Crystal structure, optical characterization, conduction and relaxation mechanisms of a new hybrid compound (C6H9N2)2[Sb2Cl8].

Hybrid materials play a crucial role in the construction of flexible electronic devices due to the advantages of both organic and inorganic components. To this end, a new hybrid compound (C6H9N2)2[Sb2Cl8] was successfully fabricated using the slow evaporation solution growth approach at room temperature. In-depth research has been done on the structural, optical, and dielectric characteristics. This compound adopts the triclinic symmetry and crystallizes in the centrosymmetric space group P1̄. The inorganic and organic components respectively form anionic and cationic layers parallel to the ac-plane and alternate along the crystallographic b-axis. The [Sb2Cl8]2- dimeric units are bound to the 2-amino-5-picolinium cations [(C6H9N2)]+ through N-H⋯Cl hydrogen bonds. Optical absorption measurements showed a semiconductor behavior with a band gap of approximately 3.57 eV. In addition, DFT calculations were performed to investigate the absorption spectrum, wavelength, and HOMO-LUMO gap. The analysis of complex impedance spectra shows that the electrical conductivity of the sample is strongly frequency and temperature dependent, indicating a relaxation phenomenon and semiconductor-type behavior. Dielectric data obtained from complex impedance spectroscopy and ac conductivity with the use of the Maxwell-Wagner equivalent circuit model, and the universal power law have been investigated to explore the basic components of the electronic transport and relaxation process in our material.

Crystal structure and optical characterization of a new hybrid compound, C6H9N2FeCl4, with large dielectric constants for field-effect transistors.

Due to remarkable dielectric features, such as a large dielectric constant, strong electrical conductivity, high capacitance, and low dielectric loss, hybrid materials have lately seen a huge number of applications in the field of optoelectronics. These are critical characteristics that qualify the performance of optoelectronic devices, particularly field-effect transistor components (FETs). Here, the hybrid compound 2-amino-5-picoline tetrachloroferrate(iii) (2A5PFeCl4) was synthesised by using the slow evaporation solution growth method at room temperature. Structural, optical, and dielectric properties have been investigated. The 2A5PFeCl4 compound crystallises in the monoclinic system (P21/c space group). Its structure can be described as a successive layering of inorganic and organic parts. [FeCl4]- tetrahedral anions and 2-amino-5-picolinium cations are connected by N-H⋯Cl and C-H⋯Cl hydrogen bonds. The optical absorption measurement confirms the semiconductor nature with a band gap of around 2.47 eV. Additionally, the structural and electronic properties of the title compound have been investigated theoretically through DFT calculations. At low frequencies, this material has significant dielectric constants (ε ∼106). Furthermore, the high electrical conductivity, low dielectric loss at high frequencies, and high capacitance show that this new material has great dielectric potential in FET technologies. Due to their high permittivity, these compounds can be employed as gate dielectrics.

AC conductivity and phase transition of the BST-BFO ceramic doped with Yb.

The homogeneity of the 0.8(Ba0.8Sr0.2)TiO3-0.2(Bi0.85Yb0.15)FeO3 ceramic, prepared by a solid-state process, was studied and quantitatively analyzed by scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX). At ambient temperature, X-ray diffraction shows the existence of only one perovskite phase in the tetragonal structure with the space group P4mm. The thermal variations of (real part of the dielectric permittivity) for this composition show extended peaks with temperature; this broadening of the peaks can be attributed to the diffuse character of the transition. As the frequency increases, T m (temperature of maximum permittivity) moves at higher temperatures, and the maximum values of decrease. Moreover, the impedance spectra (-Z'' vs. Z') show the presence of two arcs of circles that have been modeled with an equivalent electrical circuit. The arcs of the circles centered under the real axis (Z) prove the Cole-Cole-type behavior. Each circle is associated with either the grain effect or grain boundaries. Electrical modulus analysis shows that the capacitance of the ceramic is enhanced, which is in good agreement with the results of complex impedance analysis. The AC conductivity complies with the universal power law. It disputes the modification of AC conductivity by adopting the Arrhenius-type of electrical conductivity. The temperature dependence of alternating current conductivity (σ g) and direct current conductivity (σ DC) confirms the existence of the ferroelectric-paraelectric phase transition.

Investigation of optical and electrical properties of the semiconducting α-KZnPO4 compound.

We used the solid state method to synthesize the α-KZnPO4 compound. The X-ray diffraction pattern revealed that the sample represents a single hexagonal phase with a P63 space group. The chemical composition of the compound was examined by energy dispersive spectroscopy. The optical absorption measurement confirmed the semiconductor nature of the compound with a band gap around 4.52 eV. Furthermore, the electrical properties of the material were analyzed by means of the impedance spectroscopy, in a frequency range from 100 Hz to 1 MHz and a temperature range from 583 K to 673 K. The dependency of s(T) on temperature showed that the overlapping large polaron tunneling model is the mechanism responsible for AC conduction in the compound. A correlation between the crystal structure and the ionic conductivity was established and discussed. Finally, the temperature variation of M'' peak showed a thermally activated relaxation process and a temperature-dependent stretching exponent ß parameter.

Synthesis, structural and electrical characterization of a new organic inorganic bromide: [(C3H7)4N]2CoBr4.

A new organic inorganic hybrid [TPA]2CoBr4, where TPA = [(C3H7)4N]+ (i.e., tetra-propyl-ammonium) compound has been synthesized by slow evaporation method at room temperature. Single crystal X-ray diffraction (SC-XRD), X-ray powder diffraction (XRPD), thermal analyses, vibrational and complex impedance spectroscopy have been used to characterize both structural, thermal, electrical properties. [TPA]2CoBr4 crystallizes in the monoclinic system (C2/c space group) with the following cell parameters: a = 33.145 (5) Å, b = 14.234 (3) Å, c = 15.081 (2) Å and ß = 110.207 (5)°. In the crystal structure, the organic TPA cations which form layers stacked along the a-axis, are separated from each other by inorganic tetrahedral [CoBr4]2- anions. The XRPD pattern confirms both the high purity of the sample and the crystalline nature of the powder. The differential scanning calorimetry (DSC) analysis shows an endothermic peak at 394 K upon heating which is ascribed to a structural phase transition since no decomposition of the titled compound is evidenced by thermogravimetric analysis. The ac conductivity and the dielectric properties confirm the presence of the phase transition. At the structural phase transition around 394 K, a change from a quantum mechanical tunneling to a correlated barrier hopping conduction models is determined from the temperature dependence of the exponent s of the Jonscher's power law. The analysis of complex impedance spectra shows that the electrical properties of the material are heavily dependent on frequency and temperature, indicating a relaxation phenomenon and semiconductor-type behavior. One single semicircle is detectable in the Nyquist plots of the complex impedance spectra which can be satisfactorily fitted with a combination R//CPE elements assigned to the bulk response. This behavior suggests that the sample is electrically homogeneous. Capacitance analysis proves the high effective permittivity at radio frequencies in the sample.

Studies on structural, dielectric and optical properties of (Ba0.95Ca0.05)1-x (Ti0.8Sn0.2)1-x Na x Nb x O3 lead-free ceramics.

(Ba0.95Ca0.05)1-x (Ti0.8Sn0.2)1-x Na x Nb x O3 (BCNTSNO3) lead-free ceramics with compositions (x = 0.75, 0.8 and 0.85) were synthesized through the traditional solid-state reaction method. X-ray powder diffraction analysis showed the formation of a single phase compound crystallized in tetragonal space group P4mm. The evolution of Raman spectra displayed a disorder introduced into the structure, which favors a ferroelectric relaxor behavior. The dependence of the dielectric properties on temperature exhibited two composition ranges with different behaviors. Ferroelectric relaxor properties were observed for the compositions x < 0.85 and the classical ferroelectric behavior for x = 0.85. Lead free (Ba0.95Ca0.05)1-x (Ti0.8Sn0.2)1-x Na x Nb x O3 ceramics exhibited larger dielectric constants than those of parent crystal NaNbO3, suggesting that it is a good candidate for lead-free ceramics in several industrial applications. Using UV-Vis spectroscopy, the optical band gap energy of ceramics (Ba0.95Ca0.05)1-x (Ti0.8Sn0.2)1-x Na x Nb x O3 is found at 2.89, 2.92, and 3.05 eV for x = 0.75, 0.8 and 0.85, respectively.

Splenogonadal fusion - a rare cause of scrotal swelling: a case report.

BACKGROUND: Splenogonadal fusion is a rare and benign condition. Diagnosis is challenging for clinicians. Despite its indolence, diagnosis is often confirmed after orchidectomy. Surgery is mandatory, particularly to rule out the extremely rare association with malignancy. CASE PRESENTATION: We report a case of splenogonadal fusion in a 38-year-old North African man presenting a palpable scrotal mass. We describe clinical aspects, pathogenic hypothesis, radiological features, as well as surgical management principles. CONCLUSIONS: Splenogonadal fusion is rarely suspected and diagnosed preoperatively. A diagnosis is made once an ectopic testicular mass is associated with cryptorchidism and suggestive radiological signs. A better knowledge of the clinical and radiological features of splenogonadal fusion provides an opportunity for conservative surgery.

Electrical conductivity and vibrational studies induced phase transitions in [(C2H5)4N]FeCl4.

The compound, tetraethylammonium tetrachloroferrate [(C2H5)4N]FeCl4, was prepared by slow evaporation at room temperature. It was characterized by X-ray powder diffraction, thermal analysis, and impedance and vibrational spectroscopy. X-ray diffraction data confirmed formation of a single phase material which crystallized at room temperature in the hexagonal system (P63 mc space group). DSC showed the existence of two phase transitions at 413 K and 430 K. Electrical conductivity was measured in the temperature and frequency ranges of 390 K to 440 K and 40 Hz to 110 MHz, respectively. Nyquist plots revealed the existence of grains and grain boundaries that were fitted to an equivalent circuit. AC conductivity plots were analyzed by Jonscher's power law. Variations in the "s" values indicated that CBH models describe the conduction mechanism in regions I and II. Temperature dependence of Raman spectra showed that the most important changes were observed in the cationic parts ([(C2H5)4N]+). The activation energy value obtained from the line width decreased which indicated an order-disorder model.

Assessment of genetic diversity of Tunisian orange, Citrus sinensis (L.) Osbeck using microsatellite (SSR) markers.

Citrus are one of the most cultivated crops in the world. Economically, they are very important fruit trees in Tunisia. Little is known about the genetic diversity of the Tunisian Citrus germplasm. Exploring this diversity is a prerequisite for the identification and characterization of the local germplasm to circumvent and controlling genetic erosion caused by biotic and abiotic stress to aid its conservation and use. In the present study, we explored the genetic diversity of 20 Tunisian orange cultivars [Citrus sinensis (L.) Osbeck] and established their relationships by using seven simple sequence repeat (SSR) loci. In total, 37 alleles and 44 genotypes were scored. The sizes of alleles ranged from 90 to 280 bp. The number of alleles per locus was from 4 to 7, with an average of 5.28. Polymorphic information content value changed from 0.599 to 0.769 with an average of 0.675. Analysis of the genotypes revealed a heterozygote deficiency across all the genotypes. The observed heterozygosity varied from 0 to 1 (average of 0.671). Cluster analysis showed that three groups could be distinguished and the polymorphism occurred independently of the geographical origin of the studied orange cultivars. The detected SSR genotypes allowed the establishment of an identification key with a discriminating power of 100%. Multivariate analysis and the neighbor-joining phylogenetic tree indicated a narrow genetic base for the orange cultivars. The usefulness of SSR markers for orange fingerprinting and evaluation of the genetic diversity in the Tunisian germplasm are discussed in this paper.

Using Raman spectroscopy to understand the origin of the phase transitions observed in [(C3H7)4N]2Zn2Cl6 compound.

Phase transitions of the centrosymmetric compound, [(C3H7)4N]2Zn2Cl6, were studied by differential scanning calorimetry (DSC), X-ray diffraction, Raman spectroscopy and dielectric measurements. Two reversible order-disorder and displacive phase transitions are observed at T1=327K and T2=347K with 3K and 4K hysteresis respectively, indicating a first order character. The evolution of Raman line shifts, "ν", and the half-width, "Δν", versus temperature show some singularities associated with the transitions, suggesting that they are governed by the reorientational and the displacement of the organic part. Besides the results of the dielectric permittivity study confirms the conclusion drawn from the calorimetric and Raman measurements that the phase transition located in the vicinity of the temperature of the dielectric proprieties is characterized by change of dynamical state of cation.

[Predictive factors of esophagojejunal fistula after total gastrectomy in gastric cancer patients]. / Facteurs prédictifs du lâchage de l'anastomose oeso-jéjunale après gastrectomie totale pour cancer.

BACKGROUND: The main complication observed after total gastrectomy is the oesophagojejunal anastomosic fistla. Its incidence varies between 7.4% and 11.5%. The mortality after anastomic leafage is high at around 20%, representing 30% and 54% of global mortality after total gastrectomy. AIM: This study aimed to evaluate mortality and morbidity after total gastrectomy and to determine their predictive factor METHODS: this is retrospective study about 80 cases of total gastrectomy for gastric cancer, collected in the departmentof General Surgery of the University Hospital Habib Thameur Tunis during the period 1 January 1995 to 31 December 2010. Reconstruction of the alimentary tract was achieved by Roux-en-Y-jejunal-loop. RESULTS: Esophagojejunal anastomotic leeakage developed in 14 patients (17%). In 8 patients treatment of anastomotic leakage consisted of re-operation with surgical drainage and confection of jejunostomy. in one patient treatment required resutre of the anastomosis and drainage of an abscess. In one patient treatment required resuture of the anastomosis and drainage of an abscess. in 5 of the 14 patients with a proven leak of oesophagojejunal anastomosis, conservative treatment with parental alimentation, placement of an irrigation-aspiration system and systemic antibiotics was performed. This treatment was successful in all cases. The presence of anastomic fistula extends the median lenght of post operative stay in the hospital of 20 days compared for the payents withiut fistula.Global mortalilty was 8/80 (10%). After esophagojejunal anastomotic leakage, the mortality was 3/8 (21%). CONCLUSION: Leakage of the oesophago-intestinal anastomosis may occur after total gastrectomy for gastric cancer. it's serious complication contributes to mortality after total gastrectomy. Knowledge of the predective factors of esophagojejunal fistula after total gastrectomy in gastric cancer can decrease its incidence .

[Celiac disease revealed by hypocalcemia complicating total thyroidectomy: a case report]. / Maladie coeliaque révélée par une hypocalcémie secondaire à une thyroïdectomie totale: à propos d'un cas.

In order to illustrate a particular circumstance of diagnosis of celiac disease, we report the case of 54-year-old women with a history of thyroid enlargement with normal thyroid function and positive anti-peroxidase antibodies. Immediately after total thyroidectomy with preservation of the parathyroid glands, she developed tetany with total serum calcium level at 50mg/l. Intravenous calcium infusion increased the calcium level and led to resolution of hypocalcemia-induced signs but there was no result when calcium and vitamin D were taken orally. The diagnosis of malabsorption was very probable in light of the family history of celiac disease, the anemia and the hypoalbuminemia. The diagnosis was confirmed by antibodies assay and endoscopy. The PTH level was less than 1 pg/l and radiography showed signs of hyperparathyroidism. Gluten-free diet, calcium and vitamin D led to an improvement of serum calcium.

[Cardiac manifestations of sickle cell disease]. / Les manifestations cardiaques de la drépanocytose.

In this study the authors report the cardiac complications seen in the course of sickle-cell disease. Among 41 homozygot patients the complications reported were as follow. Effort dyspnea in 15/32 (46% cases); systolic souffle in 36 patients (87.8% of cases); cardiomegaly in 30 patients (17% of cases) and electric abnormalities in 70% of cases. The echotomography practised in 27 cases was normal in 12 cases and showed a hyperkinetic aspect in 10 cases, a cardiomyopathy in four cases.

[A new case of relapsing hemolytic and uremic syndrome]. / A propos d'un nouveau cas de syndrome hémolytique et urémique a rechutes.

Relapsing hemolytic and uremic syndrome is infrequent in pediatric patients. The case of an infant who had HUS at 11 months of age and subsequently developed two relapses at 3 years and 3 1/2 years of age is reported. Outcome of the first episode was favorable, with no elements suggesting an increased risk for subsequent relapses. Conversely, the second and third episodes were followed by gradual deterioration of renal function and persistence of severe arterial hypertension. To clarify the epidemiology, clinical manifestations, histology, and outcome of HUS, the 24 pediatric cases of relapsing HUS reported in the English-language medical literature were reviewed. In this group, mean age at onset was 4 years 1 month (range 4 months-9 years) and number of relapses ranged from 1 to 14. Evidence of microangiopathy was the most common histologic finding (15/22) but non-specific lesions were seen in some instances. Opinions vary as to the prognosis of relapsing HUS; our case suggests that relapses are of adverse prognostic significance.