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The benchmark of this study is to evaluate the antioxidant protective efficiency of Diosmin-Hesperidin combination, a natural citrus flavone of hesperidin derivative on heavy metals intoxication and Oxidative stress-induced damage in Wistar albino rats. Oral doses of diosmin-hesperidin in rats (200 and 100 mg/kg body weight, respectively) for a month (every other day) prior to heavy metals intoxication. Evaluation of the protective and antioxidant effects of the combination of diosmin and hesperidin, various Rt-PCR estimations, biochemical estimations, histopathological alterations as well as comet assay and caspase-3 activity for assessment of apoptosis were performed. Results indicated that heavy metals intoxication-induced decline in the levels of liver tissue P53 gene expression and increase of liver tissues of the apoptotic caspase-3 gene, also induced decline in the levels of liver tissue antioxidant parameters (SOD, GPx, and GSH), increased lipid peroxidation (MDA), DNA damage and apoptosis, these parameters were improved by pre-administration of diosmin+hesperidine. Diosmin+hesperidine dose (200 and100 mg/kg body wt. respectively) restored the p53 and caspase-3 genes near-normal values, antioxidant status to near normal and reduced lipid peroxidation, DNA, and tissue damage. These results were confirmed by histopathological examinations, which showed that pre-administration of diosmin+hesperidine protected the liver of albino rats against heavy metals intoxication-induced damage. Hence, it has been illustrated that diosmin+hesperidine might be an effective antioxidant and protector against heavy metals intoxication-induced damage in rats. Moreover, the diosmin+hesperidine alone pretreated group did not show any biochemical alterations, fold change of P53 or caspase-3 genes or DNA damage indicating the protective nature of the drug.

Aim. This study aimed to evaluate the antibacterial effect of sodium hypochlorite gel and four types of intracanal medicaments. Materials and Methods. The agar diffusion method was used to evaluate the antibacterial effect of five medicaments (sodium hypochlorite gel (NaOCl), chlorhexidine gel (CHX), calcium hydroxide paste (CH), Ledermix, and Diapex plus) against Enterococcus faecalis (E. faecalis), Staphylococcus aureus (S. aureus), and Escherichia coli (E. coli). The zone of inhibition around each medicament was measured in millimeters, after 48 hours of incubation at 37°C. The antibacterial effects of medicaments against each microbial strain and the sensitivity of microorganisms towards each medicament were compared using the one-way ANOVA and Games–Howell post hoc tests. The level of significance was set to p < 0.05 . Results. All medicaments showed variable inhibition zones for all bacterial strains except Diapex Plus which showed no antibacterial activity. NaOCl gel exhibited the most significant inhibition zones for all bacterial strains followed by CHX gel, Ledermix, and CH. However, the effect of CHX and CH paste against S. aureus was statistically similar, while the effect of CH against E. faecalis was significantly higher than the Ledermix. Conclusion. Sodium hypochlorite gel displayed the highest antibacterial activity among tested medicaments and can be recommended as a potent intracanal medicament. Chlorhexidine gel showed a significantly higher antibacterial effect when compared with Ledermix and calcium hydroxide. Calcium hydroxide demonstrated stronger antibacterial activity against E. faecalis than Ledermix. Diapex Plus exhibited no antibacterial effect.

Aim: The aim of this study was to compare the influence of two irrigation protocols and obturation techniques on the apical seal of three endodontic sealers. Materials and Methods: Crowns of 130 single-rooted teeth were cut and 10 roots were selected as controls, and the remaining roots were divided into four experimental groups (n = 30) according to the type of irrigation protocol and obturation technique. Each group was divided into three subgroups (n = 10) according to the type of root canal sealer. All root canals were prepared with size F4 Protaper Universal and irrigated with 3% sodium hypochlorite (NaOCl) + 3% hydrogen peroxide (H2O2) (Groups 1 and 3) or 3% NaOCl + 2% chlorhexidine (CHX) (Groups 2 and 4). Two gutta-percha obturation techniques were used: single-cone (Groups 1 and 2) and continuous wave (Groups 3 and 4) techniques. The following sealers were tested: MTA Fillapex (Subgroup A), AH Plus (Subgroup B), and Realseal SE (Subgroup C). The apical seal was assessed using dye penetration method, and the data were statistically analyzed. Results: In the first group, AH Plus showed the best apical seal (0.46 ± 0.098 mm), while RealSeal SE system showed the worst apical seal (3.47 ± 0.434 mm). In the second group, MTA Fillapex (0.58 ± 0.115 mm) and AH Plus (0.63 ± 0.109 mm) showed the best apical seal. In the third and fourth groups, all types of sealers showed similar high leakage patterns. Marked increase in the apical seal of RealSeal was observed in the third group (1.71 ± 0.453 mm). Conclusions: The type of irrigation protocol and obturation technique could affect the apical seal of tested sealers. When the single-cone technique was used, AH Plus with NaOCl + H2O2 and MTA Fillapex with NaOCl + CHX irrigation protocols showed significantly a high apical seal. RealSeal SE showed the worst apical seal when canals were irrigated with NaOCl/H2O2 and filled with the single-cone technique. All sealers showed inferior results when used with the continuous wave technique.

Background: Novel eco-friendly silver nanocomposites of xanthan/chitosan biguanidine hydrochloride polyelectrolyte complexes were successfully prepared. Methods: Silver nanoparticles (AgNPs) were formed through an insitu eco-friendly reduction by the non-toxic polysaccharides without the usage of toxic reagents. FTIR confirmed the successful preparation of the nanocomposites while XRD confirmed the presence of AgNPs with face-centered cubic structures. TEM confirmed the homogeneous distribution of AgNPs with an average size of 14.1 nm. SEM was used to study the surface morphology of the nanocomposites while the energy-dispersive X-ray spectroscopy (EDX) confirmed the presence of AgNPs. Results: Thermogravimetric analysis showed that the thermal stability was improved in the presence of AgNPs as detected from the calculated integral procedure decomposition temperature. Antibacterial activity against different bacteria species was significantly improved upon increasing the content of AgNPs. Conclusion: Due to their interesting properties, the prepared polyelectrolyte complexes and their AgNPs nanocomposites could be employed potentially in many biomedical applications like drug delivery.

The production of synergistically multi-acting cell wall hydrolyzing enzymes such as chitinase, glucanase, protease and whole cell-wall lytic enzymes “WCL” was highly observed in the culture filtrate of a strain molecularly characterized as Streptomyces rochei MZ227230. Enzymes productivity was monitored in different media and superiority of the modified lytic enzymes production medium (M4) was clearly noticed. Then the simultaneous optimization production of these enzymes through application of statistical modelling was conducted. Box-Behnken design (BBD) using the key components of M4 (C. albicans cell walls, baker yeast, chitin and peptone) followed by independent analysis for productivity of each enzyme helped to conduct four significant models describing four media that were specifically optimized to produce the utmost yields of chitinase (14.97), glucanase (27.89), protease (137.59) and WCL (65.28 U/ml). Pearson’s correlation analysis indicated the impossibility to potentiate the tested enzymes to the utmost yields simultaneously. However, the coproduction medium potentiated more than 80% of the maximal yields for all enzymes. Furthermore, the crude filtrate showed potent fungicidal effect against Fusarium graminearum, Mucor racemosus, Fusarium solani, and Candida albicans which should be attributed to its hydrolytic activity as indicated by the dose and time-dependent release of DNA, RNA and protein constituents of C. albicans

This research study was carried out during the two successive seasons of 2017/2018 and 2018/2019 at the farm located within the vicinity of the Arid lands Agriculture graduated studies and Research Institute (ALARI), Shobra Elkheima, Qalyobia governorate, Egypt, under an unheated plastic-house (25 m length x 9 m width x 3.5 m height). The experiments were laid out in a completely randomized design (CRD) with 3 replications, and the result data were subjected to analysis of variance (ANOVA). Chrysanthemum (Denderanthema grandiflora Ramat) cv. Zembla was employed in this research imported initially from DELIFLOR Company, in the Netherlands. Seedlings were planted in different substrate cultures to determine the most suitable local mixes for their cultivation and maximum production. Three of them were chosen from the local environment namely Water hyacinth, Palm fiber and Sugar-cane refuse in addition to Sawdust and Peat moss. The seedlings were planted into pots filled with eleven substrate culture mixes as follow: Water hyacinth (WH), WH + peat moss (1:1), Palm fibers (PF), PF + Peat moss (1:1), Coarse sawdust (CS), CS + Peat moss (1:1), Fine sawdust (FS), FS + peat moss (1:1), Sugar-Cane refuse (SC), SC + Peat moss (1:1) and Peat moss. The results indicated that the substrate combination of PF + peat moss (1:1) and WH + peat moss (1:1) gave higher significant values when compared to other remaining substrate with regards to vegetative parameters, i.e. plant height, stem diameter, number of leaves per plant and greenness of leaves as SPAD reading values. Also flower diameter exhibited a higher significant increase when PF + peat moss (1:1) + WH+ peat moss substrate combination was used compared to the other remaining substrates. Flower vase life also was influenced by the local substrate used in bringing up the cut-flowers and showed longer standing in the preservative solution when flowers were obtained from both of WH + peat moss (1:1) and Palm fiber + peat moss (1:1) compared to other substrate culture mixtures.

The effect of Pink Pigmented Facultative Methylotrophic (PPFM) bacteria as a bio-stimulant on vegetative growth, macro-nutrient elements ( N,P and K ) contents , chemical constituents and volatile oil percentage and components in rosemary plant (Rosmarinus officinalis L.) were studied during 2018 and 2019 seasons. Plant height (cm), number of lateral branches/plant, herb fresh & dry weights and root fresh & dry weights of rosemary plant were all greatly affected with all applied treatments of PPFM when compared with the control. The hugest effect was recorded by 1% PPFM bacteria spraying in both studied seasons. However, no significant effect was recorded due to PPFM applied treatments on P%. Highest values of total carbohydrates were recorded by both 1 and 3%. PPFM bacteria spraying in both studied seasons. Whereas, the highest values of C/N ratios were obtained with 3% PPFM in first season and 1% PPFM in the second one. A substantial effect from PPFM bacteria spraying was observed through its effect on reducing the level of NO3 and NO2 in rosemary herb when compared with the control. In any case, 3% of PPFM bacteria spraying was more effective than other treatments in recording the least values of NO3 and NO2 in first season compared to the control. Volatile oil % was enormously increased with 3% PPFM bacteria spraying in both studied seasons than other treatments or control. The main components of volatile oil of rosemary plant were Camphor, Eucalyptol, Verbenone, Borneol, Pinene, Pinanone, Bornyl acetate and Camphene. The treatments of PPFM bacteria spraying immensely stimulated the component % in volatile oil of rosemary herb than in the control. It could be concluded that the application of PPFM bacteria as foliar spraying in rosemary plant production had many advantages especially reducing NO3 and NO2 levels and increasing volatile oil % and volatile oil fractions not to mention it increased the percent of active ingredients.

PEROXIDASES have numerous important applications in industries and biodegradation of organopollutants , so there is a need to explore more and more sources of enzymes with different characteristics. In the present study, lignin peroxidases (LiPs) producing by fungus Humicola grisea were extracted and purified using gel filtration and ion exchange chromatography. Protein and heme protein were eluted in different peaks about 6 of these peaks had LiP activity and this is an indication that LiP in H. grisea was isoenzymes. Four of these isoenzymes were characterized regarding their molecular mass, optimum temperature and optimum pH for activity, substrate concentration and effect of some metal ions. The four purified isoenzymes have maximum activities at different temperatures, where optimum temperature for H2 and H4 isoenzyme were at 60 oC, and the optimum temperatures for H1 and H3 were at 40 oC and 30 oC, respectively. The maximum activities of the four isoenzymes were within the acidic range. The different LiP isoenzymes showed different Km and Vmax values representing the varied affinity of the four isoenzymes using veratryl alcohol as a substrate. Km values for H1, H2, H3 and H4 were 5.26, 5.0, 1.3 and 1.4, respectively. While Vmax values for the same isoenzymes were 1.25, 0.8, 0.87 and 1.1, respectively.

N ANOTECHNOLOGY, a highly promising discipline in science and technology, is the emerging and novel trend that will redesign the future of several existing know how which will change every aspect of our lives and leads to the generation of uniqueness in all the streams of technology. Biological synthesis of metal nanoparticles using microbes is gaining momentum due to the ecofriendly nature of the organisms which reduce toxic chemicals. Plant pathogenic fungi produce extracellular degradative enzymes that may be important in pathogenicity. Biosynthesis of silver nanoparticles was investigated using pathogenic Fusarium oxysporum f. sp. lycopersici and nonpathogenic strains of the same fungal species. These silver nanoparticles were characterized by means of UV–vis spectroscopy, transmission electron microscopy (TEM). UV–visible spectrum of the aqueous medium containing silver ion showed a peak at 420 nm corresponding to the Plasmon absorbance of silver nanoparticles. Transmission electron microscopy (TEM) micrograph showed formation of well-dispersed spherical silver nanoparticles with mean sizes 11.20 nm and 15.38 nm for pathogenic and nonpathogenic strains, respectively.

An accurate estimation of porosity and permeability are extremely essential for designing an ideal and efficient program of an oil and gas field development. Numerous methods have been developed to determine the porosity and permeability including laboratory measurements and log derived models. Artificial neural network (ANN) provides an efficient technique that successfully addressed several engineering and geological challenges. In the present study ANN is applied to help in predicting porosity and permeability in carbonate reservoirs using back propagation neural network (BPNN) with high accuracy on well log data from numerous fields worldwide. ANN has the ability to understand a highly non – linear relationship and to perform simulation studies in a rapid manner. The BPNN model of porosity and permeability is developed using a set of well logging data as input layers and core porosity and core permeability as output layers. Two scenarios are considered to develop by ANN. The first scenario considers using all available logging data directly as input for ANN. In the second scenario an additional input, diagenesis parameter, is added as input to ANN which is essentially calculated from logging data. In each scenario two models are developed; the first for porosity prediction and the second predicts permeability in carbonate reservoirs. The optimal learning rate and momentum constant used in the BPNN model are achieved after serial combinative trials. The available data was assigned 80% for training and 20% for verification. The results of the developed porosity and permeability models are well compared to core data in verification. In the first scenario, cross-plot of the actual porosity versus ANN predicted Porosity exhibited a good match with a correlation coefficient equal to 0.97. Cross-plot of the actual permeability versus ANN predicted permeability exhibited a good match with a correlation coefficient equal to 0.80. In the second scenario, cross-plot of the actual porosity versus ANN predicted porosity exhibited a good match with a correlation coefficient equal to 0.97. Cross-plot of the actual permeability versus ANN predicted permeability exhibited a good match with a correlation coefficient equal to 0.98. Such data indicate that the developed models are successful in predicting the porosity and permeability for carbonate reservoirs.

Background Fungi represent an interesting candidate for the synthesis of nanoparticles. The biosynthesis of silver nanoparticles (AgNPs) has many industrial and biomedical indications. We aimed in this work to biologically synthesize silver nanoparticles using Aspergillus niger and to evaluate its effect against the newly identified Allovahlkampfia spelaea that causes resistant human keratitis. Material and methods Aspergillus niger (soil isolate) was treated with silver nitrate to produce silver nanoparticles. AgNPs were characterized by Ultraviolet–Visible Spectroscopy, Transmission Electron Microscopy, and Fourier Transform Infrared Spectroscopy. The effect of the synthesized nanoparticles against Allovahlkampfia spelaea growth, encystation, excystation, and toxicity in host cells was evaluated. Results AgNPs exhibited significant inhibition of Allovahlkampfia spelaea viability and growth of both trophozoites and cysts, with a reduction of amoebic cytotoxic activity in host cells. Conclusion AgNPs may give a promising future to the treatment of Allovahlkampfia spelaea infections in humans.

Waste wool fibers (WF) were oxidized and ball milled to enhance the exchanging ability toward some metal ions, namely copper and zinc. Wool fibers were oxidized with hydrogen peroxide and tetra acetyl ethylene diamine, followed by grinding process. Optimization of the exchanging medium with regard to the metal ion concentration, pH, and exchanging time was performed. It was observed that the ability of the wool powder (WP) and oxidized wool powder (OWP) to exchange greater amount of metal ions than the ordinary waste wool fibers. Mostly, current results verify a significant ability of the OWP to exchange copper and zinc ions from their aqueous medium. Nevertheless, the ability of all wool substrates used to exchange copper is more than their ability to exchange zinc, and as the pH of the exchanging medium increases, the uptake % of both copper and zinc ions by WF or WP increases to reach its maximum at pH 6. The efficiency of WF, WP, or OWP to adsorb copper and zinc ions after a number of adsorpti...

Aim of the Study: The aim of this study was to compare the apical sealing ability of two single-cone filling materials when sealed with different types of root canal sealers. Materials and Methods: Eighty extracted maxillary and mandibular canines were selected and their crowns were cut. The root canals were prepared using ProTaper Universal rotary system until size F4 and then divided into seven experimental groups (n = 10 each) and two control groups (n = 5 each). Samples of Groups 1, 2, and 3 were filled with single-cone gutta-percha and AH Plus, MTA Fillapex, and EndoSequence BC, respectively. Samples of Groups 4, 5, and 6 were filled similar to the previous groups with the exception of using a single-cone CPoint. Samples of Group 7 were filled with cold gutta-percha lateral condensation technique. To assess apical microleakage, the apical linear dye penetration was measured microscopically and data were statistically analyzed. Results: All experimental groups showed significantly different dye apical leakage values (P = 0.000). No significant differences were found between Groups 1, 2, 4, 6, and 7 (P < 0.05). The lowest mean leakage value was observed in Group 6 (0.95 ± 0.56 mm) while Groups 3 (2.68 ± 0.71 mm) and 5 (2.61 ± 0.71 mm) showed significantly higher mean leakage values. Conclusions: The lowest apical leakage value was observed with single-cone CPoint/EndoSequence BC but without significant differences when compared with single-cone gutta-percha/AH Plus, single-cone gutta-percha/MTA Fillapex, single-cone CPoint/AH Plus, and lateral condensation technique. Higher apical leakage values were observed with single-cone gutta-percha/EndoSequence BC and CPoint/MTA Fillapex.

Cellulose nanocrystal (CNC) reinforced polycarbonate (PC) nanocomposites were obtained by melt extrusion. Highly concentrated CNC/PC masterbatch was first prepared using a dissolution/precipitation process which was then diluted by extrusion. Water from the CNC aqueous dispersion was exchanged to pyridine. PC was dissolved in this suspension and the mixture was precipitated in water. Two different methodologies were adopted for the PC matrix. In the first one, PC was submitted to the same dissolution/precipitation process than masterbatch, whereas in the second approach, the PC pellets were directly mixed with the solid masterbatch capsules. The structural, thermal and mechanical properties of ensuing nanocomposite materials were investigated.

Pressure core is the gold standard of reservoir saturation determination retaining gas and oil in an enclosed container preventing hydrocarbon loss to the mud system during retrieval of the core to surface. The technique is underutilized in the oil industry due to safety concerns, short coring lengths (3 to 7 feet) per trip and small core diameters (1.6 to 2.6 inches). A new elevated pressure coring system addresses these concerns. The system does not maintain true formation pressure but reduces the core barrel pressure to less than 1,000 psia for safer working conditions on surface. Upon arrival at surface, the core barrel and accompanying gas/liquid collection canisters are blown down and gas/liquid volumes measured and analysed. Free oil is gathered and stored for later analyses. Core diameter is 4 inches and core length is 10 feet. Zakum Development Company (ZADCO) operates a gas injection pilot in a large carbonate oil reservoir. There was a need to determine field remaining oil saturation after gas flood (ROSg) in a gas injection pilot. Pressure coring was selected as the best technology to obtain this data. This paper covers the planning and implementation of a successful elevated pressure coring operation in the U.A.E., the operational aspects, special core handling techniques, issues encountered and solved. Recommendations are made for future pressure coring operations. A follow up paper will cover the core and fluid analyses aspects.

Two hundreds and thirty catfish (Clarias lazera) weighing 200-250 gm each were obtained from abbasa fish farm were used in this investigation. LC50 of Copper Sulphate, lead acetate and Zinc sulphate was determined by exposure of the fish to different concentrations of the tested metals for 96 hours. It was 0.2, 0.1 and 0.1 ppm respectively. Determination of the residues of these heavy metals in the fish muscles and organs was studied after exposure of the fish to 0.02, 0.01 and 0.01 ppm (1/10 LC50) of the tested metals respectively. Blood picture, liver and kidney functions and some biochemical parameters were also studied after exposure of the fish to the tested salts of heavy metals. It was found that liver contains the highest amount of copper (Cu) and lead (Pb) 20.1 & 12.7 ppm respectively while zinc (Zn) was concentrated in the kidney (7.1 ppm). The muscles contained Cu, Pb & Zn (3.6, 0.3 and 0.4 ppm) respectively lower amounts than the permissible limits. RBCS count decreased by exposure of the fish to Cu, Pb and Zn (1.9, 1.95 and 1.5 million/ µl versus 2.4 for the control) respectively, Hemoglobin concentration and Packed Cell Volume (PCV) were also decreased. On the other hand total leucocytic count increased by the exposure of the fish to Cu and Pb (32.77 and 39.7 versus 27.3 103/µl), for the control. Exposure to Cu increased serum AST activity from 150 to 170 L whereas serum ALT, AP, total proteins, albumin, total bilirubin, cholesterol did not significantly altered by exposure to tested metals. Exposure to Cu and Pb increased serum glucose level from 90 to 115 and 100 mg/dI respectively, Cu decreased the sodium, chloride, potassium and calcium (123, 112, 2.4 m.mol /L and 6.9 mg/dl versus 140, 123,2.7 m.mol/L and 9.6 mg/dL versus 140, 123, 2.7 m.mol/L and 9.6 mg /dL) of the control respectively. On the contrary it increased blood urea nitrogen from 2.5 to 3.5 mg/dL. Exposure to lead and zinc did not significantly alter these parameters.

Lambda-cyhalothrin which is a recent pyrethroid insecticidal agent, elicited a concentration dependent negative inotropic and choronotropic effects on isolated perfused rabbit heart with an increase in coronary outflow which might be of cholinergic nature. A relaxant effect was achieved on the rat thoracic aortic strip preparations which was abolished in presence of atropine indicating the acetyl choline like effect of the compound. Lambda- cyhalothrin produced stimulatory effect followed by relaxation on rat phrenic nerve diaphragm preparation indicating the depolarizing neuromuscular blocking activity of the drug. A transient hypotensive effect was traced, the effect revealed the peripheral cholinergic effects of the compound. Moreover, spraying healthy rabbits with lambda- cyhalothrin for 5 successive days in an effective concentration (1mg/40 ml) did not produce any changes on the blood picture, liver and kidney functions. Meanwhile the compound sprayed in double effective concentration (2mg/40ml) induced a significant decrease in erythrocytes , leucocyte counts, Hb% and P. C. V. % with a significant prolonged prothrombin time after 14,21 and 28 days of last spray. It also elicited a significant elevation of SAST, SALT, alkaline phosphatase, serum bilirubin, blood urea nitrogen, creatinine and uric acid.

The kinetics of the isothermal decomposition of calcium maleate dihydrate (between 460 and 490°C) and calcium fumarate trihydrate (between 460 and 530°C) were studied. Kinetic measurements were carried out using the accumulatory method for the evolution of permanent product gases in a calibrated pre-evacuated glass apparatus. The product gases, from both reactants, were shown by mass spectrometry to be dominated by CO2 with relatively smaller amounts of CO, C2H2 and C2H4. The solid decomposition products, from both reactants, were identified using X-ray powder diffraction and IR spectroscopy as a mixture of CaCO3 and Ca(OH)2 together with carbonaceous residue. Due to the uncertainity of the composition of the solid residue, approximate reaction stoichiometry for the decomposition of both reactants is given. Analysis of kinetic data was somewhat complicated by the intervention of a secondary reaction possibly involving gaseous species. Kinetic data of both reactants were found to fit the zero-order equation in the range 0.05 < α < 0.47. Afterwards, data were best fitted to the second-order rate equation in the range 0.47 < α < 0.78. NMR analysis of partially decomposed calcium maleate showed no isomerization to the more stable fumarate anion. Scanning electron microscopy (SEM) revealed that neither of these two reactants underwent comprehensive melting during the decomposition reaction.

Cercariometric methods for monitoring the presence of schistosome cercariae in natural water systems have been unable to provide realistic data in a feasible manner. Apart from the task of filtering or centrifuging large volumes of water, the presence of suspended matter, plankton and debris has made visualisation and identification of the target organisms difficult. We have adapted a cercarial trap which utilised unsaturated fatty acids in a matrix of clear nail varnish, modified it by using locally available natural oils as stimulant and soft wax as the matrix and tested it under laboratory and field conditions in Sudan. The new system has potential for use in identifying important transmission foci.

Aim: The aim of this study is to compare the corono-apical sealing ability of three single-cone obturation systems using a glucose leakage model. Materials and Methods: A total of 90 extracted maxillary single rooted teeth were selected and their crowns were cut. The root canal of each sample was instrumented using a rotary crown down technique and then divided into four experimental (n = 20 each) and two control groups (n = 5 each). Samples in the experimental groups were filled as follows: Group 1, cold lateral condensation using Gutta-percha/AH Plus; Group 2, single-cone Gutta-percha and AH Plus; Group 3, single-cone Gutta-percha/and GuttaFlow2; Group 4, single-cone Resilon/RealSeal SE after 7 days, the sealing ability of root canal fillings was tested at different time intervals using glucose leakage model. Glucose leakage values were measured using a spectrophotometer and statistically analyzed. Results: The four experimental groups presented significantly different glucose leakage values at all test periods (P < 0.05). At the end of the observation period, the cumulative glucose leakage values of Groups 3 and 4 were significantly lower than those of Groups 1 and 2 (P < 0.05). Conclusion: Gutta-percha/GuttaFlow2 or Resilon/RealSeal SE combinations provided the superior sealing ability over the lateral condensation technique.

The kinetics of the thermal decomposition (473–510 K) of crystalline silver(I) squarate, Ag2C4O4, under reduced pressure in an accumulatory gas apparatus, have been studied for comparison with results obtained for the decompositions of the nickel(II) and copper(II) salts. No melting was observed and the overall products of decomposition were solid silver particles in a carbonaceous residue, pseudomorphic with the original reactant crystallites, and gaseous CO and CO2. The isothermal αvs. time curves were mainly deceleratory and approximated, for α < 0.5, to either the contracting-area or the contracting-volume rate equations, with an apparent activation energy of 190 ± 8 kJ mol–1. Silver oxide powder was found to catalyse the decomposition and this, together with the presence of CO2 in the gaseous products, led us to suggest that Ag2O is a reaction intermediate, which reacts further with product CO gas. This sequence of reactions in a solid-state decomposition and our failure to detect any recognisable reactant/product interface in electron microscopic studies of partially decomposed material are the central features of this study. The relationship between these results and those for silver oxalate and for nickel and copper squarates is discussed.

The thermal decomposition of copper(II) squarate dihydrate, in vacuum between 530 and 670 K, has been shown by kinetic and complementary analytical measurements to proceed (following rapid initial loss of the water of crystallization) through two reactions, involving stepwise reduction of the cation, Cu2+→ Cu+→ Cu0. This pattern of behaviour has been described previously for the decompositions of several copper(II) carboxylates. Isothermal fractional decomposition (α)vs. time curves were deceleratory throughout and were analysed in two parts. The first stage of reaction (α 0.5) was the decomposition of copper(I) squarate to copper metal produced in the form of small crystallites dispersed on a carbonaceous matrix that was pseudomorphic with the reactant particles. This process, studied in the interval 590–670 K, obeyed the first-order equation approximately, when due allowance was made for overlap of the two regions, and the activation energy was 210 ± 20 kJ mol–1. Electron microscopic observations of reactant, product and samples of partially decomposed salt did not reveal any recognizable reactant–product interface. It is suggested that Cu2O is formed as a decomposition intermediate, thus providing an explanation for the formation of product CO2. The observations are discussed and a reaction mechanism is proposed in the context of previous studies of the decompositions of copper(II) carboxylates and of other metal salts of squaric acid.

The effects of pre-irradiation with γ-rays on the isothermal decomposition kinetics of silver malonate have been studied quantitatively. Such pretreatment reduced the length of the induction period to the onset of reaction and increased the rate of subsequent salt breakdown, which has been shown to proceed by a nucleation-and-growth mechanism. Between 6.5 × 106 and 1.0 × 109 rad, the shapes of the isothermal, fractional-decomposition vs. time curves were unchanged as a result of irradiation and the increase in reaction rate was directly proportional to the γ-ray dose. It is concluded that pre-exposure to ionizing radiation increases the number of nuclei that are active in salt breakdown in direct proportion to the dose to which the sample had previously been exposed. The influence of radiation on the induction period is also discussed; the evidently greater reductions in length, for samples exposed to larger radiation doses, are attributed to radiation damage of the crystal, associated with the presence of radicals detected by an e.s.r. signal.