Penetration

Distribution by Scientific Domains
Distribution within Medical Sciences

Kinds of Penetration

  • allergen penetration
  • brain penetration
  • cell penetration
  • drug penetration
  • dye penetration
  • economic penetration
  • frost penetration
  • light penetration
  • limited penetration
  • market penetration
  • metal penetration
  • partial penetration
  • percutaneou penetration
  • peroxide penetration
  • poor penetration
  • root penetration
  • skin penetration
  • sperm penetration
  • tissue penetration
  • transdermal penetration

  • Terms modified by Penetration

  • penetration depth
  • penetration enhancer
  • penetration graph
  • penetration length
  • penetration rate
  • penetration resistance
  • penetration test
  • penetration time

  • Selected Abstracts


    PRODUCTIVITY AND THE PENETRATION OF INFORMATION TECHNOLOGY

    ECONOMIC PAPERS: A JOURNAL OF APPLIED ECONOMICS AND POLICY, Issue 4 2001
    HUW McKAY
    First page of article [source]


    EFFECT OF RAPID COOLING ON THE GROWTH AND PENETRATION OF SALMONELLA ENTERITIDIS INTO EGG CONTENTS

    JOURNAL OF FOOD SAFETY, Issue 4 2002
    HAIQIANG CHEN
    ABSTRACT Shell eggs were inoculated internally with approximately 10 cells of Salmonella enterica serovar enteritidis (S. enteritidis) and subjected to three different cooling treatments. Eggs were cooled from an initial temperature of 27C to approximately 7.2C. After cooling, eggs were stored at approximately 7.2C for 36 days, or stored at 5.7,9.5C for 30 days plus 6 days at 37C to simulate temperature abuse. Rapid cooling and subsequent storage of eggs at approximately 7.2C inhibited the growth of S. enteritidis in eggs. Slow cooling, and/or temperature abuse promoted growth of S. enteritidis in eggs. The penetration study indicated that rapid cooling and subsequent storage at 7.2C for 30 days did not affect the penetration of S. enteritidis into egg contents. The S. enteritidis isolated from the eggshell with shell membranes was significantly higher (P < 0.05) than from the internal egg contents, indicating that most of the S. enteritidis cells were trapped within the shell pores and/or shell membranes. [source]


    Sealing ability of occlusal resin composite restoration using four restorative procedures

    EUROPEAN JOURNAL OF ORAL SCIENCES, Issue 6 2008
    Danuchit Banomyong
    The purpose of this work was to investigate fluid flow after restoration using four restorative procedures. Micro-gap, internal dye leakage, and micropermeability of bonded interfaces were also investigated. Each tooth was mounted, connected to a fluid flow-measuring device, and an occlusal cavity was prepared. Fluid flow after cavity preparation was recorded as the baseline measurement, and the cavity was restored using one of four restorative procedures: bonding with total-etch (Single Bond 2) or self-etch (Clearfil SE Bond) adhesives without lining; or lining with resin-modified glass-ionomer cement (GIC) (Fuji Lining LC) or conventional GIC (Fuji IX) and then bonding with the total-etch adhesive. Fluid flow was recorded after restoration and at specific time-points up to 6 months thereafter and recorded as a percentage. Micro-gap formation was analyzed using resin replicas and scanning electron microscopy. Internal leakage of 2% methylene blue dye was observed under a light microscope. In micro-permeability testing, fluorescent-dye penetration was investigated using confocal laser microscopy. None of the restorative procedures provided a perfectly sealed restoration. Glass-ionomer lining did not reduce fluid flow after restoration, and micro-gaps were frequently detected. The self-etch adhesive failed to provide a better seal than the total-etch adhesive, and even initial gap formation was rarely observed for the former. Penetration of methylene blue and fluorescent dyes was detected in most restorations. [source]


    Electronic Contact Deposition onto Organic Molecular Monolayers: Can We Detect Metal Penetration?

    ADVANCED FUNCTIONAL MATERIALS, Issue 13 2010
    Hagay Shpaisman
    Abstract Using a semiconductor as the substrate to a molecular organic layer, penetration of metal contacts can be clearly identified by the study of electronic charge transport through the layer. A series of monolayers of saturated hydrocarbon molecules with varying lengths is assembled on Si or GaAs and the junctions resulting after further electronic contact is made by liquid Hg, indirect metal evaporation, and a "ready-made" metal pad are measured. In contrast to tunneling characteristics, which are ambiguous regarding contact penetration, the semiconductor surface barrier is very sensitive to any direct contact with a metal. With the organic monolayer intact, a metal,insulator,semiconductor (MIS) structure results. If metal penetrated the monolayer, the junction behaves as a metal,semiconductor (MS) structure. By comparing a molecule-free interface (MS junction) with a molecularly modified one (presumably MIS), possible metal penetration is identified. The major indicators are the semiconductor electronic transport barrier height, extracted from the junction transport characteristics, and the photovoltage. The approach does not require a series of different monolayers and data analysis is quite straightforward, helping to identify non-invasive ways to make electronic contact to soft matter. [source]


    Variations in Hole Injection due to Fast and Slow Interfacial Traps in Polymer Light-Emitting Diodes with Interlayers

    ADVANCED FUNCTIONAL MATERIALS, Issue 1 2010
    M. James Harding
    Abstract Detailed studies on the effect of placing a thin (10,nm) solution-processable interlayer between a light-emitting polymer (LEP) layer and a poly(3,4-ethylenedioxythiophene)/poly(styrenesulfonic)-acid-coated indium tin oxide anode is reported; particular attention is directed at the effects on the hole injection into three different LEPs. All three different interlayer polymers have low ionization potentials, which are similar to those of the LEPs, so the observed changes in hole injection are not due to variations in injection barrier height. It is instead shown that changes are due to variations in hole trapping at the injecting interface, which is responsible for varying the hole current by up to two orders of magnitude. Transient measurements show the presence of very fast interfacial traps, which fill the moment charge is injected from the anode. These can be considered as injection pathway dead-ends, effectively reducing the active contact surface area. This is followed by slower interfacial traps, which fill on timescales longer than the carrier transit time across the device, further reducing the total current. The interlayers may increase or decrease the trap densities depending on the particular LEP involved, indicating the dominant role of interfacial chain morphology in injection. Penetration of the interlayer into the LEP layer can also occur, resulting in additional changes in the bulk LEP transport properties. [source]


    Penetration of propylene glycol into dentine

    INTERNATIONAL ENDODONTIC JOURNAL, Issue 4 2002
    E. 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]


    An in vitro comparison of three thermal gutta percha systems

    INTERNATIONAL ENDODONTIC JOURNAL, Issue 4 2001
    M. P. Horrocks
    Aim,The aim of this study was to compare the ability of three contemporary obturation techniques to resist microleakage, using root canals prepared in extracted single rooted teeth by a standardized method. Methodology,The shaping technique involved the use of tapered nickel titanium rotary files to create a uniform 0.08-mm/mm taper. Six groups were compared, two representing control groups, a third group being obturated with a warm vertical condensation technique, a fourth group by an injection thermoplasticized system, a fifth group with a thermomechanical compaction method and a sixth group using cold lateral condensation. A zinc oxide/eugenol sealer was used as the sealant in all the obturation procedures. Forty-six extracted teeth were used in the study, three teeth in each control group and 10 teeth in each of the remaining four groups. Microleakage was compared using dye leakage with Indian ink. Penetration of the dye at the gutta percha/dentine interface was visualized after the root had been rendered transparent. Dye leakage was then measured from four aspects with the use of a stereomicroscope and export of a digital image to a software package, to facilitate accurate assessment of dye penetration. Two parameters were measured for each sample, the mean dye penetration and maximum dye penetration. Results,The mean values for linear dye leakage in the thermomechanical compaction group was 0.53 mm, the warm vertical condensation group was 0.73 mm, the injection thermoplasticized group was 0.15 mm and the cold lateral condensation group was 0.53 mm. There was no statistical difference between the means of the different groups (P > 0.05). The mean of the maximum values for dye leakage in the thermomechanical compaction group was 0.65 mm, the warm vertical condensation group was 1.02 mm, the injection-thermoplasticized group was 0.28 mm and the cold lateral condensation group was 0.74 mm. There was no statistical difference between the means of the different groups (P > 0.05). Conclusions,Within the conditions of this study, there was no statistical difference between the different groups with respect to either mean or maximum dye leakage. [source]


    Targeted delivery of salicylic acid from acne treatment products into and through skin: role of solution and ingredient properties and relationships to irritation

    INTERNATIONAL JOURNAL OF COSMETIC SCIENCE, Issue 4 2004
    L. Rhein
    Salicylic acid (SA) is a beta-hydroxy acid and has multifunctional uses in the treatment of various diseases in skin such as acne, psoriasis, and photoaging. One problem often cited as associated with salicylic acid is that it can be quite irritating at pH 3,4, where it exhibits the highest activity in the treatment of skin diseases. We have identified strategies to control the irritation potential of salicylic acid formulations and have focused on hydroalcoholic solutions used in acne wipes. One strategy is to control the penetration of SA into the skin. Penetration of the drug into various layers of skin, i.e. epidermis, dermis, and receptor fluid, was measured using a modified Franz in vitro diffusion method after various exposure times up to 24 h. A polyurethane polymer (polyolprepolymer-15) was found to be an effective agent in controlling delivery of SA. In a dose-dependent fashion it targeted delivery of more SA to the epidermis as compared to penetration through the skin into the receptor fluid. It also reduced the rapid rate of permeation of a large dose of SA through the skin in the first few hours of exposure. A second strategy that proved successful was incorporation of known mild nonionic surfactants like isoceteth-20. These surfactants cleanse the skin, yet due to their inherent mildness (because of their reduced critical micelle concentration and monomer concentration), keep the barrier intact. Also, they reduce the rate of salicylic acid penetration, presumably through micellar entrapment (either in solution or on the skin surface after the alcohol evaporates). Cumulative irritation studies showed that targeting delivery of SA to the epidermis and reducing the rapid early rate of penetration of large amounts of drug through the skin resulted in a reduced irritation potential. In vivo irritation studies also showed that the surfactant system is the most important factor controlling irritancy. SA delivery is secondary, as formulations with less SA content reduced the rate of delivery to the receptor and yet were some of the most irritating formulations tested, presumably due to the action of the specific anionic surfactant on the barrier. Alcohol content also did not appreciably affect irritation and SA delivery; formulations with considerably low alcohol content but containing anionic versus nonionic surfactant systems exhibited considerably higher irritancy. Thus the surfactant type was again the predominant factor in those studies, although arguably alcohol plays some role (solubilization of SA). Results showed that both polymers and mild surfactants work in concert to provide the optimal formulation benefits of targeted delivery and reduced irritation. Synergistic relationships among hydroalcoholic formulation components will be discussed along with the mechanisms likely involved in controlling delivery of SA to skin. [source]


    Development of axonal pathways in the human fetal fronto-limbic brain: histochemical characterization and diffusion tensor imaging

    JOURNAL OF ANATOMY, Issue 4 2010
    Lana Vasung
    Abstract The development of cortical axonal pathways in the human brain begins during the transition between the embryonic and fetal period, happens in a series of sequential events, and leads to the establishment of major long trajectories by the neonatal period. We have correlated histochemical markers (acetylcholinesterase (AChE) histochemistry, antibody against synaptic protein SNAP-25 (SNAP-25-immunoreactivity) and neurofilament 200) with the diffusion tensor imaging (DTI) database in order to make a reconstruction of the origin, growth pattern and termination of the pathways in the period between 8 and 34 postconceptual weeks (PCW). Histological sections revealed that the initial outgrowth and formation of joined trajectories of subcortico-frontal pathways (external capsule, cerebral stalk,internal capsule) and limbic bundles (fornix, stria terminalis, amygdaloid radiation) occur by 10 PCW. As early as 11 PCW, major afferent fibers invade the corticostriatal junction. At 13,14 PCW, axonal pathways from the thalamus and basal forebrain approach the deep moiety of the cortical plate, causing the first lamination. The period between 15 and 18 PCW is dominated by elaboration of the periventricular crossroads, sagittal strata and spread of fibers in the subplate and marginal zone. Tracing of fibers in the subplate with DTI is unsuccessful due to the isotropy of this zone. Penetration of the cortical plate occurs after 24,26 PCW. In conclusion, frontal axonal pathways form the periventricular crossroads, sagittal strata and ,waiting' compartments during the path-finding and penetration of the cortical plate. Histochemistry is advantageous in the demonstration of a growth pattern, whereas DTI is unique for demonstrating axonal trajectories. The complexity of fibers is the biological substrate of selective vulnerability of the fetal white matter. [source]


    Penetration of nanoparticles and nanomaterials in the skin: Fiction or reality?

    JOURNAL OF PHARMACEUTICAL SCIENCES, Issue 1 2010
    Biancamaria Baroli
    Abstract The advent of nanotechnological products in the market, while holding great promise, is raising concerns in consumers. Therefore, this contribution will attempt to compare different particulate formulations and to answer whether their passive penetration into, and potential permeation through the skin may be possible or not. To this end, skin structure, composition, and penetration paths will be concisely reviewed. Parameters generally cited to affect skin absorption will be resumed and commented on from the perspective of potentially penetrating nanosized agents. These sections will provide the basis to understand what is fiction and what is reality. © 2009 Wiley-Liss, Inc. and the American Pharmacists Association J Pharm Sci 99:21,50, 2010 [source]


    Mixing calcium chloride with commercial fungicide formulations results in very slow penetration of calcium into apple fruits

    JOURNAL OF PLANT NUTRITION AND SOIL SCIENCE, Issue 3 2004
    Thomas K. Schlegel
    Abstract Foliar applications of calcium salts are usually combined with fungicides. In the years 2002 and 2003, it was tested if this practice assures high rates of penetration of calcium. Amounts that penetrated in 24 h were measured at 20,°C using 45CaCl2. To ensure maximum penetration rates, humidity was maintained at 100,%. Sample size was 40 to 50 fruits, and data were presented as box plots because distribution of data was not normal. Median rates of penetration of CaCl2, measured with mixtures of fungicides and CaCl2 at 5 or 10 g l,1, respectively, were very slow, and amounted to only a few percent of the dose applied. Rates were a little higher with very young fruits (55 days after full bloom, DAFB). Adding alkyl polyglycoside surfactants at 0.2 g l,1 significantly decreased surface tensions, and increased rates of penetration by up to 15-fold. Still, total penetration of CaCl2 rarely exceeded 20,% of the dose applied (median penetration), even in the presence of an additional surfactant. In all treatments, outliers with 60 to 100,% penetration in 24 h occurred, and this was attributed to penetration into lenticels. This is expected to result in unequal concentrations of calcium in fruits, especially in the sub-epidermal layers. Addition of a suitable surfactant to mixtures of fungicides with CaCl2 is strongly recommended as it enhances wetting and greatly increases penetration rates of CaCl2. Mischen von Calciumchlorid mit Fungiziden resultiert in einer sehr langsamen Penetration von Calcium in Apfelfrüchte Zur Blattdüngung werden Calciumsalze meist mit Fungiziden gemischt. Es wurde untersucht, ob diese Praxis hohe Penetrationsraten für das ausgebrachte Calciumsalz gewährleistet. Die Penetration wurde mit 45CaCl2 bei 20,°C gemessen. Die Luftfeuchte betrug 100,%, so dass maximale Penetrationsraten erzielt wurden. Der Stichprobenumfang betrug 40 bis 50 Früchte. Die Ergebnisse werden als Box-Plots präsentiert, weil die Verteilung der Daten nicht normal war. Bei Mischungen von CaCl2 (5 bis 10 g l,1) mit Fungiziden betrugen die Mediane der Penetrationsraten von CaCl2 nur einige Prozent. Bei sehr jungen Früchten (55 Tage nach Vollblüte, DAFB) waren die Raten etwas höher als bei älteren. Durch Zugabe von Alkyl-Polyglykosiden (0.2 g l,1) wurden die Oberflächenspannungen der Lösungen verringert und die Penetration von Calcium bis zu 15fach erhöht. Trotzdem betrug die Penetration in 24 h nur selten mehr als 20,% der Dosis. In allen Behandlungen wurden Ausreißer beobachtet, bei denen die Penetration in 24 h 60 bis 100,% der Dosis betrug. Das wurde auf Infiltration von Lentizellen zurückgeführt. Dadurch dürfte die Calciumkonzentration in Früchten nach Spritzung mit CaCl2 nicht homogen sein, besonders nicht in den subepidermalen Schichten. Die Zugabe eines geeigneten Netzmittels zu Mischungen von Fungiziden mit CaCl2 wird empfohlen. Dadurch wird die Benetzung der Früchte verbessert, und die Penetrationsraten werden erhöht. [source]


    EFFECT OF LACTIC ACID AND LACTIC ACID BACTERIA TREATMENT ON MYOFIBRILLAR PROTEIN DEGRADATION AND DYNAMIC RHEOLOGY OF BEEF

    JOURNAL OF TEXTURE STUDIES, Issue 3 2007
    M. SIGNORINI
    ABSTRACT Lactic acid has been used as an efficient decontaminant in meats aimed for direct consumption or product fabrication. However, reports on the functionality of proteins extracted from lactic acid-treated meat are scattered. The objective of this work was to study the degradation and gelling ability of myofibrillar protein extracts obtained from beef treated with lactic acid of chemical and microbial origins, stored at 4 and 20C. The gelling ability was considerably reduced by lactic acid treatment as a result of protein denaturation in acid conditions at both storage temperatures. Scanning electron microscopy showed loose structures resulting in low penetration resistance and storage modulus. Treatments with lactic acid or lactic acid bacteria (LAB) had similar effect on tan,, affecting gel rigidity but not elasticity. Penetration in gels obtained from LAB-treated meat was highly correlated with myosin degradation. Lactobacillus carnis -treated meat produced compact gels with high penetration resistance and storage modulus, although the structure became looser with storage time. LAB treatment, although not as efficient as lactic acid as a meat preservative, is a milder process causing less severe changes in meat structure rheology. PRACTICAL APPLICATIONS The potential of lactic fermentation by selected strains is somewhat limited as compared to lactic acid preservation of meat substrates, regarding pH reduction and its consequence on pathogens and spoilage microorganism population reduction. However, lactic acid bacteria (LAB) treatments are milder; therefore, changes in protein structure and rheology are less severe. Lactic acid in its chemical form promotes protein changes, whereas LAB does not. As myofibrillar protein configuration is responsible for most meat functional properties, such as gel and emulsion formation, it is important that protein structure remains unchanged as much as possible. Using nonproteolytic strains, protein degradation can only be altered by endogenous or bacteria-produced enzymes, which can be inhibited by several means. Meat preservation by lactic fermentation with selected strains can be an alternative when keeping meat protein functional properties unaltered. [source]


    Forming Al2O3,Al Composites with Controlled Compositions by Reactive Metal Penetration of Dense Aluminosilicate Preforms

    JOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 5 2000
    William G. Fahrenholtz
    Alumina,Al composites with controlled compositions containing 17 to 31 vol% Al were formed by reactive metal penetration (RMP) of molten Al into dense aluminosilicate preforms. A reaction model has been developed to accurately predict composite Al content from the SiO2:Al2O3 ratio of the preform. The model was tested and validated by comparing predicted composite compositions to those measured for RMP composites made from preforms of known compositions. Aluminosilicate preforms containing 28.1, 39.0, and 54.1 wt% SiO2 were reacted with Al to produce composites with 17, 25, and 31 vol% Al, respectively. These values compare favorably to Al contents of 17.7, 22.7, and 28.6 vol% Al predicted using the reaction model. The differences between predicted and measured values are attributed to the presence of porosity and Si in the composites, as well as impurities in the SiO2 glass phase and porosity in the preforms, none of which is specifically accounted for in the reaction model. [source]


    Pharmacokinetics of 4-aminopyridine derivatives in dogs

    JOURNAL OF VETERINARY PHARMACOLOGY & THERAPEUTICS, Issue 5 2009
    N. J. OLBY
    Blockade of potassium channels with 4-aminopryidine (4-AP) restores conduction to demyelinated axons and improves function. Unfortunately, 4-AP causes adverse effects and its clinical effects are unpredictable and limited. Derivatives of 4-AP have been tested in models of spinal cord injury in guinea pigs; three derivatives (methyl-, ethyl- and t -butyl carbamate derivatives) showed promise. This study investigates the safety and pharmacokinetics of these derivatives in dogs. Each derivative was administered orally to dogs starting at doses below effective doses in guinea pigs, and increasing the dose on sequential days. Routine blood work was performed prior to and 24 h after drug administration, blood samples were collected at intervals over 24 h after drug administration, and dogs were monitored for side effects. Derivative plasma levels were determined using high-pressure liquid chromatography. Cerebrospinal fluid (CSF) samples were taken to determine CSF levels. No adverse effects were seen even when using doses higher than those that improved conduction in spinal cord injured guinea pigs. Peak plasma levels occurred at 36.6 (ethyl), 87 (t -butyl) and 175 (methyl) min and plasma level was related to drug dose. Penetration of the central nervous system (CNS) was good, with CSF levels higher than plasma levels for the t -butyl derivative. [source]


    Penetration of ceftiofur into sterile vs.

    JOURNAL OF VETERINARY PHARMACOLOGY & THERAPEUTICS, Issue 3 2005
    Mannheimia haemolytica -infected tissue chambers in beef calves after subcutaneous administration of ceftiofur crystalline free acid sterile suspension in the ear pinna
    The effect of Mannheimia haemolytica infection on the penetration of ceftiofur and desfuroylceftiofur metabolites into tissue chambers was studied in cattle after subcutaneous administration of ceftiofur crystalline free acid sterile suspension (CCFA-SS). Four tissue chambers were implanted subcutaneously in each of 12 calves. Approximately 45 days after implantation, two chambers were inoculated with M. haemolytica (106 colony-forming units per chamber) while the remaining two chambers were inoculated with sterile phosphate-buffered saline. Twenty-four hours after inoculation, CCFA-SS was administered subcutaneously in the middle third of the caudal ear pinna of each calf. Chamber fluid and blood samples were collected at predetermined times for 10 days following dosing and analyzed for ceftiofur and desfuroylceftiofur metabolites by high-performance liquid chromatography. Concentrations of ceftiofur and desfuroylceftiofur metabolites in plasma and tissue chamber fluid remained above a threshold of 0.2 ,g/mL for at least 8 days. Infected tissue chamber fluid concentrations of ceftiofur and desfuroylceftiofur metabolites were significantly higher than those in non-infected tissue chamber fluid, which correlated with significantly higher total protein concentration in infected tissue chambers. These results indicate that single subcutaneous administration of CCFA-SS at 6.6 mg/kg can be expected to provide effective therapy of susceptible bacterial infections for a period of at least 1 week. [source]


    Nd:YAG laser interaction with mine wrapping materials

    LASER PHYSICS LETTERS, Issue 2 2004
    T. Rothacher
    Abstract According to UN publications landmines are a daily threat in approximately 70 countries of the world. There exist different ways to destroy detected antipersonnel mines. Neutralisation of mines with laser is a possibility that offers several advantages like working from safe distance and possibly mine destruction by deflagration and without explosion. Previous work has shown the importance of an absorbing mine wrapping material to achieve the desired burning process. In this paper, interaction of Nd:YAG laser radiation with different realistic synthetic mine wrapping materials is investigated. Penetration duration of laser radiation at , = 1.064 ,m through samples with different thickness is measured. Penetration through all tested materials is achieved at an incident power of 28.8 W. With an investigated material thickness up to 3 mm, penetration duration is in the range of seconds. Also penetration through a real mine case consisting of bakelite is achieved. (© 2004 by HMS Consultants. Inc. Published exclusively by WILEY-VCH Verlag GmbH & Co.KGaA) [source]


    QSAR Models for the Dermal Penetration of Polycyclic Aromatic Hydrocarbons Based on Gene Expression Programming

    MOLECULAR INFORMATICS, Issue 7 2008
    Tao Wang
    Abstract Gene Expression Programming (GEP) is a novel machine learning technique. The GEP is used to build nonlinear quantitative structure activity relationship model for the prediction of the Percent of Applied Dose Dermally Absorbed (PADA) over 24,h for polycyclic aromatic hydrocarbons. This model is based on descriptors which are calculated from the molecular structure. Three descriptors are selected from the descriptors pool by Heuristic Method (HM) to build a multivariable linear model. The GEP method produced a nonlinear quantitative model with a correlation coefficient and a mean error of 0.92 and 4.70 for the training set, 0.91 and 7.65 for the test set, respectively. It is shown that the GEP predicted results are in good agreement with experimental ones. [source]


    Determining Contact Angles of Powders by Liquid Penetration

    PARTICLE & PARTICLE SYSTEMS CHARACTERIZATION, Issue 4 2004
    Ulrich Teipel
    Abstract The wettability of a powder is important, especially in chemical and pharmaceutical technologies when considering the manufacturing process and the properties of the final product. However, contact angle methods for powders are problematic. The common measurement techniques are the sessile drop method and the liquid penetration method. In this work the determination of contact angles of powders by liquid penetration is considered. In particular, we investigated the influence of the sample preparation and sampling device on the wetting process. A bulk with constant properties during the measurement must be guaranteed. We postulate a packing procedure to obtain reproducible measurements by ensuring constant powder properties. [source]


    Post-infection development and histopathology of Meloidogyne arenaria race 1 on Arachis spp.

    PLANT PATHOLOGY, Issue 5 2008
    K. Proite
    The reproductive behaviour of the root-knot nematode Meloidogyne arenaria race 1 was compared on two wild species of Arachis (A. duranensis and A. stenosperma) and cultivated peanut (A. hypogaea cv. IAC-Tatu-ST). The three species were considered moderately susceptible, resistant, and susceptible, respectively. Penetration and development of the root-knot nematode in the resistant species was reduced in comparison with that occurring in susceptible plants. Several cell features, including dark blue cytoplasm and altered organelle structure were observed in the central cylinder of A. stenosperma, indicating a hypersensitive-like response (HR) of infested host cells. Neither giant cells, nor nematodes developed beyond the second stage, were found on A. stenosperma. Arachis duranensis showed a delay in the development of nematodes in the roots compared to A. hypogaea. The two wild peanut species were chosen to be the contrasting parents of a segregating population for mapping and further investigation of resistance genes. [source]


    Infection of onion leaves by Alternaria porri and Stemphylium vesicarium and disease development in controlled environments

    PLANT PATHOLOGY, Issue 3 2000
    H. Suheri
    Infection of onion by Alternaria porri and Stemphylium vesicarium was investigated under a range of controlled temperatures (4,25°C) and leaf wetness periods (0,24 h). Conidia of A. porri and S. vesicarium germinated within 2 h when incubated at 4°C. Terminal and intercalary appressoria were produced at similar frequencies at or above 10°C. The maximum number of appressoria was produced after 24 h at 25°C. Penetration of leaves by both pathogens was via the epidermis and stomata, but the frequency of stomatal penetration exceeded that of epidermal penetration. There was a strong correlation (R2 > 90%) between appressorium formation and total penetrations at all temperatures. Infection of onion leaves occurred after 16 h of leaf wetness at 15°C and 8 h of leaf wetness at 10,25°C, and infection increased with increasing leaf wetness duration to 24 h at all temperatures. Interruption of a single or double leaf wetness period by a dry period of 4,24 h had little effect on lesion numbers. Conidia of A. porri and S. vesicarium separately or in mixtures caused similar numbers of lesions. Alternaria porri and S. vesicarium are both potentially important pathogens in winter-grown Allium crops and purple leaf blotch symptoms were considered to be a complex caused by both pathogens. [source]


    Experimental study of sharp-tipped projectile perforation of GFRP plates containing sand filler under high velocity impact and quasi-static loadings

    POLYMER COMPOSITES, Issue 10 2009
    Ali Reza Sabet
    Penetration and perforation behavior of glass fiber reinforced plastic (GFRP) plates containing 20% sand filler have been investigated via high velocity impact tests using sharp tipped (30°) projectile and quasi-static perforation tests. Two size sand filler (75 and 600 ,m) were used in 4-, 8-, and 14-layered laminated composite plates to study sensitivity of filler size toward loading system. Composite plates were examined for perforation load rate at 5 mm/min and high-velocity impact loading up to 220 m/s. Results indicated higher energy absorption for GFRP plates containing sand filler for both high-velocity impact and quasi-static perforation tests. Higher ballistic limits were recorded for specimens containing sand filler. The study showed clear role played by coarse-sized sand filler as a secondary reinforcement in terms of higher energy absorption as compared with nonfilled and specimens containing fine-sized fillers. The investigation successfully characterized behavior of quasi-static test during penetration and perforation of the sharp-tipped indenter as an aid for impact application studies. Residual frictional load in the specimens containing sand filler constituted considerable portion of load bearing during perforation in quasi-static tests. Delaminations followed by fiber and matrix fracture were major failure mode in high-velocity tests and the main energy absorbing mechanism in thick-walled plates, whereas in quasi-static tests the failures were more of matrix fracture and fiber sliding. POLYM. COMPOS., 2009. © 2008 Society of Plastics Engineers [source]


    Prognostic Value of Various Spermatological Attributes as Predictors of Zona Binding and Zona Penetration of Buffalo (Bubalus bubalis) Semen

    REPRODUCTION IN DOMESTIC ANIMALS, Issue 1 2009
    S Selvaraju
    Contents Twenty-four ejaculates from six (four ejaculates each) Surti buffalo bulls aged 4,8 years were used to assess various attributes of spermatozoa influencing the zona-binding and zona-penetration tests. Ejaculates from each bulls were subjected to in vitro sperm--zona binding and sperm--zona penetration tests (four replicates per bull) using immature buffalo oocytes. The average number of spermatozoa bound per oocyte was 27.79 ± 5.90. The average number of spermatozoa penetrated per oocyte was 3.35 ± 0.64. The average number of zona-bound and -penetrated spermatozoa differed significantly between animals. Significant difference (p < 0.05) was observed between the plasmalemma integrity as assessed by eosin--nigrosin stain and hypo-osmotic swelling (HOS) test. Furthermore, the percentage of cells positive for the HOS test, i.e. functional membrane integrity (51.25 ± 2.32) was significantly (p < 0.05) higher than hypo-osmotic swelling-Giemsa (HOS-G) test, i.e. the subpopulation of spermatozoa positive for functional membrane and acrosomal integrities (42.87 ± 4.56). The HOS test had significant correlations with plasmalemma integrity as measured by the vital stain, eosin--nigrosin (r = 0.85, p < 0.05). The HOS-G test also had significant correlation with plasmalemma integrity measured by vital stains such as eosin--nigrosin (r = 0.90, p < 0.05) and fluorogenic stains [carboxyfluorescein diacetate (CFDA) and propidium iodide (PI); r = 0.92, p < 0.01] and HOS test (r = 0.93), acrosomal integrity (r = 0.86, p < 0.05) and mitochondrial membrane potential (r = 0.99, p < 0.01). The plasmalemma integrity (fluorogenic stain), functional membrane integrity (HOS test), subpopulation of spermatozoa positive for functional membrane and acrosomal integrities (HOS-G test) and mitochondrial membrane potential had significant (p < 0.05) correlation with sperm zona binding and penetration. The present study indicates that these parameters could represent important determinants of sperm quality influencing zona binding and penetration. [source]


    Penetration of Shear Flow Into an Array of Rods Aligned With the Flow

    THE CANADIAN JOURNAL OF CHEMICAL ENGINEERING, Issue 6 2004
    Anthony M. J. Davis
    Abstract Shear flow over a square array of widely-spaced rods aligned with the flow is investigated using singularity methods to solve Stokes equation. The flow field is determined for various arrays occupying a fraction of a Couette channel, for solid volume fractions from 0.001 to 0.1. Flow penetration into an array is quantified by the slip velocity at the array edge. This velocity is much greater than when the flow is across the array but still less than the value predicted by the use of Brinkman's equation. À l'aide de méthodes de singularité destinées à résoudre l'équation de Stokes, on a étudié l'écoulement de cisaillement sur un vaste arrangement carré de tiges largement espacées alignées à l'écoulement. Le champ d'écoulement est déterminé pour divers arrangements occupant partiellement un canal de Couette, pour des fractions volumiques de solides comprises entre 0,001 et 0,1. La pénétration de l'écoulement dans le dispositif est quantifiée par la « vitesse de glissement au bord du dispositif. Cette vitesse est beaucoup plus grande que dans le cas où l'écoulement est transversal par rapport au dispositif mais est encore inférieure à la valeur prédite au moyen de l'équation de Brinkman. [source]


    The effect of desflurane on filtration performance of breathing system filters,

    ANAESTHESIA, Issue 8 2010
    Y. Poonawala
    Summary This study assessed the effect of desflurane on the filtration performance of six breathing system filters intended for use with adults. Three filters contained an electrostatic filter material and three contained a pleated glass fibre filter material. Five samples of each model of filter were exposed to 6% v/v of desflurane for 1 h, 12% v/v of desflurane for 1 h, 12% v/v of desflurane for 4 h and air only for 1 h. Five samples of each filter were also tested without exposure to any vapour or air. The filtration performance was measured by challenging each filter with an aerosol of sodium chloride particles using a Moore's test rig. Penetration of particles through the electrostatic filters increased following exposure to a higher concentration of desflurane for a longer duration (p < 0.001). The effect on two of the pleated filters was not significant (p = 0.55 and p = 0.64). The effect on the remaining pleated filter was significant (p < 0.001) but small. The efficiency of some filters decreases when they are exposed to high concentrations of desflurane for a long duration. This effect appears more marked in electrostatic filters compared with pleated filters. [source]


    Microleakage of composite resin restorations in cervical cavities prepared by Er,Cr:YSGG laser radiation

    AUSTRALIAN DENTAL JOURNAL, Issue 2 2008
    S Shahabi
    Abstract Background:, Evaluation of microleakage is important for assessing the success of new methods for surface preparation and new adhesive restorative materials. The aim of this laboratory study was to assess microleakage at the margins of composite restorations in Er,Cr:YSGG laser prepared cavities on the cervical aspects of teeth by means of dye penetration, and compare this with conventionally prepared and conditioned cavities. Methods:, Class V cavities were produced on sound extracted human teeth, which had been assigned randomly to one of three groups (N = 10 each), as follows: Group 1 , prepared using a diamond cylindrical bur and then treated with 37% phosphoric acid; Group 2 , irradiated with an Er,Cr:YSGG laser (Biolase Waterlase) and then treated with 37% phosphoric acid; Group 3 , irradiated only with the laser. After application of bonding agent (Excite, Ivoclar Vivadent), all cavities were restored with composite resin (Heliomolar). After polishing the restorations, the teeth were thermocycled from 5,50°C for 500 cycles. Dye leakage was assessed after immersion in methylene blue, by examining longitudinal sections in a stereomicroscope at ×30 magnification. Results:, The extent of dye penetration was lowest in the laser only group (Group 3). Penetration of dye to dentine and axial walls occurred in 80 per cent of conventionally prepared (bur + acid) specimens, but in the laser group, dye penetration to the axial wall occurred in only 30 per cent of cases. There was a strong statistical association between treatment group and the distribution of microleakage scores (Chi-square, P = 0.0023). Conclusions:, For Class V cavities, with the adhesive materials employed, higher microleakage occurs with phosphoric acid etching of bur- or laser-cut surfaces, than with the surface created by use of the laser alone without additional conditioning. [source]


    Peroxide Penetration Into The Pulp From Whitening Strips

    AUSTRALIAN ENDODONTIC JOURNAL, Issue 1 2005
    Article first published online: 11 FEB 2010
    No abstract is available for this article. [source]


    Bacterial Cell Penetration by ,3 -Oligohomoarginines: Indications for Passive Transfer through the Lipid Bilayer

    CHEMBIOCHEM, Issue 6 2005
    Birgit Geueke Dr.
    Uptake of fluorescently labeled ,-oligohomoarginines amides by bacteria was examined with confocal laser scanning microscopy and fluorescence quenching assays. The results indicate that microorganisms, which have no endocytotic mechanisms for transmembrane transport, internalize the peptides through an unidentified alternative pathway (see micrograph). [source]


    Penetration of Porous Systems by Nonwetting Liquids

    CHEMICAL ENGINEERING & TECHNOLOGY (CET), Issue 9 2003
    S. Palzer
    Wetting of porous systems and the corresponding penetration of liquids into single capillaries is one of the most important processes in process engineering. Wetting liquids with a contact angle smaller than 90° are penetrating spontaneously into capillaries. The presented study demonstrates that, under certain conditions, even nonwetting liquids with contact angles larger than 90° can do so. Furthermore, it is shown that the time for such wetting processes can be calculated. [source]


    Addressing Central Nervous System (CNS) Penetration in Drug Discovery: Basics and Implications of the Evolving New Concept

    CHEMISTRY & BIODIVERSITY, Issue 11 2009
    Andreas Reichel
    Abstract Despite enormous efforts, achieving a safe and efficacious concentration profile in the brain remains one of the big challenges in central nervous system (CNS) drug discovery and development. Although there are multiple reasons, many failures are due to underestimating the complexity of the brain, also in terms of pharmacokinetics (PK). To this day, PK support of CNS drug discovery heavily relies on improving the blood,brain barrier (BBB) permeability in vitro and/or the brain/plasma ratio (Kp) in vivo, even though neither parameter can be reliably linked to pharmacodynamic (PD) and efficacy readouts. While increasing BBB permeability may shorten the onset of drug action, an increase in the total amount in brain may not necessarily increase the relevant drug concentration at the pharmacological target. Since the traditional Kp ratio is based on a crude homogenization of brain tissue, it ignores the compartmentalization of the brain and an increase favors non-specific binding to brain lipids rather than free drug levels. To better link exposure/PK to efficacy/PD and to delineate key parameters, an integrated approach to CNS drug discovery is emerging which distinguishes total from unbound brain concentrations. As the complex nature of the brain requires different compartments to be considered when trying to understand and improve new compounds, several complementary parameters need to be measured in vitro and in vivo, and integrated into a coherent model of brain penetration and distribution. The new paradigm thus concentrates on finding drug candidates with the right balance between free fraction in plasma and brain, and between rate and extent of CNS penetration. Integrating this data into a coherent model of CNS distribution which can be linked to efficacy will allow it to design compounds with an optimal mix in physicochemical, pharmacologic, and pharmacokinetic properties, ultimately mitigating the risk for failures in the clinic. [source]


    China's Penetration of the Korean Market: Stylized Facts and Welfare Effect

    CHINA AND WORLD ECONOMY, Issue 5 2010
    Kichun Kang
    F10; F14 Abstract China's penetration of the world market has been impressive. This paper uses highly disaggregated Korean import data (from 1992 to 2008) to examine China's penetration of the Korean market in the context of the composition of value (the extensive and intensive margins) and the product type (homogeneous and differentiated) in trade. The increase in Chinese imports has been attributed to the rapid increase in the import of new products (the extensive margin) and of existing products (the intensive margin). However, the growth rate of new products decelerated in the 2000s. The growth in the intensive margin was due to quantity, not price. Chinese imports to Korea did not improve over the period in terms of quality. Although Chinese products became cheaper, they were more differentiated over time. Welfare gains were realized through the expanded introduction of new products from China. However, much of the gains from Korea's Chinese product import boom were realized in earlier years (1992,2000) because even though imported products became more differentiated, the increase in the extensive margin was lower in more recent years (2001,2008). [source]