Home About us Contact
|
Home About us Contact | ||
|
|
||
Distilled Water (distilled + water)
Selected AbstractsEffects of crowding on populations of Aedes albifasciatus larvae under laboratory conditionsENTOMOLOGIA EXPERIMENTALIS ET APPLICATA, Issue 2 2000Raquel M. Gleiser Abstract Aedes (Ochlerotatus) albifasciatus (Macquart 1838) (Diptera: Culicidae) is a neotropical flood water mosquito, incriminated as the main vector of the western equine encephalitis virus, and which affects beef and milk production in central Argentina. The short time required to hatch and develop from egg to adult, usually in temporary pools, suggests a strategy which allows for exploitation of transient pools, thus evading predation and interspecific competition. Under these conditions intra specific competition could represent a major density-dependent source of larval mortality, but the relative importance of density-dependent regulation of mosquito populations has generated controversy. Therefore we examined the effects of larval density on basic population characteristics of Ae. albifasciatus in the laboratory. Larvae were obtained by synchronous hatching of eggs laid by field-trapped females. Emerging larvae (L1) were used to build cohorts of different initial densities, kept in plastic trays with 400 ml of distilled water, and food supplied daily during the first 10 days (0.1 g per larvae day,1). Age-specific development time and specific and relative mortality were estimated, and their relation to initial larval density was assessed through linear and non-linear regressions and correlation analysis. First hatching was registered 3 h after flooding the eggs. Higher levels of pre-adult mortality were detected in groups with higher densities. Specific mortality and average time to enter a stage of L1 to L3 could directly be related to initial larval density, but no significant relations were found for L4 and pupae. Results suggest that crowding could be a factor capable of regulating the density of natural populations of Ae. albifasciatus. [source] Citrate-mediated increase in the uptake of weathered 2,2-bis(p -chlorophenyl)1,1-dichloroethylene residues by plantsENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 3 2002Jason C. White Abstract Experiments were conducted to determine the ability of citrate to enhance the plant uptake of weathered 2,2-bis(p -chlorophenyl) 1,1-dichloroethylene (p,p,-DDE) from soil. Plots containing three rows of clover, mustard, hairy vetch, or rye grass were constructed in soils containing p,p,-DDE. On 11 occasions, the rows of each crop received water or sodium citrate (0.005 or 0.05 M). For each crop, there were significant reductions in p,p,-DDE concentration in the soil fractions (near root and rhizosphere) closely associated with the plant versus bulk soil. The roots of each crop accumulated 2 to 5 times more of the weathered contaminant (dry wt) than present in the bulk soil. Citrate (0.05 M) increased the concentration of p,p,-DDE in the roots of clover, mustard, and hairy vetch by 39% compared with vegetation that received water. In batch desorption studies, the release of weathered p,p,-DDE was significantly greater in the presence of 0.05 M citrate than in water. Citrate increased the extracted aqueous concentrations of five metal ions (Al, Fe, Ca, K, Mn) from soil by five- to 23-fold over distilled water. We hypothesize that citrate physically disrupts the soil through chelation of structural metal ions and release of bound humic material, facilitating p,p,-DDE availability and uptake by plants. [source] Surface Activation of a Ferrimagnetic Glass,Ceramic for Antineoplastic Drugs GraftingADVANCED ENGINEERING MATERIALS, Issue 7 2010Enrica Vernè A ferrimagnetic glass,ceramic, belonging to the system SiO2,Na2O,CaO,P2O5,FeO,Fe2O3, has been studied as potential carrier for antineoplastic agents, in order to exploit the combination of hyperthermia and chemotherapy. Different material pre-treatments, such as ultrasonic washing, water, or simulated body fluid dipping, were evaluated to promote the surface activation of the glass,ceramic, i.e., the hydroxyl groups formation on it. X-ray photoelectron spectroscopy, scanning electron microscopy, energy dispersion spectrometry, and wettability measurements were performed to observe the samples surface modification. The best results in terms of free hydroxyl groups exposition were obtained by dipping the samples in distilled water for 7 days at 37,°C. Two different anticancer drugs were selected in order to test the reactivity of the activated surface: cisplatinum and doxorubicin. The uptake and release of doxorubicin and cisplatinum were evaluated on glass,ceramic powders, by using UV,Visible spectrometry and graphite furnace atomic absorption spectroscopy, respectively. After 1 day of uptake at 37,°C, the quantity of doxorubicin incorporated into the glass,ceramic is 77,±,7 wt%, while only 42,±,9.6 wt% of cisplatinum is grafted onto the material surface. For both antitumoral agents, the maximum drug release after soaking in aqueous solutions at 37,°C was obtained in few hours, with a randomly distributed kinetics trend. [source] Influence of contamination on resin bond strength to nano-structured alumina-coated zirconia ceramicEUROPEAN JOURNAL OF ORAL SCIENCES, Issue 4 2010Shanchuan Zhang Zhang S, Kocjan A, Lehmann F, Kosma, T, Kern M. Influence of contamination on resin bond strength to nano-structured alumina-coated zirconia ceramic. Eur J Oral Sci 2010; 118: 396,403. © 2010 The Authors. Journal compilation © 2010 Eur J Oral Sci The purpose of this study was to evaluate the influence of contamination and subsequent cleaning on the bond strength and durability of an adhesive resin to nano-structured alumina-coated zirconia ceramic. Zirconia ceramic disks were coated with nano-structured alumina, utilizing the hydrolysis of aluminum nitride powder. After immersion in saliva or the use of a silicone disclosing agent, specimens were cleaned with phosphoric acid etching or with tap water rinsing only. Uncontaminated specimens served as controls. Plexiglas tubes filled with composite resin were bonded with a phosphate monomer [10-methacryloxydecyl-dihydrogenphosphate (MDP)]-containing resin (Panavia 21). Subgroups of eight specimens each were stored in distilled water at 37°C, either for 3 d without thermal cycling (TC) or for 150 d with 37,500 thermal cycles from 5 to 55°C. The tensile bond strength (TBS) was determined using a universal testing machine at a crosshead speed of 2 mm min,1. The topography of the debonded surface was scrutinized for fractographic features, utilizing both optical and scanning electron microscopy. The TBS to uncontaminated nano-structured alumina-coated zirconia ceramic was durable, while contamination significantly reduced the TBS. Phosphoric acid cleaning was effective in removal of saliva contamination from the coated bonding surface but was not effective in removal of the silicone disclosing agent. Nano-structured alumina coating improves resin bonding to zirconia ceramic and eliminates the need for air-abrasion before bonding. [source] Determination of elastic modulus of demineralized resin-infiltrated dentin by self-etch adhesivesEUROPEAN JOURNAL OF ORAL SCIENCES, Issue 1 2007Genta Yasuda The purpose of this study was to determine ultrasonically the changes in elastic modulus of demineralized adhesive-infiltrated dentin. Dentin disks were obtained from bovine incisors and shaped into a rectangular form. The specimens were immersed in single-step self-etch adhesives, then stored in distilled water and run through thermal cycles between 5 and 60°C. The longitudinal and shear wave sound velocities and the elastic modulus were determined using ultrasonic equipment composed of a pulser-receiver, transducers, and an oscilloscope. After 24 h of storage, the elastic modulus of mineralized dentin was 16.9 GPa and that of demineralized dentin was 2.1 GPa. The immersion of demineralized dentin in adhesives significantly increased the elastic modulus to 3.3,5.9 GPa. After 30,000 thermal cycles, the elastic modulus of dentin was 32.4 GPa, whereas that of demineralized adhesive infiltrated dentin was 3.1,4.1 GPa. Thermal stresses did not cause adhesive-infiltrated demineralized dentin to deteriorate, as measured by elastic modulus. [source] Physicochemical factors controlling the release of dissolved organic carbon from columns of forest subsoilsEUROPEAN JOURNAL OF SOIL SCIENCE, Issue 2 2002J.-M. Münch Summary Retention of dissolved organic carbon in soil depends on the chemical and physical environment. We studied the release of organic carbon from three carbonate-free forest subsoil materials (Bs1, Bs2, Bg) in unsaturated column experiments as influenced by (i) variations of the flow regime and (ii) varied chemical properties of the irrigation solution. We investigated the effect of flow initiation, constant irrigation, interruptions to flow, and variation in the effective pore water velocity on the release of organic C. The influence of ionic strength and cation valence in the irrigation solution was studied by stepped pulses of NaCl and CaCl2. The release of C from all materials was characterized by an initial large output and a decline to constant concentrations under long-term irrigation. Interrupting the flow increased its release when flow was resumed. The release from the Bs1 material was not related to the duration of the interruption. The Bs2 material, in contrast, released organic carbon in a way that was successfully described by a kinetic first-order model. Increased pore water velocity decreased the concentrations of C in the effluent from it. The pH of the irrigation solution had negligible effects on the mobilization of C. Increased ionic strength reduced the release, whereas rinsing with distilled water increased the concentrations of C in the effluent. The response of dissolved C to pulses of weak solutions, however, was sensitive to the type of cation in the previous step with strong solutions. The results suggest that the release of organic matter in the soils depends on its colloidal properties. [source] Influence of administration vehicles and drug formulations on the pharmacokinetic profile of lamotrigine in ratsFUNDAMENTAL & CLINICAL PHARMACOLOGY, Issue 5 2002M. M. Castel-Branco Abstract Given that administration vehicles and drug formulations can affect drug bioavailability, their influence on the pharmacokinetic profile of lamotrigine (LTG), a new-generation anti-epileptic drug, was studied in rats. Three different formulations administered intraperitoneally at a dose of 10 mg/kg were used: (1) LTG suspended in a 0.25% methylcelulose solution, (2) LTG dissolved in a 50% propylene glycol solution, and (3) LTG isethionate dissolved in distilled water. Plasma and brain homogenate levels were determined in order to evaluate vehicle-dependent drug absorption. The results demonstrated rapid absorption of LTG when it was administered as an aqueous solution, in contrast to a slower and more erratic absorption after the injection of either the lipophilic solution or the suspension. A plasma peak was achieved 15 min post-dose with the aqueous solution, with a brain peak being achieved 15 min later, while with the other formulations both plasma and brain homogenate peaks were reached 2 h after LTG administration. This study suggests that LTG isethionate dissolved in distilled water is the most suitable formulation for successful LTG pharmacokinetic studies in rats. [source] Neurochemical regulation of swallowing reflex in guinea pigsGERIATRICS & GERONTOLOGY INTERNATIONAL, Issue 1-2 2001Yu X Jia Background: Most peripheral afferent fibers involved in swallowing travel through the glossopharyngeal and vagus nerves and terminate in the nucleus of the tractus solitarius (NTS) and nodose ganglion (NG). Sensory neurons within the NTS and NG contain several neurotransmitters, including acetylcholine, histamine, serotonin and dopamine. The roles of these four neurotransmitters were investigated. Methods: The effects of atropine (muscarinic cholinergic receptor antagonist); pyrilamine maleate (PM, histamine H1 receptor antagonist); cimetidine (histamine H2 receptor antagonist); 8-hydroxy-2-(di- n -propylamino)-tetralin (8-OH-DPAT, specific 5-HT1A receptor agonist); and selective dopamine D1 receptor antagonist (Sch-23390) on the number of swallows elicited by distilled water in anesthetized guinea pigs were investigated. Results: Atropine (0.2 mg/kg) inhibited swallowing by approximately 70%; PM (30 mg/kg) inhibited swallowing by approximately 60%; cimetidine (30 mg/kg) inhibited swallowing by approximately 52.9% and Sch-23390 (chronic treatment) inhibited swallowing by approximately 40%. In contrast, 8-OH-DPAT did not alter the number of swallows. Chronic pretreatment of Sch-23390 markedly decreased the substance P (SP) content in the pharyngeal mucosa and the esophagus. Conclusion: These findings indicate that acetylcholine, histamine and dopamine are involved in the regulation of the swallowing reflex, whereas it is unlikely that serotonin is involved. [source] Experimental research of pool boiling heat transfer in horizontal narrow spacesHEAT TRANSFER - ASIAN RESEARCH (FORMERLY HEAT TRANSFER-JAPANESE RESEARCH), Issue 5 2004Enshen Long Abstract Much progress has been made in high-performance electronic chips, the miniaturization of electronic circuits and other compact systems recently, which brings about a great demand for developing efficient heat removal techniques to accommodate these high heat fluxes. With this objective in mind, experiments were carried out on five kinds of test elements with distilled water and ethanol as working liquids. The test elements used in these experiments consisted of five parallel discs with diameters varying from 5 mm to 40 mm. The experiments were performed with the discs oriented horizontally and uniform heat fluxes applied at the bottom surfaces. The influence of narrow spacing, space size, working liquid property, and heat flux on boiling heat transfer performance in narrow spaces has been investigated. Experimental results showed that the boiling heat transfer coefficient of a narrow space was 3 to 6 times higher than that of pool boiling when the narrow space size and heat flux combine adequately, but the critical heat flux was lower than that of pool boiling. © 2004 Wiley Periodicals, Inc. Heat Trans Asian Res, 33(5): 307,315, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/htj.20017 [source] SEM evaluation of root canal debridement with Sonicare CanalBrush irrigationINTERNATIONAL ENDODONTIC JOURNAL, Issue 5 2010M. I. Salman Salman MI, Baumann MA, Hellmich M, Roggendorf MJ, Termaat S. SEM evaluation of root canal debridement with Sonicare CanalBrush irrigation. International Endodontic Journal, 43, 363,369, 2010. Abstract Aim, To determine the efficacy of Sonicare CanalBrush irrigation for root canal cleaning. Methodology, Fifty human molar root canals were shaped with sequential NiTi rotary instruments up to size F3 (size 30, 0.09 taper; ProTaper system) and then enlarged apically with a Profile size 40, 0.04 taper. Five different irrigation protocols were tested (n = 10 canals per group) with 2 mL of distilled water (control, group I) or 2.5% NaOCl (control group II and test groups III, IV and V) between instrument size changes. Group III,IV received a final rinse with 17% EDTA for one min. This was extended by 30 s in group IV, whereas group V received this additional 30 s of 17% EDTA sonically dispersed with a Sonicare CanalBrush. For cleanliness evaluations, roots were split longitudinally, examined with scanning electron microscopy and scored according to Hülsmann et al. (1997) for debris and smear layer on the surface of the root canal wall. Walls were assessed at the coronal, middle and apical thirds. Data were analysed with the Kruskal,Wallis and Mann,Whitney tests. Results, Irrigation with 17% EDTA significantly reduced debris and smear layer scores (P < 0.05) compared to controls. The coronal and middle thirds had lower debris and smear layer scores than the apical third (P < 0.05). In all thirds, sonic agitation of the irrigant with a CanalBrush (group V) resulted in significantly cleaner canal walls compared to all other groups (P < 0.05). Conclusions, Irrigation by agitation with the Sonicare CanalBrush improved root canal debridement in the coronal, middle and particularly the apical thirds of the root canal. [source] Influence of tooth age and root section on root dentine dye penetrationINTERNATIONAL ENDODONTIC JOURNAL, Issue 12 2008A. Thaler Abstract Aim, To investigate dye permeability of root dentine according to patients' age, root section and dye penetration time. Methodology, A total of 96 extracted human single-rooted teeth, assigned to four age groups (<30, 30,45, 45,60 and >60 years) were separated at the cemento,enamel junction and root canals were enlarged. The root surfaces were coated with cyanocrylate to prevent external dye penetration and centrifuged in distilled water to eliminate air. For dye penetration the root canals were filled with methylene blue 5%. After 1, 30 and 60 days eight roots per age group were cross-sectioned in 1 mm slices. Dye penetrated areas and the complete dentine areas were digitized and measured. Differences between groups were judged with anova and LSD, P < 0.05 or P < 0.01. Results, The root section, the patients' age and the penetration time influenced significantly the penetrated areas (P < 0.05). After 1 and 30 days significant differences could be found only in the apical root sections between all age groups (P < 0.05). Dye penetration areas systematically decreased with increasing age and also from coronal to apical (P < 0.01). Conclusions, Age influenced dye penetration significantly. Dye penetration also depended on the location (coronal, middle and apical) within the root canal. These findings indicate that there may be a correlation between the tooth age and permeability of root dentine, which may influence the distribution and effectiveness of drugs used for root canal disinfection. [source] Radicular peroxide penetration from carbamide peroxide gels during intracoronal bleachingINTERNATIONAL ENDODONTIC JOURNAL, Issue 7 2008O. Gökay Abstract Aim, To evaluate and compare radicular peroxide diffusion from different concentrations of carbamide peroxide bleaching gels. Methodology, Fifty maxillary premolar teeth were separated into five groups (n = 10). Standardized endodontic access cavities were prepared in the occlusal surfaces, and the root canals were prepared using a step back technique and filled using the lateral compaction technique. The gutta-percha filling was removed 4 mm short of the cemento-enamel junction (CEJ) and a 2-mm-thick glass,ionomer cement base was placed. Outer root surfaces were sealed with wax and nail polish, leaving the coronal third of the tooth and the CEJ exposed. All teeth were immersed in a plastic tube containing 2 mL of distilled water, and the experimental groups were treated with a bleaching agent of either 10%, 17% or 37% carbamide peroxide (CP) or a mixture of 30% hydrogen peroxide (HP) and sodium perborate (SP) placed into the coronal pulp chamber of teeth and left for 24 h. Peroxide penetration was measured using the ferrothiocyanate method. Statistical analysis of data was conducted by using the Kruskal,Wallis Analysis of Variance and Mann,Whitney U test. Results, Higher peroxide penetration occurred with the 30% HP-SP mixture than with the CP bleaching gels, and the 37% CP group also promoted greater peroxide penetration than the other CP groups (P < 0.05). There was no statistically significant difference between 10% and 17% CP groups (P > 0.05). Conclusion, Peroxide penetration of CP gels was significantly lower than that of a HP-SP mixture. [source] Effect of bleaching agents on bonding to pulp chamber dentineINTERNATIONAL ENDODONTIC JOURNAL, Issue 4 2005S. Timpawat Abstract Aim, To determine the effect of intracoronal bleaching agents on adhesion of bonding agents to pulp chamber dentine. Methodology, Forty extracted human maxillary anterior teeth were randomly divided into four groups of 10 teeth each. Bleaching agents were sealed in pulp chambers for 7 days, as in clinical use. Group 1 (control): distilled water, group 2: 35% hydrogen peroxide, group 3: sodium perborate mixed with water, and group 4: sodium perborate mixed with 35% hydrogen peroxide. Teeth were stored in saline at 37 °C for 7 days. After the bleaching agent was removed, teeth were leached in water for a further 7 days prior to bonding. The crown was cut vertically from mesial to distal and the labial pulp chamber dentine was prepared for bonding with Clearfil SE-Bond and filled with resin composite (Clearfil AP-X). The bonded specimens were kept moist at 37 °C for 24 h. Microtensile bond strengths were determined using a universal testing machine. Additional teeth were prepared using the same bleaching procedures to investigate the scanning electron microscopic appearance of the dentine surface. Results, Mean values (±SD) of microtensile bond strength for the experimental groups were: group 1: 5.29 ± 2.21 MPa, group 2: 5.99 ± 1.51 MPa, group 3: 9.17 ± 1.65 MPa and group 4: 3.99 ± 1.31 MPa. Dentine treated with sodium perborate in water (group 3) had significantly higher mean bond strength when compared with the other three groups (P < 0.05, Tukey's test). Mean bond strength was lowest when dentine was treated with sodium perborate plus hydrogen peroxide (group 4). Conclusions, In terms of subsequent bond strength during restoration, sodium perborate mixed with distilled water appears to be the best intracoronal bleaching agent. [source] Evaluation of smear layer removal by EDTAC and sodium hypochlorite with ultrasonic agitationINTERNATIONAL ENDODONTIC JOURNAL, Issue 5 2002D. M. Z. Guerisoli Abstract Aim To evaluate smear layer removal by different irrigating solutions under ultrasonic agitation. Methodology Twenty recently extracted mandibular incisors with a single root canal were divided into four equal groups. Three groups were instrumented using the modified double-flared technique, the fourth remained unprepared. Each group was irrigated with either distilled water, 1.0% sodium hypochlorite alone or associated with 15% EDTAC between each file size. The final group was not instrumented but irrigated with 1.0% sodium hypochlorite and 15% EDTAC. A size 15 file energised by ultrasound was used with small amplitude filing movements against the canal walls in all groups. The teeth were split longitudinally and the roots measured to provide three sections of the same size (cervical, middle and apical). Samples were examined under the scanning electron microscope and assessed for the amount of smear layer by three independent and calibrated examiners. The scoring system ranged from 1 (no smear layer) to 4 (all areas covered by smear layer). Due to the non-parametric nature of the data, Friedman's test was used for statistical analysis. Results Canal walls were covered with smear layer in the group irrigated with 1% sodium hypochlorite alone and the group irrigated with distilled water. Canals irrigated with 1.0% sodium hypochlorite associated with 15% EDTAC had less smear layer throughout the canal (P < 0.001). There were no statistical differences for the amount of smear layer found on the cervical, middle and apical thirds when each group was analysed separately. Conclusions Under ultrasonic agitation, sodium hypochlorite associated with EDTAC removed the smear layer from root canal walls, whereas irrigation with distilled water or 1.0% sodium hypochlorite alone did not remove smear layer. [source] Penetration of propylene glycol into dentineINTERNATIONAL ENDODONTIC JOURNAL, Issue 4 2002E. V. Cruz Abstract Cruz EV, Kota K, Huque J, Iwaku M, Hoshino E. Penetration of propylene glycol into dentine. International Endodontic Journal, 35, 330,336, 2002. Aim This study aimed to evaluate penetration of propylene glycol into root dentine. Methodology Safranin O in propylene glycol and in distilled water were introduced into root canals with and without artificial smear layer. Dye diffusion through dentinal tubules was determined spectrophotometrically. The time required for dye to exit through the apical foramen using propylene glycol and distilled water as vehicles was also determined. The extent and areas of dye penetration on the split surfaces of roots were assessed using Adobe Photoshop and NIH Image Software. Results Propylene glycol allowed dye to exit faster through the apical foramen. The area and depth of dye penetration with propylene glycol was significantly greater than with distilled water (P < 0.0001). Smear layer significantly delayed the penetration of dye. Conclusion Propylene glycol delivered dye through the root canal system rapidly and more effectively indicating its potential use in delivering intracanal medicaments. [source] Apical extrusion of debris and irrigants using two hand and three engine-driven instrumentation techniquesINTERNATIONAL ENDODONTIC JOURNAL, Issue 5 2001C. C. R. Ferraz Abstract Aim To evaluate the weight of debris and irrigant volume extruded apically from extracted teeth in vitro after endodontic instrumentation using the balanced force technique, a hybrid hand instrumentation technique, and three engine-driven techniques utilizing nickel,titanium instruments (ProFile .04, Quantec 2000 and Pow-R). Methodology Five groups of 20 extracted human teeth with single canals were instrumented using one or other of five techniques: balanced force, hybrid, Quantec 2000, ProFile .04, or Pow-R. Debris extruded from the apical foramen during instrumentation were collected into preweighed 1.5 mL tubes. Following instrumentation, the volume of extruded irrigant fluid was determined by visual comparison to control centrifuge tubes filled with 0.25 mL increments of distilled water. The weight of dry extruded dentine debris was also established. Results Overall, the engine-driven techniques extruded less debris than the manual ones. However, there was no statistical difference between the balanced force technique and the engine-driven methods. The volume of irrigant extruded through the apex was directly associated with the weight of extruded debris, except within the ProFile group. The hybrid technique was associated with the greatest extrusion of both debris and irrigant. Conclusions Overall, the engine-driven nickel,titanium systems were associated with less apical extrusion. [source] Cleaning effectiveness of root canal irrigation with electrochemically activated anolyte and catholyte solutions: a pilot studyINTERNATIONAL ENDODONTIC JOURNAL, Issue 6 2000A. M. Solovyeva Abstract Aim The aim of this study was to evaluate the potential of electrochemically activated (ECA) anolyte and catholyte solutions to clean root canals during conventional root canal preparation. Methodology Twenty extracted single-rooted human mature permanent teeth were allocated randomly into four groups of five teeth. The pulp chambers were accessed and the canals prepared by hand with conventional stainless steel endodontic instruments using a double-flared technique. One or other of the following irrigants was used during preparation: distilled water, 3% NaOCl, anolyte neutral cathodic (ANC) (300 mg L,1 of active chlorine), and a combination of anolyte neutral cathodic (ANC) (300 mg L,1 of active chlorine) and catholyte. The teeth were split longitudinally and the canal walls examined for debris and smear layer by scanning electron microscopy. SEM photomicrographs were taken separately in the coronal, middle and apical parts of canal at magnification of ×800 to evaluate the debridement of extra-cellular matrix and at a magnification of ×2500 to evaluate the presence of smear layer. Results Irrigation with distilled water did not remove debris in the apical part of canals and left a continuous and firm smear layer overlying compressed low-mineralized predentine. All chemically active irrigants demonstrated improved cleaning potential compared to distilled water. The quality of loose debris elimination was similar for NaOCl and the anolyte ANC solution. The combination of anolyte ANC and catholyte resulted in improved cleaning, particularly in the apical third of canals. The evaluation of smear layer demonstrated that none of the irrigants were effective in its total removal; however, chemically active irrigants affected its surface and thickness. Compared to NaOCl, the ECA solutions left a thinner smear layer with a smoother and more even surface. NaOCl enhanced the opening of tubules predominantly in the coronal and middle thirds of canals, whereas combination of ANC and catholyte resulted in more numerous open dentine tubules throughout the whole length of canals. Conclusions Irrigation with electrochemically activated solutions cleaned root canal walls and may be an alternative to NaOCl in conventional root canal treatment. Further investigation of ECA solutions for root canal irrigation is warranted. [source] Moisture adsorption by milk whey protein filmsINTERNATIONAL JOURNAL OF FOOD SCIENCE & TECHNOLOGY, Issue 3 2002C. M. P. Yoshida Edible films, using whey protein as the structural matrix, were tested for water vapour diffusion properties. Whey protein films were prepared by dispersing 6.5% whey protein concentrate (WPC) in distilled water with pH kept at 7.0. Glycerol was the plasticizer agent. Film slabs (13.5 × 3.5 cm) were put in a chamber at 25 °C and 75% relative humidity, being held in vertical planes for different periods of time. The mass gain was determined throughout the experiment. We show that moisture adsorption by milk whey protein films is well described by a linear diffusion equation model. After an adsorption experiment was performed the solution of the diffusion equation was fitted to the data to determine the diffusion coefficient of the material. [source] Some characteristics of sperm motility in European hake (Merluccius merluccius, L., 1758)JOURNAL OF APPLIED ICHTHYOLOGY, Issue 5 2010A.-L. Groison Summary The objective of this paper is to characterize some of the sperm motility parameters in European hake (Merluccius merluccius), which is considered to be a species with aquaculture potential. The total ATP, ADP and AMP concentrations were determined using high-performance liquid chromatography on hake sperm samples collected during the winter-early spring in the Bay of Biscay (France) (n = 22) and on hake sperm samples collected during the summer-early autumn in waters off Western Norway (n = 5). The Adenylate Energy Charge (AEC) was deduced from these data. Computer Assisted Sperm Analysis (CASA) was used to measure a series of parameters characterizing the motility and the sperm swimming performances. Changes in salinity of the swimming medium affected all the measured motility parameters. The sperm velocity and the straightness of the movement were at maximum when sperm was activated with 100% filtrated sea water (100 SW) but decreased sharply later. When sperm was activated in filtrated sea water (50% diluted with distilled water: 50 SW) the values of these parameters increased (with a lower percentage of active cells) during the first 2.5 min and thereafter decreased slowly. In 50 SW, the initial velocity was lowered but the swimming period lasting 4.5 times longer than in 100 SW (but with a lower percentage of actively swimming cells). Initial sperm motility (percentage of swimming cells) in 100 SW was affected by sperm storage duration. Undiluted sperm could be stored at 4°C for 5 days and still show 13 ± 7% motility; the velocity and straightness of the movement were at maximum at the earliest period of measurement (0.5,1 day of storage) and then decreased gradually to reach their minima after 4 days of storage. Further, both the AEC and ATP content decreased with storage time, with the AEC decreasing from 0.78 ± 0.07 (mean ± SD) at stripping time to 0.20 ± 0.09 after 2 days of storage. Over the same period ATP content decreased from 85 ± 80 to 5 ± 4 nanomoles 10,9 spermatozoa, these data presenting a high variability. [source] Die-off of Cryptosporidium parvum in soil and wastewater effluentsJOURNAL OF APPLIED MICROBIOLOGY, Issue 1 2007A.M. Nasser Abstract Aims:, To determine the effect of biotic and abiotic components of soil on the viability and infectivity of Cryptosporidium parvum, and evaluate the suitability of viability tests as a surrogate for oocyst infectivity under various environmental settings. Methods and Results:, The die-off of C. parvum in saturated and dry loamy soil was monitored over time by immunofluorescence assay (IFA) and PCR to estimate oocysts viability and by cell culture to estimate oocysts infectivity. Pseudomonas aeruginosa activity resulted in digestion of the outer layer of the oocysts, as demonstrated by loss of the ability to react in IFA. Whereas, P. aeruginosa activity did not affect the DNA amplification by PCR. A 1-log reduction in the oocysts infectivity was observed at 30 °C in distilled water and in saturated soil while oocysts viability was unchanged. Incubation for 10 days in dry loamy soil at 32 °C resulted in a 3-log10 reduction in their infectivity while no change of oocysts viability was recorded. Conclusions:, Under low temperature, C. parvum oocysts may retain their infectivity for a long time. Soil desiccation and high temperatures enhance the die-off rate of C. parvum. Significance and Impact of the Study:, Previous die-off studies of C. parvum used viability tests that do not necessarily reflect the oocyst infectivity. Under low temperatures, there was an agreement observed between viability and infectivity tests and oocysts retained their infectivity for a long time. Desiccation and high temperatures enhance the loss of infectivity of C. parvum. The presented die-off data have significant implications on the management of wastewater reuse in warm environments. [source] Antibacterial polyvinyl chloride/antibiotic films: The effect of solvent on morphology, antibacterial activity, and release kineticsJOURNAL OF APPLIED POLYMER SCIENCE, Issue 4 2010Martha Merchan Abstract Medical-grade polyvinyl chloride was modified with sodium ampicillin in a concentration range from 0 to 5 wt % by solvent casting technique using cyclohexanone and N,N -dimethylformamide. The obtained polymeric systems were characterized by optical microscopy, tensile test, and scanning electron microscopy. In addition, in vitro antibacterial activity against Gram-negative and Gram-positive bacteria was determined by an agar diffusion test. Antibiotic release experiments were performed in distilled water and physiological saline solution, which were monitored by UV-vis spectroscopy. The results showed a crucial role of the solvent on the morphology, antibacterial activity, and releasing characteristic of the ampicillin. Furthermore, a mathematical model was applied to data obtained from release study, to characterize the release kinetics of the ampicillin from the polyvinyl chloride-antibiotic systems. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010 [source] Structure and properties of regenerated Antheraea pernyi silk fibroin filamentsJOURNAL OF APPLIED POLYMER SCIENCE, Issue 4 2009Baoqi Zuo Abstract Degummed Antheraeapernyi silk fibroin (APSF) fibers were dissolved in a lithium thiocyanate solution that was dialyzed against distilled water for 3 days. Solution-cast APSF films were dissolved in hexafluoroisopropanol to prepare a spinning solution. Wet spinning was employed to prepare APSF filaments. Scanning electron microscopy, X-ray diffraction, Fourier transform infrared spectroscopy, Raman spectroscopy, solid-state 13C cross-polarization/magic angle spinning nuclear magnetic resonance, and differential scanning calorimetry were employed to study the regenerated APSF filaments. The results showed a uniform distribution of molecular weights, and the largest one may have been greater than 200 kDa. The regenerated filaments contained ,-sheet, ,-helix, and random-coil conformations, and their breaking strength was 52.20% of the breaking strength of the native fibers. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009 [source] Polymerization of itaconic acid initiated by a potassium persulfate/N,N -dimethylethanolamine systemJOURNAL OF APPLIED POLYMER SCIENCE, Issue 5 2008S. J. Veli Abstract The synthesis and characterization of poly(itaconic acid) (PIA) with a novel initiator/activator system is presented. The initiator in this system was potassium persulfate, whereas the activator was N,N -dimethylethanolamine (DMEA). PIA was synthesized in distilled water and in 0.1M HCl at 40°C with reaction times of 72 and 96 h. PIA was investigated with differential scanning calorimetry, gel permeation chromatography, and pulse gradient spin echo-NMR and compared to the same polymer synthesized in dioxane with 2,2,-azobisisobutyronitrile as the initiator. It was shown that, despite the fact that some residual DMEA remained in the system, the properties of the PIA polymerized in the aqueous phase were very similar to the dioxane-synthesized polymer, which will enable a faster, cheaper, and environmentally more acceptable polymerization of itaconic acid. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 [source] Release behavior of freeze-dried alginate beads containing poly(N -isopropylacrylamide) copolymersJOURNAL OF APPLIED POLYMER SCIENCE, Issue 1 2008Jae-Hyung Choi Abstract Beads composed of alginate, poly(N -isopropylacrylamide) (PNIPAM), the copolymers of N -isopropylacrylamide and methacrylic acid (P(NIPAM- co -MAA)), and the copolymers of N -isopropylacrylamide, methacrylic acid, and octadecyl acrylate (P(NIPAM- co -MAA- co -ODA)), were prepared by dropping the polymer solutions into CaCl2 solution. The beads were freeze-dried and the release of blue dextran entrapped in the beads was observed in distilled water with time and pH. The degree of release was in the order of alginate bead < alginate/PNIPAM bead , alginate/P(NIPAM- co -MAA) bead < alginate/P(NIPAM- co -MAA- co -ODA) bead. On the other hand, swelling ratios reached steady state within 20 min, and the values were 200,800 depending on the bead composition. The degree of swelling showed the same order as that of release. Among the beads, only alginate/P(NIPAM- co -MAA- co -ODA) bead exhibited pH-dependent release. At acidic condition, inter- and intraelectrostatic repulsion is weak and P(NIPAM- co -MAA- co -ODA) could readily be assembled into an aggregate due to the prevailing hydrophobic interaction of ODA. Thus, it could block the pore of bead matrix, leading to a suppressed release. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 [source] Synthesis of poly(N,N -diethylacrylamide- co -acrylic acid) hydrogels with fast response rate in NaCl mediumJOURNAL OF APPLIED POLYMER SCIENCE, Issue 5 2008Hongliang Liu Abstract A series of thermo- and pH-sensitive poly (N,N -diethylacrylamide- co -acrylic acid) (P(DEA- co -AA)) hydrogels were prepared in NaCl aqueous solutions with different concentrations. Swelling and deswelling studies showed that in comparison with conventional P(DEA- co -AA) hydrogels (prepared in distilled water), the P(DEA- co -AA) hydrogels thus prepared had almost the same volume phase transition temperature (VPTT), but exhibited much faster response rates as the temperature was raised above their VPTT. Besides, the hydrogels prepared by this method had faster response rates in low pH buffer solutions, and the response rates increased with the increased concentration of the NaCl solutions used during the polymerization. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 [source] Preparation and characterization of interpenetration polymer network films based on poly(vinyl alcohol) and poly(acrylic acid) for drug deliveryJOURNAL OF APPLIED POLYMER SCIENCE, Issue 6 2008Yu-Mei Yue Abstract A series of full interpenetrating polymer network (full-IPN) films of poly(acrylic acid) (PAA)/poly (vinyl alcohol) (PVA) were prepared by radical solution polymerization and sequential IPN technology. Attenuated total reflectance-Fourier transform infrared spectroscopy, swelling properties, mechanical properties, morphology, and glass transition temperature of the films were investigated. FTIR spectra analysis showed that new interaction hydrogen bonds between PVA and PAA were formed. Swelling property of the films in distilled water and different pH buffer solution was studied. Swelling ratio increased with increasing PAA content of IPN films in all media, and swelling ratio decreased with increasing PVA crosslink degree. Tensile strength and elongation at break related not only to the constitution of IPNs but also to the swelling ratio of IPNs. Mechanical property of glutaraldehyde (0.5%) for poly(vinyl alcohol) crosslinking was better than that of glutaraldehyde (1.0%). DSC of the IPN films showed only a single glass transition temperature (Tg) for each sample, and Tg data showed a linear relationship with network composition. Morphology was observed a homogeneous structure, indicating the good compatibility and miscibility between PAA and PVA. Potential application of the IPN films in controlled drug delivery was also examined using crystal violet as a model drug. The release rate of the drug was higher at 37°C than 25°C for all IPNs and also increased slightly with decreasing of poly(acrylic acid) content. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 [source] Moisture absorption behavior of epoxies and their S2 glass compositesJOURNAL OF APPLIED POLYMER SCIENCE, Issue 6 2008Amit Chatterjee Abstract The influence of moisture exposure on the behavior of three toughened epoxy,amine systems (scrimp resins SC11, SC15, and SC79, Applied Poleramic, Inc., Benicia, CA) was investigated. Neat resin samples were conditioned by immersion in distilled water at 71°C and in an environmental chamber at 85% relative humidity and 87.8°C until saturation. The equilibrium weight gain ranged from 1.8 to 3.8% for the resins. The long-chain, low-crosslink-density epoxy system (SC11) absorbed the highest amount of water and was saturated first, and it was followed by the medium-crosslink-density (SC15) and high-crosslink-density materials (SC79). The moisture diffusivity decreased with the increasing crosslink density of the resins. The percentage reduction of the glass-transition temperature (Tg) at equilibrium moisture absorption was highest for the low-crosslink molecule. The percentage reductions for the medium-crosslink and higher crosslink systems were comparable. A net weight loss after drying was observed for the SC11 and SC79 resin systems. Fourier transform infrared analysis confirmed the segment breakage and leaching of molecules from the epoxy,amine network. The effects of moisture cycling on Tg were dependent on the epoxy,amine morphology. During the drying stage, Tg increased to a value higher than that of the unaged dry systems. The S2 glass composite samples were conditioned under identical conditions for the resin system. Composite systems absorbed less moisture than the neat resins as expected. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci 2008 [source] Preparation and characterization of silver containing chitosan fibersJOURNAL OF APPLIED POLYMER SCIENCE, Issue 6 2007Yimin Qin Abstract Silver containing chitosan fibers were prepared by blending fine particles of a silver sodium hydrogen zirconium phosphate compound into the spinning solution. It was possible to distribute the silver containing particles in the chitosan fiber because of the high viscosity of the spinning solution and the small diameter of the particles. Because the silver ions are imbedded inside the sodium hydrogen zirconium phosphate complex, the chitosan fibers remain white in color without being oxidized by the silver ions. The release of silver ions from the silver containing chitosan fibers were studied by placing the fibers in contact with distilled water, solution A, and aqueous protein solutions. Results showed that the release of silver ions was low in water, while in solution A and protein solutions, the silver ions are activated through ion exchange and chelation. The silver ions can significantly enhance the antimicrobial properties of the chitosan fibers. Experimental results showed that when placed in contact with the silver containing chitosan fibers, the reduction in bacteria count can be more than 98%. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 3622,3627, 2007 [source] Synthesis and properties of carboxymethyl cellulose- graft -poly(acrylic acid- co -acrylamide) as a novel cellulose-based superabsorbentJOURNAL OF APPLIED POLYMER SCIENCE, Issue 3 2007Aili Suo Abstract A new cellulose-based superabsorbent polymer, carboxymethyl cellulose- graft -poly(acrylic acid- co -acrylamide), was prepared by the free-radical grafting solution polymerization of acrylic acid (AA) and acrylamide (AM) monomers onto carboxymethyl cellulose (CMC) in the presence of N,N,-methylenebisacrylamide as a crosslinker with a redox couple of potassium persulfate and sodium metabisulfite as an initiator. The influences of reaction variables such as the initiator content, crosslinker content, bath temperature, molar ratio of AA to AM, and weight ratio of the monomers to CMC on the water absorbency of the carboxymethylcellulose- graft -poly(acrylic acid- co -acrylamide) copolymer were investigated. The copolymer's structures were characterized with Fourier transform infrared spectroscopy. The optimum reaction conditions were obtained as follows: the bath temperature was 50°C; the molar ratio of AA to AM was 3 : 1; the mass ratio of the monomers to CMC was 4 : 1; and the weight percentages of the crosslinker and initiator with respect to the monomers were 0.75 and 1%, respectively. The maximum water absorbency of the optimized product was 920 g/g for distilled water and 85 g/g for a 0.9 wt % aqueous NaCl solution. In addition, the superabsorbent possessed good water retention and salt resistance. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 1382,1388, 2007 [source] Chlorhexidine release and antibacterial properties of chlorhexidine-incorporated polymethyl methacrylate-based resin cementJOURNAL OF BIOMEDICAL MATERIALS RESEARCH, Issue 1 2010N. Hiraishi Abstract This study evaluated chlorhexidine release from experimental, chlorhexidine-incorporated polymethyl methacrylate (PMMA)-based resin cements prepared from Super-Bond C&B (Sun Medical) and examined the antimicrobial activity against Streptococcus mutans and Enterococcus faecalis. Chlorhexidine diacetate was added into PMMA polymer to obtain chlorhexidine concentration of 0.0, 1.0, 2.0, 3.0, and 4.0 wt %. Chlorhexidine-incorporated, cured resin disks were immersed in distilled water at 37°C for 5 weeks, and the chlorhexidine release was analyzed by high-performance liquid chromatography. The antibacterial effect of freshly mixed resin cements was examined using the agar diffusion test. For the direct contact test, the wells (n = 6) of microtiter plates were coated with cements. The coated wells were aged up to 3 weeks prior to the placement of bacterial suspensions directly on cured cements. The 3.0 and 4.0% chlorhexidine-incorporated cement exhibited chlorhexidine release for 5 weeks; however, more than 98% of chlorhexidine was retained in resin matrix. No release was detected from the 1.0 and 2.0% incorporated cement at 1 week and 2 weeks, respectively. The agar diffusion test failed to detect antibacterial effects against Enterococcus faecalis, whereas the direct contact test revealed the antibacterial effect of 3.0 and 4.0% incorporated cements against each microbe for 2 weeks. The 3.0 and 4.0% chlorhexidine-incorporated resin cement possessed prolonged chlorhexidine release and antibacterial properties for 2 weeks. © 2010 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2010 [source] | |||||||||||||||||||||||||