Carbon dioxide reforming of methane on Ni/CaO-AI2O3 catalysts

NiO/AI2O3 and NiO/CaO-AI2O3 samples were prepared and calcined at 700-900°C. Characterization of these samples was made using X-ray diffraction, low temperature nitrogen adsorption, thermal programmed reduction [TPR] and chemisorption of hydrogen at 700°C. The samples were reduced and the initial catalytic methane reforming activities were determined at 700°C. The crystalline phases in each catalyst and their domination as well as textural properties of the catalysts depend on the chemical composition and calcination temperatures. The thermal programmed desorption profiles and the chemisorption of hydrogen depend on the chemical composition of the catalysts and their calcinations temperature. Hydrogen chemisorption allowed the determination of important catalytic parameters which play dominant roles in determining the initial activity of these catalysts toward methane reforming to synthesis gas by carbon dioxide at 700°C

Purification of wet-process phosphoric acid by solvent extraction

High grade phosphoric acid can be obtained using liquid-liquid extraction technique. The influence of type of solvent, solvent concentration, organic/aqueous phase ratio, temperature, shaking time and phosphoric acid concentration on P2O5 extraction was studied. Scrubbing and stripping were also investigated, n-octanol proved to be the most efficient and selective. The temperature has a slight positive effect and the extraction was enhanced by increasing P2O5 and with the increase of organic/aqueous phase ratio. The stripping efficiency slightly increased with shaking time and the optimum organic/aqueous phase ratio was determined to be 2.0. For 9.2 M H3PO4, 99.90% of iron, 97.99% of fluoride and 99.99% of manganese were removed whereas complete removal of copper, cadmium and zinc was attained

hemodynamic effects and complications of tracheal intubation with intubating laryngeal mask airway: a comparison with direct laryngoscopy

The intubating laryngeal mask airway [ILMA] is designed to facilitate blind tracheal intubation. Direct laryngoscopy, to facilitate tracheal intubation, produces a marked pressor response. This randomized, controlled study -was undertaken to compare the complications of insertion and hemodynamic effects following tracheal intubation through intubating laryngeal mask airway [ILMA] with that of conventional Macintosh laryngoscope. One hundred adult patients undergoing elective surgery were randomly allocated into two equal-sized groups. All patients received general anesthesia using a standard balanced anesthesia technique. Tracheal intubation was performed using either intubating laryngeal mask airway or Macintosh laryngoscope. The intubation time, number of attempts required for successful intubation, the problems encountered during intubation, hemodynamic changes and postoperative pharyngolaryngeal complications were recorded. Time to intubation was comparatively longer in ILM.4 group than laryngoscopy group [58.6 +/- 8.2 sec. versus 29.2 +/- 5.6 sec. p <0.001]. The overall intubation success rate was comparable among the two study groups. The changes-in mean blood pressure were significantly less in ILMA group as compared to laryngoscope group [p <0.05]. The incidence of postoperative sore throat and hoarseness of voice was comparable among groups. Our results suggest that ILMA offers advantage over laryngoscope in minimizing the hemodynamic effects to intubation. Therefore, it can be used as a suitable alternative to laryngoscopy for tracheal intubation

Do antibiotic-coated central venous catheters reduce catheter-related bloodstream infection in intensive care patients?

Central venous catheters [CVCs] are a major cause of nosocomial bloodstream infections, which are difficult to control Catheters bonded with either antiseptics or antibiotics that constantly and slowly release antimicrobial substances are assumed to be beneficial in reducing rates of colonization and catheter-related infections. This prospective, randomized clinical trial was designed to evaluate the efficacy of catheters coated with either chlorhexidine and silver sulfadiazine [CHSS], or minocycline and rifampin [M/R] in reducing catheter-related colonization and bloodstream infections [CR-BSIs] in intensive care patients. 90 adult inpatients with CVCs, for 3 days or more, were conducted in this clinical trial [classified into three equal groups]. According to the type of the catheter, the patients were assigned to undergo insertion of triple lumen polyurethane CVCs either in standard version [unimpregnated] [Group I], or impregnated with either CHSS [on the extraluminal surface only] [Group II], or M/R [on the extraluminal and intraluminal surfaces] [Group III]. Microbiological evaluation was done for the insertion site before catheterization and at removal of the catheter, CVCs [tips and subcutaneous parts] and peripheral blood after removal of the catheter if accompanied by clinical signs of infection. 114 patients were assigned to undergo CVC insertion but dropouts with missing evaluation totalled 24 cases leaving 90 catheters with complete data and final microbiological evaluation. Clinical characteristics as well as clinical diagnoses of patients enrolled were similar in all study groups. Regarding colonization of the insertion site before catheterization, there were no significant differences between the three groups. Impregnated catheters showed a highly significant reduction in colonization of insertion site at removal of the catheter when compared to unimpregnated ones [P <0.001]. Impregnated catheters [groups II and III] were dramatically less likely to be colonized as unimpregnated version [group I] [4/30 [13.3%]; 2/30 [6.6%] vs. 10/30 [33.3%]]; respectively [P < 0.001]. Only one case of CR-BSIs [3.3%] was detected among catheters impregnated with CHSS vs. 4 cases [13.3%] among the unimpregnated ones. No cases of CR-BSIs [0%] were detected in the group of M/R-impregnated catheters. The use of CVCs coated with either M/R or CHSS is associated with a reduction in the rate of catheter colonization and catheter-related bloodstream infection compared to standard [uncoated] catheters in intensive care patients. In addition, the anti-infective efficacy of catheters impregnated with M/R was higher than that of catheters impregnated with CHSS

Adsorption of phenol and some substituted phenols on chemically - activated carbons developed from apricot stones

Chemically activated carbons were prepared from apricot stones. Phosphoric acid [25 - 75 wt%] was used as activating agent at 400 - 600 °C. Zinc chloride - activated carbons were also prepared at 600 °C and at 700 °C using zinc chloride [50 - 200 wt%] as activating agent. The textural parameters were determined from nitrogen adsorption data at 77 K. The chemistry of the carbon surfaces was determined from the FTIR spectrograms and from the base and acid neutralization capacities. The adsorption of phenol, p -nitrophenol and 3,5-dinitrophenol was carried out at 298 K for all the prepared carbons and also at 308 and 317 K for some selected carbons. Chemically - activated carbons exhibited high adsorption capacity towards phenols. Phenols adsorption increased with the increase of the molecular weight of the phenol and with the decrease of its solubility in water. The adsorption of phenols increased also with the decrease of the surface density of carbon - oxygen group existing. Adsorption of phenols proceeds via physical adsorption on oxygen - free surface and via chemisorption on oxygen contaminated carbon surfaces. Activated carbons [AC's] are widely used as adsorbents in decontamination process because of their extended surface area, microporous structure high adsorption capacity and special surface reactivity[1-4]. The surface of AC is considered heterogeneous from the point of view of both porosity and surface chemistry. The heterogeneity of the pore structure is a result of the existence of a wide range of size from a few to a few hundred angstroms[5]. The heterogeneity of the chemistry of AC is attributed to the existence of heteroatoms such as oxygen, nitrogen, hydrogen and phosphorous[6-7]. The heteroatoms, particularly oxygen, consist of organic functional groups at the edges of carbon crystallites. Carbon-oxygen groups include carboxyls, phenols, ethers, lactones and carbonyl[8]. There has been an increasing interest in the study of adsorption of organic molecules on AC. This is due to the importance of the removal of organic pollutants from water streams and the atmosphere[9]. Adsorption of aromatic compounds from solution, particularly phenols, has been studied extensively[10-14]. Phenolic compounds exist widely in the industrial effluents such as those from oil refineries, cool tar, leather, paint, pharmaceutical and steel industries. Since they are highly toxic and, in general, not amenable to biological degradation, methods of treatment are continuously modified and developed at all treatments. Among adsorbents, granular or powder AC proved to be the most efficient[15-19]. Regardless of the enormous studies undertaken concerning the adsorption of phenols on carbon, it can be seen that more intensive investigations still need to be undertaken to find convincing answer for some problems still remaining on phenol uptake by AC. The objective of this paper is to study the effect of surface chemistry and surface area of carbons on their adsorption of phenols. The samples are different from the point of view of the activating agent used [Zinc chloride and phosphoric acid]. An important feature common for all the samples is their acidic surface pH. Under such condition phenols exist in their molecular form. Three phenols were studied, namely phenol [P], paranitrophenol [PNP] and dinitrophenol [DNP]

Factors affecting aromatization functionality of n-heptane onto Cr[2]O[3]-Al[2]O[3] catalysts doped with K[2]O

CHROMIA/ALUMINA catalysts containing 2, 4, 8, 16 and 32 mol% Cr[2] O[3]. were prepared using the co-precipitation technique. Doping of the precipitated gels with 2 mol% K[2]O was made prior to calcinations at 500, 700 and 900 [degree sign] C. The structures of the calcinations products were determined from their XRD patterns and their textural properties were determined from the adsorption of nitrogen at 77 K. The dehydrocyclization of n-heptane was carried out at 520-580[degree sign] C. using helium as a gas carrier at a rate of 20-60 ml/min, in a pulse micro-reactor directly attached to a flame ionization detector. Samples containing 2 or 4 mol% Cr[2]O[3] did not show any crystalizied chromia phase, whereas those containing higher Cr[2]O[3] content showed gamma- and/or alpha- Cr[2]O[3] depending on their chromia content and calcination temperature. The surface area decreased and the pore size increased with increase of chromia content and with the rise of the calcinations temperature. Chromia/alumina catalysts calcined at 700 [degree sign] C exhibited the highest dehydrocyclization activities compared with the corresponding catalysts calcined either at 500 at 900 [degree sign] C. The conversion of n-heptane proceeded mainly via dehydrocyclization to toluene [major] and benzene [minor], with very low yield of cracking products of C[5]-naphthenes

Sol-gel synthesis of nanosized titanium phosphates

Alpha-titanium phosphate was prepared by three methods: Solid-solid reaction, Direct precipitation and Sol-gel methods. The produced samples were dried and characterized by using X-ray diffraction, IR spectra, thermal analysis and scanning electron microscopy. For the samples prepared by solid-solid reaction, a residual of unreacted materials was observed which disappeared by increasing the sintering temperature. The other two methods give a crystalline single phase of alpha-TiP. By increasing the refluxing time, the crystallinity of the samples improved. The IR results show the main absorption bands which characterized the phosphate compounds. Also, the IR patterns indicate that the TiP is coordinated as Ti-O-P-O-Ti and not TiO2 which coordinated as Ti-O-Ti. The thermal analysis indicates that the alpha-TiP underwent dehydration and it converted to alpha-TiP2O7 at high temperature. The characterization of the different samples indicates that the products depend on the method of preparation and on the controlled preparation

Pharmacological effects of tramadol hydrochloride on blood pressure and on some isolated smooth muscles of experimental animals

Tramadol is a centrally acting synthetic opioid analgesic drug. It is an effective analgesic with a good tolerable profile in short term uses. The apparent lack of tolerance and dependence and the low incidence of respiratory depression associated with tramadol suggests that the drug may offer advantages over some of the other established analgesic drugs currently used for relief of moderate to severe pain. This work was carried to investigate tramadol effect on some isolated and intact animal preparations. In in-vivo experiments: Intravenous injection of tramadol in anaesthetized cats at doses 0.6 and 1.2 mg/kg caused a significant rise of mean arterial blood pressure which was revealed to be through an alpha1 adrenoceptor agonistic action. However, higher doses of tramadol, [2.4 to 19.2 mg/kg] produced a biphasic change in mean arterial blood pressure; a significant initial decrease followed by a significant increase. The initial decrease in blood pressure was proved to be mediated through a peripheral site of action. Presynaptic alpha2 adrenoceptors were also involved in the decrease of blood pressure. The second phase [increase in blood pressure] was abolished in spinal cat preparation denoting a central site of action. Tramadol [2.4-19.2 mg/kg] also produced a dose dependent and significant decrease in heart rate. Using the cat nictitating membrane preparation showed that tramadol may act partially through inhibition of norepinephrine [NE] reuptake. The drug also significantly potentiated the NE induced contractions of isolated rabbit aortic spiral strip. This potentiation may be attributed to inhibition of NE reuptake. On isolated guinea pig tracheal spiral strip and ileal preparations, tramadol caused a dose depended reduction of the histamine induced contractions. However, the drug caused a significant increase in the height of the contractions of isolated rabbit jejunum. This stimulant action, was proved to involve both serotonergic and opioid receptors. It can be concluded that inspite of tramadol being one of synthetic opioid drugs, it did not show a histamine potentiating effect on the isolated guinea pig tracheal spiral strip. On the other hand it reduced the histamine induced contractions of the preparation which may be of value in patients with tendency to bronchoconstriction. The experiments carried on anaesthetized cats revealed that tramadol produced an elevation of blood pressure accompanied by bradycardia which must be considered especially in patients with cardiovascular disorders

Physiologic effects of pneumoperitoneum in adults with sickle cell disease undergoing laparoscopic cholecystectomy

Chronic hemolysis predisposes adults with sickle cell disease [SCD] to the formation of bilirubinate cholelithiasis. Cholecystectomy is the most frequent surgical procedure performed in SCD patients. Many studies have demonstrated the adverse consequences of pneumoperitoneum; however, few studies have examined the physiologic effects of pneumoperitoneum in adults with SCD during laparoscopic cholecystectomy [LC]. 40 ASA I-II patients, with cholelithiasis, scheduled for elective LC were randomly allocated into one of two equal groups: Group [1] normal patients without SCD [control group] and group [2] patients with SCD. In group [2] eleven patients [55%] were managed with a preoperative transfusion regimen to achieve a hemoglobin value of >/= 10g/dl, independent of hemoglobin S percentage. Study parameters [in the two groups] included heart rate/min, mean blood pressure [mmHg], PETCO[2], and Spo[2] at the following intervals: Before induction of anesthesia in the supine position [all except PETCO[2]], after anesthesia and before CO[2] insufflation in the supine position, 15, 30, 45, 60min after CO[2] insufflation in the anti-Trendelenburg position, at the end of CO[2] exsufflation in the supine position and 5min after the end of CO[2] exsufflation in the supine position. Arterial blood gases, to measure pH, PaCO[2] and PaO[2], were determined after induction of anesthesia and before CO[2] insufflation in the supine position, then 30min after CO[2] insufflation in the anti-Trendelenburg position, and 5min after the end of CO[2] exsufflation in the supine position. Statistical significance was established at p<0.05. Induction of anesthesia produced significant increase in HR in both groups. CO[2] insufflation led to additional increase in HR and persisted till abdominal deflation. As regards MAP, induction of anesthesia produced significant decrease in MAP in the two study groups. After CO[2] insufflation, MAP significantly increased from the baseline at 15, 30, 45, 60min and just before deflation in the anti-Trendelenburg position. CO[2] insufflation led to significant increase in ETCO[2] in the study groups to reach the maximum level just before abdominal deflation in the anti-Trendelenburg position. Five min later after deflation in the supine position, ETCO[2] decreased significantly. pH decreased significantly 30min after CO[2] insufflation in the anti-Trendelenburg position in both groups while PaCO[2] increased significantly 30min after CO[2] insufflation. Regarding SpO[2] and PaO[2], there were insignificant changes in the two study groups all over the time of the procedure. In group [2], none of the patients experienced vaso-occlusive crises or other SCD-related complications. There were no common bile duct injuries or deaths in the two study groups. The mean hospital stay in group [1], was 1.9 days [range, 1-3]. In group [2], nine patients [45%] were discharged on the 2[nd] postoperative day. The mean hospital stay, in this group, was 2.6 days [range, 2-4]. This study proved, beyond doubt, the safety of LC in patients with SCD and cholelithiasis. LC allows faster and safer postoperative recovery. A successful outcome can only be achieved by close consultation and mutual cooperation among surgeon, anesthesiologist, and hematologist

Fructose-induced insulin resistance and hypertension in rats: improvement by rilmenidine and safety of use with glibenclamide

Hypertension and insulin resistance are often part of a complex set of abnormalities including obesity, hyperlipidemia and glucose intolerance described as syndrome X. Besides a common genetic basis, insulin resistance and hypertension might be linked by excessive activity of the sympathetic nervous system. Accordingly suppression of this sympathetic overactivity might be an effective approach to reduce hypertension and the concomitant metabolic effect. Since central imidazoline receptors are currently considered to be a specific phamacological target for blood pressure reduction, a study was undertaken to determine the effects of rilmenidine, a centrally antihypertensive agent with selectivity for imidazoline I[1] receptors, in an animal model of hypertension associated with insulin resistance, i.e. rats fed on a high fructose diet. First the effect of fructose diet on body weight, blood pressure, glucose tolerance, fasting insulin level and lipid profile of experimental rats was determined and compared with those of normal rats. Then the effects of rilmenidine and/or glibenclamide were studied on these parameters. As insulin resistance is commonly a predisposing factor to endothelial dysfunction, we assessed the effect of fructose diet on the aortic reactivity to norepinephrine [NE]. The effect of that diet on the vasodilator response to acetylcholine, after NE-induced contractions, was also determined. In addition we investigated whether fructose-induced endothelial dysfunction is the result of impaired nitric oxide [NO] or prostanoid relaxing factors. This was achieved by comparing NE-evoked contraction or acetyl choline-induced relaxation of aortae, isolated from normal and fructose fed rats, before and after addition of N [G] nitro L arginine methyl ester [L-NAME] [a nitric oxide synthase inhibitor] or indomethacin [a cyclooxygenase inhibitor]. Then we assessed whether ATP sensitive K+ channels are involved in the fructose-induced endothelial dysfunction. This was done by demonstrating responses to either NE or acetyl choline before and after administration of glibenclamide [an ATP sensitive K+ cha vbnnel blocker]. Lastly, the effect of treating fructose fed rats with rilmenidine and/or glibenclamide, on the contractile response to NE and on acetyl choline-mediated relaxation of NE-induced tone, was determined. Body weight gain, hypertension. hyperinsulinemia and hyperlipidemia [significant increase in plasma cholesterol, triglycerides [TG], low density lipoprotein [LDL] level with decrease in high density lipoprotein [HDL] level] were noticed in the fructose than in normal rats. During the intraperitoneal glucose tolerance test, blood glucose levels in fructose fed rats were significantly raised relative to normal rats. Rilmenidine treatment not only lowered blood pressure, but also reduced body weight and decreased the plasma cholesterol level compared to fructose non-treated group. Moreover, the glucose tolerance was improved in the fructose rilmenidine-treated rats. No significant alterations in the insulin level or the other lipid profiles were elicited by rilmenidinc. In contrast glibenclamide pretreatment reduced glucose tolerance and increased plasma high density lipoproteins; otherwise all other aspects, studied in this work, were not significantly modified by the drug. Combined administration of rilmenidine and glibenclaniide did not show significant changes than those noticed with rilmenidine treatment alone except on glucose level. Improvement of the glucose tolerance in fructose fed rats treated with both rilmenidine and glibenclamide was found to be better than that observed in rilmenidine treated group alone. By examining the aortic endothelial functions, we observed that the contractile response to NE and the mean percentage relaxation to acetyl choline were decreased in the fructose fed rats than in normal animals. Administration of L-NAME augmented the NE-induced contraction and attenuated acetyl choline mediated relaxation in both groups [being more in the normal group than in the fructose fed group]. This suggests attenuation of both the spontaneously released NO and that released by acetyl choline in the fructose fed group, as a result of impairment of endothelial cell functions. Addition of indomethacin to aortae, isolated from normal and fructose fed rats, did not produce any difference in either NE contractile response or acetyl choline-induced relaxation of both groups; suggesting that prostanoids do not play a role in the fructose-induced endothelial dysfunction. In contrast when gibenclamide was added to NE or acetyl choline in the normal aortic preparations an increase of NE-induced contraction or a reduction in acetyl choline relaxant effect was observed. However glibenclarnide had no effect on aortic preparations isolated from fructose fed rats in response to either NE or acetyl choline. This indicates impairement of the ATP-activated K+ channels in the fructose mediated endothelial dysfunction. When fructose fed rats were treated with rilmenidine, whether administered alone [group 3] or combined with glibenciamide [group 4], a significant decrease in the contractile response to NE and a significant increase of acetyl cholineinduced relaxation was observed when compared to fructose fed non treated rats. The difference between both treated groups was found to be statistically insignificant. These results indicate that dlmenidine and not glibenclamide improved endothelial dysfunction. In contrast glibenclamide treated rats showed no significant improvement in the fructose-induced endothelial dysfunction. These data demonstrate that rilmenidine can ameliorate the deleterious effects of a high fructose diet. The beneficial effect of the drug is probably a result of reducing the sympathetic overactivity associated with insulin resistant syndrome, improving the metabolic effects accompanying the fructose diet as well as releasing endothelial derived relaxing factors as a result of alpha[2] adrenoceptor stimulation. Accordingly rilmenidine should be considered for the treatment of hypertension associated with metabolic disorders such as syndrome X. In addition glibenclainide therapy didn't modulate the effects of rilmenidine on the parameters studied in this work. So rilmenidine nay be of benefit in the treatment of insulin resistant hypertensive patients taking glibenclamide. However clinical investigations should be done before the assurance of this combination safety

Changes in thermal textural and acidic properties of alumina induced by surfactants

Alumina gels were precipitated in presence of nonionic, anionic and cationic surfactants. The gel was dried and calcined in the temperature range 400-800C. The textural and acidic properties of these thermal products were compared with the corresponding calcination products of pure alumina gel. Surfactants affected the thermal behavior of the gel, ionic surfactants being more effective. Textural changes resulted also in the thermal products of the gels precipitated in presence of surfactants at their critical micelle concentration [CMC]. Addition of cationic surfactants increased surface acidity whereas anionic surfactants resulted in an opposite effect

Conventional ultrasound and tissue characterization for breast masses

The primary attraction of ultrasound mammography is its ability to image breast repeatedly with no deleterious effects. In addition, papable breast masses can be conclusively determined to be fluid-filled or solid. Benign and malignant lesions can be further diagnosed. The major limitations of breast echography are the dependency of the technique on the sonographer as well as the complexity of the qualitative visual criteria for differentiation. A quantitative approach may thus be appreciated for eliminating these factors, enhancing the reproducibility and objectivity of a given breast echogram. A real-time data acquisition and analysis system has been developed employing image texture analysis system. A diagnostic database is used in classification of images according to the specific statistical parameters for each pathology in the database. The accuracy of the results is estimated by relating the case to the nearest statistical clusters representing the different pathologies in the database. Correction of the statistical parameters used in the analysis against shape, area, depth and angle of the selected region from transducer is also considered. Standardized frequency and time gain control are used for all cases. The overall accuracies for benign cases is 84 percent by normal echography and 89 percent by additional tissue analysis methods, while that for different malignancies is 86 percent by normal echography and 90.3 percent by tissue analysis

Surface properties of ethoxylated alkylphenol-formaldehyde polymeric surfactants

The surface and micellization properties of some low molecular weight ethoxylated alkylphenol-formaldehyde polymerize surfactants have been investigated. Surface tension as a function of concentration of the surfactant in aqueous solution was measured at 28, 38, 48 and 58 omicron using the Spinning Drop technique. From the least-squares regression analysis of data, values of the critical micelle concentration [CMC] the surface tension of the solution at the CMC [8 cmc] and the slope of the linear portion below the CMC [-d8/d log C] were determined. From these measurements, the maximum surface access concentration [gamma max] and the minimum area per molecule at the aqueous solution/air interface [Amim]2, the effectiveness [pi cmc] and the efficiency [Pc20] of these compounds in surface tension reduction were calculated

Surface and catalytic properties of chromia-alumina catalysts 1- Catalytic dehydrogenation of cyclohexane and methylcyclohexane

Chromia-alumina catalysts of different composition and calcination temperatures were prepared by different methods. The surface areas of the catalysts were calculated and the dehydrogenation activities towards cyclohexane and methylcyclohexane were measured. The kinetics of the dehydrogenation reactions were determined. The activity depends on the calcination temperature, method of preparation and chromia content. Cr3+ is considered as an active phase in the dehydrogenation reactions