Thermal Behavior of Composite Material Based on Phase Change Material/Plaster as Thermal Energy Storage in Multilayer Wall: Experimental Study.

This study aims to explore the effects of augmenting the mass proportion of a composite comprising paraffin and beeswax (PBPCM) within plaster, which influences the thermal insulation of a dual wall. This work is primarily based on the thermal properties of the composite material PBPCM/plaster with varying percentages of PBPCM. Various essential parameters, such as density, thermal conductivity, specific heat capacity, thermal diffusivity, and latent heat, were assessed and juxtaposed with those of conventional plaster for the PBPCM/plaster composite material. The evaluation of this composite material was executed through an experimental device on a laboratory scale. The obtained results show that the increase in the mass fraction of PBPCM in the plaster decreased the thermal conductivity of plaster more than 3 times, whereas this increase of the PBPCM fraction in plaster enhances heat retention, specifically in specific heat capacity under constant conditions. Nevertheless, in a dynamic state, thermal effusivity has the lowest value for 50% PBPCM. The recommendation is to utilize 50% PBPCM, as it yields an optimal thermal effusivity, and significant values of specific heat capacity and latent heat have been noted for this percentage of PBPCM, measuring 1263.77 kJ/kg K and 18.9 kJ, respectively. Additionally, an increase in the PBPCM percentage narrows the temperature range suitable for effective thermal energy storage.

Activated Carbon as an Adsorbent for CO2 Capture: Adsorption, Kinetics, and RSM Modeling.

The main objective of this research is to investigate the adsorption isotherms and the optimization of the carbon dioxide (CO2) adsorption process on activated carbon (AC). The AC has been characterized by X-ray diffraction, scanning electron microscopy, and nitrogen (N2) adsorption-desorption. The CO2 isotherms measured under three adsorption temperatures (318, 308, and 298 K) were investigated by the Langmuir and linear driving force model. It is found that the Langmuir model could well predict the adsorption behavior of AC with a correlation factor of about 0.99. The kinetic model shows that the amount of CO2 increases at higher pressures. The response surface methodology (RSM) was applied to investigate the effects of process variables and their interaction on the response to reach the optimal conditions. Based on the analysis of variance, pressure and temperature are the main factors influencing the CO2 adsorption capacity. The effective parameters obtained through this model are found to have a value of p < 0.05. In addition, a semiempirical correlation was developed under the optimal operating conditions which are 25 °C and 9 bar. The results indicated that RSM models provide an effective method for evaluating CO2 adsorption. These results point that AC is a potential adsorbent for CO2 capture.

Experimental and Theoretical Studies of Hydrogen Storage in LaNi4.4Al0.3Fe0.3 Hydride Bed.

In this article, the experimental measurements of the absorption/desorption P-C-T isotherms of hydrogen in the LaNi4.4Fe0.3Al0.3 alloy at different temperatures and constant hydrogen pressure have been studied using a numerical model. The mathematics equations of this model contain parameters, such as the two terms, nα and nß, representing the numbers of hydrogen atoms per site; Nmα and Nmß are the receptor sites' densities, and the energetic parameters are Pα and Pß. All these parameters are derived by numerically adjusting the experimental data. The profiles of these parameters during the absorption/desorption process are studied as a function of temperature. Thereafter, we examined the evolution of the internal energy versus temperature, which typically ranges between 138 and 181 kJmol-1 for the absorption process and between 140 and 179 kJmol-1 for the desorption process. The evolution of thermodynamic functions with pressure, for example, entropy, Gibbs free energy (G), and internal energy, are determined from the experimental data of the hydrogen absorption and desorption isotherms of the LaNi4.4Al0.3Fe0.3 alloy.

Experimental study of the microstructures and hydrogen storage properties of the LaNi4Mn0·5Co0.5 alloys.

In the present study, the absorption and desorption kinetics of hydrogen and the isotherm (P-C-T)) of the LaNi4Mn0·5Co0.5 alloy were measured at values of 283 K, 303 K, and 313 K. The morphological states of this sample were examined using characterization techniques, including X-ray diffraction and scanning electron microscopy. The thermodynamic functions for the absorption-desorption of hydrogen by hydrides, such as enthalpy (H) and entropy (S), were calculated from the experimental data or by using a model that exists in the literature and is premised on the adjustment of isotherm curves at various temperatures. This model is based on an integrated form of the Van't Hoff equation and a simultaneous examination of the isotherms. According to the experimental results, the amount of hydrogen absorbed or desorbed by the sample is significantly affected by the partial substitution of the nickel atom by the elements Mn and Co. However, this substitution increased the absorption or de-sorption plateau pressure.

Conception and Theoretical Study of a New Copolymer Based on MEH-PPV and P3HT: Enhancement of the Optoelectronic Properties for Organic Photovoltaic Cells.

A new copolymer has been studied, which is formed by Poly(2-methoxy-5-(2-ethyl-hexyloxy)-1,4-phenylene-vinylene) (MEH-PPV) and poly(3-hexylthiophene) (P3HT). The choice of these π-conjugated polymers was based on their semiconductor characters and their great applicability in electronic organic devices. The structure and vibrational and optoelectronic properties were simulated by calculations based on DFT, TD-DFT, and ZINDO. This material shows original and unique properties compared to the basic homopolymers. Thus, the obtained results reveal that this copolymer can be mixed with the (6,6)-phenyl C61 butyric acid methyl ester (PCBM) to give existence to a new composite that can be used as an active layer for an organic solar cell.

Photophysical Properties of the PVK-MEH-PPV/PCBM Composite for Organic Solar Cells Application: Synthesis, Characterization and Computational Study.

The physical and chemical properties of a new organic composite including PVK-MEH-PPV bi-block copolymer and [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) were recorded. The functionalization and the charge transfer that occurs between donor and acceptor were examined and computed. In fact, the stationary and time-resolved photoluminescence properties were used to examine the effect of the PCBM on the optical properties of the PVK-MEH-PPV matrix. The photoluminescence quenching accompanied by faster PL decay confirmed the charge transfer and interaction process. The electrical and optoelectronic properties and the charge carriers' injection in the resulting composite were examined. The experimental conclusion was corroborated and confirmed by a calculation based on density functional theory (DFT). Hence, the combination of experimental and theoretical results indicated that the result composite can be applied as an active layer for organic solar cells.

Complementary Study Based on DFT of Optical and Electronic Properties of New Copolymer PVK-F8T2.

This article is mainly a complementary study of a novel part of π-conjugated copolymers based on the poly (N-vinylcarbazole) (PVK) and poly (9,9-dioctylfluorene-co-bithiophene) (F8T2) unit based on the Density Functional Theory (DFT) and Time-Dependent Density Functional Theory (TD-DFT). This study is carried out to explore the structural and optoelectronic characteristics of a new organic material named PVK-F8T2. First, the structural, optical (absorption, photoluminescence, optical transition), electronic (molecular orbital (MO), energy-level diagram) and vibratory parameters of infrared (IR) were computed and compared with experimental studies. In addition, we calculated the level energy of the excited states and their corresponding transitions. Obviously, electronic parameters such as highest occupied and lowest unoccupied molecular orbital (HOMO and LUMO), ionization potential (IP), electronic affinity (EA) and the energy band gap (Eg) were computed in order to elucidate the intramolecular charge transport and to establish the energetic diagrams of the PVK-F8T2 copolymer for different states. The results obtained looked with precision at future optoelectronic applications. From these results, we have shown that the PVK-F8T2 has significant optoelectronic properties and seems usable as an active layer in organic light-emitting diodes (OLEDs).

Epidemiological characteristics, management, and outcomes of atrial fibrillation in TUNISIA: Results from the National Tunisian Registry of Atrial Fibrillation (NATURE-AF).

BACKGROUND: Contemporary registries on atrial fibrillation (AF) are scare in North African countries. HYPOTHESIS: In the context of the epidemiological transition, prevalence of valvular AF in Tunisia has decreased and the quality of management is still suboptimal. METHODS: NATURE-AF is a prospective Tunisian registry, involving consecutive patients with AF from March 1, 2017 to May 31, 2017, with a one-year follow-up period. All the patients with an Electrocardiogram-documented AF, confirmed in the year prior to enrolment were eligible. The epidemiological characteristics and outcomes were described. RESULTS: A total of 915 patients were included in this study, with a mean age of 64.3 ± 22 years and a male/female sex ratio of 0.93. Valvular AF was identified in 22.4% of the patients. The mean CHA2 DS2 VASC score in nonvalvular AF was 2.4 ± 1.6. Monotherapy with antiplatelet agents was prescribed for 13.8% of the patients. However, 21.7% of the subjects did not receive any antithrombotic agent. Oral anticoagulants were prescribed for half of the patients with a low embolic risk score. In 341 patients, the mean time in therapeutic range was 48.87 ± 28.69%. Amiodarone was the most common antiarrhythmic agent used (52.6%). During a 12-month follow-up period, 15 patients (1.64%) had thromboembolism, 53 patients (5.8%) had major hemorrhage, and 52 patients (5.7%) died. CONCLUSIONS: NATURE-AF has provided systematic collection of contemporary data regarding the epidemiological and clinical characteristics as well as the management of AF by cardiologists in Tunisia. Valvular AF is still prevalent and the quality of anticoagulation was suboptimal.

Self-ordering promoted by the nanoconfinement of poly(3-hexylthiophene) and its nanocomposite with single-walled carbon nanotubes.

Nanostructuration and self-ordering of semiconducting organic materials are required to fabricate highly efficient photovoltaic and photoemissive devices. In this work, we investigated the combined effect of melt-assisted template processing and self-ordering of high purity regio-regular poly (3-hexylthiophene) (P3HT) to obtain nanofibers of P3HT and of P3HT-single-walled carbon nanotubes (SWNT) nanocomposites. An original ordering of the polymer and the carbon nanotubes within the nanofibers, as well as their surprising anisotropic photoluminescent properties were determined by vibrational and optical spectroscopy. It was attributed to the combined effect of the melt-assisted wetting confined within alumina nanopores, altogether with the self-organization of both P3HT chains on the one hand, and of the P3HT charged with SWNT on the other hand. It is proposed that the well-ordered regio-regular P3HT matrix orientation is promoted by the interaction with the alumina pore surface and the 1D confinement. For the composite case, the P3HT matrix imposes additionally a preferential orientation of the SWNT transversal to the nanofiber axis. This original organization is responsible for the unexpected polarization of the composite nanofibers photoluminescence. This work opens the way to alternative methods for tackling challenges of nanofabrication to obtain more efficient optoelectronic nanodevices.

Design and Rationale of the National Tunisian Registry of Atrial Fibrillation: Protocol for a Prospective, Multicenter Trial.

BACKGROUND: Atrial fibrillation (AF) is an important health problem in Tunisia. A significant change in the epidemiological pattern of heart disease has been seen in the last 3 decades; however, no large prospective multicenter trial reflecting national data has been published so far. Robust data on the contemporary epidemiological profile and management of AF patients in Tunisia are limited. OBJECTIVE: The aim of this study is to analyze, follow, and evaluate patients with AF in a large multicenter nationwide trial. METHODS: A total of 1800 consecutive patients with AF by electrocardiogram, reflecting all populations of all geographical regions of Tunisia, will be included in the study, with the objective of describing the epidemiological pattern of AF. Patients will be officially enrolled in the National Tunisian Registry of Atrial Fibrillation (NATURE-AF) only if an electrocardiogram diagnosis (12-lead, 24-hour Holter, or other electrocardiographic documentation) confirming AF is made. The qualifying episode of AF should have occurred within the last year, and patients do not need to be in AF at the time of enrollment. Patients will be followed for 1 year. Incidence of stroke or transient ischemic attack, thromboembolic events, and cardiovascular death will be recorded as the primary end point, and hemorrhagic accidents, measurement of international normalized ratio, and time in therapeutic range will be recorded as secondary end points. RESULTS: Results will be available at the end of the study; the demographic profile and general risk profile of Tunisian AF patients, frequency of anticoagulation, frequency of effective treatment, and risks of thromboembolism and bleeding will be evaluated according to the current guidelines. Major adverse events will be determined. NATURE-AF will be the largest registry for North African AF patients. CONCLUSIONS: This study would add data and provide a valuable opportunity for real-world clinical epidemiology in North African AF patients with insights into the uptake of contemporary AF management in this developing region. TRIAL REGISTRATION: ClinicalTrials.gov NCT03085576; https://clinicaltrials.gov/ct2/show/NCT03085576 (Archived by WebCite at http://www.webcitation.org/6zN2DN2QX). REGISTERED REPORT IDENTIFIER: RR1-10.2196/8523.

[Use of catecholamines for shock. A continuous debate!]. / L'utilisation des Catecholamines dans les etats de choc. Le debat continue!

BACKGROUND: Hypotension and shocks are frequently observed in patients requiring admission in ICU. However, the optimal adrenergic support in shock is controversial. AIM: To perform a descriptive approach of the current use of catecholamine in a medico-surgical ICU in patients with schoks. METHODS: Our study is prospective over 3 month period. Were included all patients admitted in our ICU during the study period's. We compared the populations with and without catecholamine, we analysed the catecholamine selected in various clinical settings and we studied the impact of the use of catecholamine on the patient outcomes. RESULTS: During the study's period, 226 patients were hospitalized in our service and were the subject of this study. The median age (± SD) was of 47± 24 years. During their hospitalization in the ICU, 132 patients (58.4%) presented a shock. The cardiogenic shock and the hypovolemic shock were the most observed (37.8% and 35.6% respectively). Hundred thirty patients (57.5%) received catecholamines during their stay in ICU. Eighty four patients (64.6% of the patients having received catecholamines) had received dopamine. Sixty two patients (47.7% of the patients having received catecholamines) had received dobutamine, 63 patients (48.5%) had received epinephrine and 22 patients (16.9%) had received norepinephrine. The mean's period of catecholamines use was 5 ± 4 days. Among drugs proposed in order to manage patients with cardiogenic shock, dobutamine was chosen as the first choice agent in 62% of the cases. Among drugs proposed in order to manage patients with septic shock, Dopamine was chosen as the first choice agent in 85.7 % of the cases. In our study the patients of the class C or D in the Knauss classification are significantly predisposed to receive catecholamines during their ICU stay (OR: 5.3 ; IC 95% : 1.7 - 5.7).Moreover, the needing of catecholamine use is strongly associated with high mortality (OR: 16,8; IC 95% : 16.4 - 49.2). CONCLUSION: The choice of catecholamines is a matter of debate for critically ill patients. The use of catecholamines is a clinical marker of severity and provider of mortality.

Use of heptaminol hydrochloride for catecholamine weaning in septic shock.

We analyze in the current study the impact of heptaminol hydrochloride (Heptamyl) administration in patients with septic shock requiring adrenergic support on the duration of vasopressor infusion and on catecholamine delay weaning. In this prospective study were included 49 nonconsecutive patients with septic shock requiring vasopressor infusion and with stable hemodynamic parameters during more than 24 hours. All these patients were included in a random way to receive or not heptaminol hydrochloride. The primary end point was the effect of heptaminol hydrochloride administration on duration of weaning, defined as cessation of vasopressor support. There were 32 males (65%) and 17 females (35%). The mean age (± standard deviation) was 53.9 ± 22.2 years. Norepinephrine was the most commonly used vasopressor agent (73.4%). The comparison between two groups (with and without heptaminol hydrochloride) showed that two groups had the same epidemiologic, clinical, and biologic findings on intensive care unit admission. In our study, we found that the introduction of Heptamyl was associated with a quick decrease of dose of dopamine and norepinephrine in comparison with the Heptamyl-free group. By comparing the two groups, we found that the delay of catecholamine weaning was significantly faster for the dopamine (P = 0.008) and noradrenalin (P = 0.001) in the Heptamyl group. Finally, the intensive care unit mortality rate and the hospital mortality rate were significantly lower in the Heptamyl group. Our study shows a reduction in norepinephrine and dopamine weaning duration in septic patients enrolled in the heptaminol hydrochloride group.

[Coronary arteriography in severe aortic valve disease]. / La coronarographie dans les valvulopathies aortiques sévères.

Three hundred and twelve patients with severe aortic valve disease underwent a pre-operative haemodynamic study including coronary arteriography either as routine (age more than 50 years) or because of chest pains, previous myocardial infarction or for patients with risk factors of coronary atherosclerosis. Significant coronary artery disease was present in 9% of all cases. Coronary artery disease was more frequent in patients with angina and in patients with previous myocardial infarction but none of these factors was specific. We conclude that except young patients < 40 years old, with no chest pain and no coronary risk factors, coronary arteriography is recommended in patients with severe aortic valve disease before aortic valve replacement.

[Twenty years result of a corrective surgery of tetralogy of Fallot in a 50 years old woman]. / Resultat a 20 ans d'une reparation complete d'une tetralogie de Fallot chez une femme de 50 ans.

The authors report the case of a woman operated at a 50 years of age for a tetralogy of Fallot with a good late result.

[Multiple coronary artery-left ventricular fistulae. A case report]. / Fistules coronaires multiples dans la cavite ventriculaire gauche. A propos d'un cas.

The authors report the case of a patient with multiple coronary artery-left ventricular fistulae discovered in coronary angiography for exertional angina.

[Percutaneous mitral commissurotomy and left ventricular function in severe mitral stenosis]. / Commissurotomie mitrale percutanée et fonction ventriculaire gauche dans le retrecissement mitral serré.

The purpose of this study was to determine the immediate effect of percutaneous mitral commissurotomy (PMC) on left ventricular (LV) performance. We studied 30 patients with severe mitral stenosis undergoing successful PMC by cardiac catheterization and angiography before and 5 minutes after PMC. All patients were in sinus rhythm and no patient had hypertension or clinical coronary artery disease. We conclude that the left ventricular end-diastolic volume and the stroke volume increased significantly immediately after PMC because of and increase in LV filling after relieving the mitral mechanical obstruction.

[Pulmonary hypertension in sickle cell anemia. A case report]. / L'hypertension artérielle pulmonaire dans la drépanocytose. A propos d'une observation.

We report the case of a 33-years-girl with SCA and severe PH. She developed six month before admission, non productive cough and dyspnea. Physical examination at admission revealed shortness of breath and right heart ventricular failure. Electrocardiography showed sinus rhythm and an incomplete left bundle branch block. Chest roentgenography revealed cardiomegaly with cardiothoracic index at 0.66 and pulmonary infiltrates. Laboratory tests revealed an anemia with hemoglobin of 7.1 g/dl, white blood cell count of 12,500/mm, moderate renal failure (cretininemia = 178 mumol/l) and hypoxemia with oxygen pressure of 60 mmHg. Hemoglobin electrophoresis revealed on heterozygous SCA. Echocardiography revealed dilatation of right heart cavities and a systolic pulmonary artery pressure of 60 mmHg. A perfusion lung scintigraphy demonstrated multiple subsegmental perfusion defects. PH is a common complication of adult patients with SCA. Appropriate therapies and strategies for prevention of PH in SCA are unknown. Further research exploring therapies such as oxygen, nitric oxide, prostacyclin and hydroxyurea are indicated.