aggravate vital prognosis of hospitalized patients. Furthermore, clinical severity factors, elicited by relative risk analysis, are cardiovascular, respiratory and neurological vital distresses, with relative risks of 14.84, 11.92 and 48.33, respectively. The results of our study clearly displayed the severity and extent of the scorpion envenomation problem. Thus, great attention must be paid to this region of Morocco by the national health authorities
Thermal Performance of Hybrid PVT Collector with Natural Circulation
Hybrid photovoltaic thermal (PVT) collectors allow simultaneous production of electrical energy thus heat energy. There are several configurations of hybrid collectors (to produce water or air). For hybrids water collectors, there are several configurations that differ by the nature of the absorber (serpentine, tubes...). In this paper, an absorber tank is studied. The circulation of the coolant is natural (we do not use the pump). We present the obtained results in our experimental study and we analyzed the data, and then we compare the results with the theory practices. The electrical performances of the hybrid collector are compared with those of conventional photovoltaic module mounted on the same structure and measured under the same conditions. We conducted experiments with natural circulation of the coolant (Thermosyphon), for a flow rate of 0.025kg/mÂČ
On the equivalence of pairing correlations and intrinsic vortical currents in rotating nuclei
The present paper establishes a link between pairing correlations in rotating
nuclei and collective vortical modes in the intrinsic frame. We show that the
latter can be embodied by a simple S-type coupling a la Chandrasekhar between
rotational and intrinsic vortical collective modes. This results from a
comparison between the solutions of microscopic calculations within the HFB and
the HF Routhian formalisms. The HF Routhian solutions are constrained to have
the same Kelvin circulation expectation value as the HFB ones. It is shown in
several mass regions, pairing regimes, and for various spin values that this
procedure yields moments of inertia, angular velocities, and current
distributions which are very similar within both formalisms. We finally present
perspectives for further studies.Comment: 8 pages, 4 figures, submitted to Phys. Rev.
Correlated twin-photon generation in a silicon nitride loaded thin film PPLN waveguide
Photon-pair sources based on thin film lithium niobate on insulator technology have a great potential for integrated optical quantum information processing. We report on such a source of correlated twin-photon pairs generated by spontaneous parametric down conversion in a silicon nitride (SiN) rib loaded thin film periodically poled lithium niobate (LN) waveguide. The generated correlated photon pairs have a wavelength centred at 1560 nm compatible with present telecom infrastructure, a large bandwidth (21 THz) and a brightness of âŒ2.5 Ă 105 pairs/s/mW/GHz. Using the Hanbury Brown and Twiss effect, we have also shown heralded single photon emission, achieving an autocorrelation g (2) H (0) â 0.04.Antoine Henry, David Barral, Isabelle Zaquine, Andreas Boes, Arnan Mitchell, Nadia Belabas, and Kamel Bencheik
Quantum key distribution using gaussian-modulated coherent states
Quantum continuous variables are being explored as an alternative means to
implement quantum key distribution, which is usually based on single photon
counting. The former approach is potentially advantageous because it should
enable higher key distribution rates. Here we propose and experimentally
demonstrate a quantum key distribution protocol based on the transmission of
gaussian-modulated coherent states (consisting of laser pulses containing a few
hundred photons) and shot-noise-limited homodyne detection; squeezed or
entangled beams are not required. Complete secret key extraction is achieved
using a reverse reconciliation technique followed by privacy amplification. The
reverse reconciliation technique is in principle secure for any value of the
line transmission, against gaussian individual attacks based on entanglement
and quantum memories. Our table-top experiment yields a net key transmission
rate of about 1.7 megabits per second for a loss-free line, and 75 kilobits per
second for a line with losses of 3.1 dB. We anticipate that the scheme should
remain effective for lines with higher losses, particularly because the present
limitations are essentially technical, so that significant margin for
improvement is available on both the hardware and software.Comment: 8 pages, 4 figure
Risk factors for MERS coronavirus infection in dromedary camels in Burkina Faso, Ethiopia, and Morocco, 2015
Understanding Middle East respiratory syndrome coronavirus (MERS-CoV) transmission in dromedary camels is important, as they consitute a source of zoonotic infection to humans. To identify risk factors for MERS-CoV infection in camels bred in diverse conditions in Burkina Faso, Ethiopia and Morocco, blood samples and nasal swabs were sampled in February-March 2015. A relatively high MERS-CoV RNA rate was detected in Ethiopia (up to 15.7%; 95% confidence interval (CI): 8.2-28.0), followed by Burkina Faso (up to 12.2%; 95% CI: 7-20.4) and Morocco (up to 7.6%; 95% CI: 1.9-26.1). The RNA detection rate was higher in camels bred for milk or meat than in camels for transport (p = 0.01) as well as in younger camels (p = 0.06). High seropositivity rates (up to 100%; 95% CI: 100-100 and 99.4%; 95% CI: 95.4-99.9) were found in Morocco and Ethiopia, followed by Burkina Faso (up to 84.6%; 95% CI: 77.2-89.9). Seropositivity rates were higher in large/medium herds (â„51 camels) than small herds (p = 0.061), in camels raised for meat or milk than for transport (p = 0.01), and in nomadic or sedentary herds than in herds with a mix of these lifestyles (p < 0.005).published_or_final_versio
Scorpion sting: a public health problem in El Kelaa des Sraghna (Morocco)
The present study aimed at verifying the impact of a Moroccan strategy against scorpion stings and specifically at identifying the epidemiological features of patients envenomed or just stung by scorpions. It included 11,907 patients from El Kelaa des Sraghna Province, Morocco, who were evaluated over five years (2001-2005). Most stings occurred during the hot period and mainly at night. The average incidence was 3.2 per 1,000 inhabitants; patients <15 years accounted for 34%, and the envenomation rate was 12%. Average lethality rate was 0.7%. Our work evaluated the efficacy of the adopted strategy based on indicators of follow-up, morbidity and lethality due to scorpion sting and envenomation
Time-odd components in the mean field of rotating superdeformed nuclei
Rotation-induced time-odd components in the nuclear mean field are analyzed
using the Hartree-Fock cranking approach with effective interactions SIII,
SkM*, and SkP. Identical dynamical moments are obtained for
pairs of superdeformed bands Tb(2)--Dy(1) and
Gd(2)--Tb(1). The corresponding relative alignments strongly
depend on which time-odd mean-field terms are taken into account in the
Hartree-Fock equations.Comment: 23 pages, ReVTeX, 6 uuencoded postscript figures include
PT-symmetric Solutions of Schrodinger Equation with position-dependent mass via Point Canonical Transformation
PT-symmetric solutions of Schrodinger equation are obtained for the Scarf and
generalized harmonic oscillator potentials with the position-dependent mass. A
general point canonical transformation is applied by using a free parameter.
Three different forms of mass distributions are used. A set of the energy
eigenvalues of the bound states and corresponding wave functions for target
potentials are obtained as a function of the free parameter.Comment: 13 page
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