Penetration Patterns Research Articles

Spectral attenuation of solar radiation in Patagonian fjord and coastal waters and implications for algal photobiology

The spectral attenuation of solar irradiation was measured during summer in two types of coastal waters in southern Chile, a north Patagonian fjord (Seno Reloncaví) and open coast (Valdivia). In order to relate the light availability with the light requirements of upper subtidal seaweeds, the saturating irradiance for photosynthesis ( E k) from P– I curves was measured. In addition the UV risk was assessed. Based on the z 1% of PAR, the lower limit of the euphotic zone in the studied systems averaged 21 m ( K d 0.24 m −1) in Seno Reloncaví and 18 m ( K d 0.27 m −1) in the coast of Valdivia. Photosynthesis of the studied seaweeds was saturated at markedly lower irradiances than found in their natural depths at the time of the study. Solar radiation penetrating into these depths at both locations largely supports the light requirements for the photosynthesis of subtidal species: 50–160 μmol m −2 s −1 for seaweeds from Seno Reloncaví (7 m tidal range) and 20–115 μmol m −2 s −1 for Valdivia assemblages (2 m tidal range). Optimal light conditions to saturate photosynthesis ( E k) were present at 10–16 m water depth. The attenuation of solar irradiation did not vary significantly between the fjord and coastal sites of this study. However, the underwater light climates to which seaweeds are exposed in these sites vary significantly because of the stronger influence of tidal range affecting the fjord system as compared with the open coastal site. The patterns of UV-B penetration in these water bodies suggest that seaweeds living in upper littoral zones such as the intertidal and shallow subtidal (<3 m) may be at risk.

Antiretroviral drug concentrations in the male and female genital tract: implications for the sexual transmission of HIV

To summarize the recent literature (2008-2010) on antiretroviral (ARV) drug disposition into the male and female genital tract. Recent studies have confirmed that penetration of antiretroviral agents into the male and female genital tracts are both drug and sex specific. Concentrations achieved vary considerably depending on the class of drug studied, the sampling techniques used and the times samples are obtained. There appear to be several patterns of drug penetration into the male and female genital tract. In addition there appear to be different patterns of genital shedding under the influence of antiretroviral therapy. What effect these factors will have on the sexual transmission of HIV or the evolution and transmission of resistant HIV remains to be seen.

Computing gas/melt free interface of gas-assisted injection molding

A solution was put forward to predicate the flow pattern of gas penetration in gas-assisted injection molding. The differential equations that governed the flow field and gas/melt free-interface evolution were analyzed and discretized by Galerkin finite element method, and the free interface was located by the volume of fluid method. The gas was assumed as a fluid phase of constant density and viscosity instead of being simply treated as boundary conditions. The non-Newtonian property of polymer melt was characterized by Carreau model with four parameters. As a case study, different kinds of gas channel were modeled. The gas/melt free interface was captured. The gas front velocity and the pressure of gas/melt front were also computed. The edge shape of gas channel was discussed, which are helpful for the design of gas-assisted injection molding.

Structural study of carboxylesterase from hyperthermophilic bacteria Geobacillus stearothermophilus by molecular dynamics simulation

Carboxylesterases are ubiquitous enzymes with important physiological, industrial and medical applications such as synthesis and hydrolysis of stereo specific compounds, including the metabolic processing of drugs, and antimicrobial agents. Here, we have performed molecular dynamics simulations of carboxylesterase from hyperthermophilic bacterium Geobacillus stearothermophilus (GsEst) for 10 ns each at five different temperatures namely at 300 K, 343 K, 373 K, 473 K and 500 K. Profiles of root mean square fluctuation (RMSF) identify thermostable and thermosensitive regions of GsEst. Unfolding of GsEst initiates at the thermosensitive α-helices and proceeds to the thermostable β-sheets. Five ion-pairs have been identified as critical ion-pairs for thermostability and are maintained stably throughout the higher temperature simulations. A detailed investigation of the active site residues of this enzyme suggests that the geometry of this site is well preserved up to 373 K. Furthermore, the hydrogen bonds between Asp188 and His218 of the active site are stably maintained at higher temperatures imparting stability of this site. Radial distribution functions (RDFs) show similar pattern of solvent ordering and water penetration around active site residues up to 373 K. Principal component analysis suggests that the motion of the entire protein as well as the active site is similar at 300 K, 343 K and 373 K. Our study may help to identify the factors responsible for thermostability of GsEst that may endeavor to design enzymes with enhanced thermostability.

Clinical study of peroneal artery perforators with computed tomographic angiography: implications for fibular flap harvest

Previous studies of cutaneous perforators of the peroneal artery have shown great variability, and attest to the significant anatomical variability in this region. Furthermore, the vascular anatomy of the region has been considered unreliable in the prediction of ideal perforator topography. Preoperative imaging has been suggested as a means for improving preoperative awareness, with Doppler ultrasound and eco-colour (duplex) ultrasound as useful tools. Multi-detector row computed tomographic angiography (CTA or angio CT), has emerged as a significant improvement, providing non-invasive operator-independent details of the vascular anatomy. We utilised this tool to perform an in vivo, anatomical study of the peroneal artery perforators, and demonstrating the usefulness of CTA in planning the osteocutaneous free fibula flap. Forty-one consecutive patients (82 limbs) underwent CTA of the lower limb vasculature, with the anatomical details of the peroneal artery cutaneous perforators assessed. CTA was able to demonstrate the size, course and penetration pattern of all perforators over 0.3 mm in diameter, with measurements for perforators over 0.8 mm diameter recorded for analysis. Of 171 such perforators, accurate identification of the size (mean diameter 1.91 mm), course (59.6% septocutaneous, 29.2% musculocutaneous and 11.1% septomusculocutaneous) and location was achieved. The vascular anatomy of peroneal artery perforators is highly variable, and thus there is a role for preoperative imaging. CTA can demonstrate cases where there is aberrant or non-preferred anatomy, or select the limb of choice for harvest.

Factors influencing infection of eucalypts by Cylindrocladium pteridis

The pattern of Cylindrocladium pteridis adhesion, germination and penetration in eucalypt leaves was assessed using scanning electron microscopy. The effects of inoculum concentration, leaf wetness period, plant age and branch position of cylindrocladium leaf blight and defoliation severity were assessed in greenhouse studies using two Eucalyptus grandis × E. urophylla hybrid clones. Penetration occurred through stomata, and there was no difference in the number of penetrations between young and old leaves. Percentage leaf area with lesions and defoliation increased with the increase in inoculum concentration (1 × 102 to 105 conidia mL−1), duration of leaf wetness period (6 to 48 h) and plant age (60 to 180 days). Branch position in plants also significantly affected the percentage leaf area with lesions and defoliation, the latter variable being significantly higher at the stem base. The highest values of lesion area were also observed on leaves at the stem base in both clones. The Pearson correlation between defoliation and leaf area with lesions was significant in all experiments (r &gt; 0·9) indicating a high association between these two variables.

Angiogenesis and CD34 Expression as a Predictor of Recurrence in Oral Squamous Cell Carcinoma

To assess immunohistologic features of angiogenesis of T1N0M0 oral squamous cell carcinoma (OSCC), and to identify predictors of regional recurrence. The identification of prognostic markers of early lymph node involvement in OSCC could allow for the use of more targeted biologic therapies for patients with early-stage tumors. The study included patients treated for T1N0M0 OSCC at the Mayo Clinic from 1986 to 2001. All patients had initial surgical resection without neck dissection, and all had adequate follow-up with histologic specimens for review. Patients with lip, pharyngeal, or salivary gland tumors were excluded. Patient specimens were regraded and assessed for the histologic markers p53 and CD34 (penetrating and circumscribing patterns). The Kaplan-Meier method was used to estimate patient survival and survival free of regional recurrence. The study included 175 patients. The overall 5-year survival was 75%, and 5-year survival free of regional recurrence was 80.3%. Twenty-eight patients had regional recurrence. High-grade tumors (P = .03) and the penetrating pattern of CD34 (P = .02) were significantly associated with early regional metastasis from early-stage OSCC. The presence of p53 was not independently associated as a marker for regional metastasis. Early-stage T1 OSCC with high-grade lesions and a penetrating pattern of CD34 was associated with a statistically significant risk of cervical lymph node metastasis, compared with a circumscribing pattern of CD34.

Investigation of Water and Methanol Sorption in Monovalent- and Multivalent-Ion-Exchanged Nafion Membranes Using Electron Spin Resonance

Electron spin resonance (ESR) spectroscopy was used to monitor the local environment of 2,2,6,6-tetramethyl-4-piperidone N-oxide (TEMPONE) spin probe in Li(+), Ca(2+), and Al(3+) ion-exchanged Nafion 117 membranes swollen with mixed methanol/water solvent at varying compositions. The (14)N hyperfine splitting, a(N), which reflects the local polarity of the nitroxide probe, remains nearly steady at higher solvent contents but increases substantially at lower solvent contents, reflecting close contact with the ions. The rotational rate (R) of the probe increased with solvent content, depending strongly on the amount of solvent at low contents but increasing more gradually at higher solvent contents, similar to the behavior of previously measured solvent translation diffusion coefficients. The rotational rate data from water-containing membranes were fitted using the Fujita free-volume diffusion model, which indicated that multivalent ions tend to increase the free volume fraction of the polymer while decreasing that of the solvent phase. Methanol-containing membranes exhibited greater variation with different exchange ions, but the data could not be fit using the free-volume model, suggesting that the assumption of two phases underlying the free-volume model might not apply to this case. The difference in the trends of swelling between water and methanol is consistent with previous results that have indicated different patterns of penetration for the two solvents. The results are interpreted in terms of changes in membrane morphology with higher-valence ions.

Bond strength of self-etch adhesives to pre-etched enamel

Objective Bond strengths of composite resin to enamel using four self-etch adhesive (SEA) systems were compared with the bond strength of an etch-and-rinse adhesive (ERA) system, for both polished enamel and enamel pre-etched with phosphoric acid. The objective was to determine if the pre-etching would increase the bond strengths of the SEA systems to match the ERA system. Methods Ten specimens were used for each adhesive to determine 24-h resin composite to enamel shear bond strengths (SBS) to polished (4000 grit) human enamel and this was repeated for the SEA systems for enamel that was pre-etched with phosphoric acid for 15 s. SEM analysis was made to assess the degree of etching and resin penetration into enamel for each of the adhesive systems. Data were analyzed by a two factor ANOVA with a Tukey HSD post hoc test. Results The SBS to polished enamel for all four SEA systems were statistically significantly lower ( p < 0.05) than the ERA control, but with pre-etched enamel there were no statistically significant differences ( p > 0.05) between any of the adhesive systems. All four of the SEA systems demonstrated statistically significant increases in bond strength between bonding to polished and pre-etched enamel, ranging from 27% to 86%. The results of SEM analysis showed no differences in the resin penetration patterns of any of the adhesives for enamel that was etched with phosphoric acid. Significance Pre-etching enamel may enhance the bond strength of SEA systems to values comparable with those found with ERA adhesive systems, which may improve their overall performance in clinical use.

Ponded infiltration into soil with biopores — field experiment and modeling

AbstractPreferential movement of water in macropores plays an important role when the process of ponded infiltration in natural porous systems is studied. For example, the detailed knowledge of water flow through macropores is of a major importance when predicting runoff responses to rainfall events. The main objectives of this study are to detect preferential movement of water in Chernozem soil and to employ numerical modeling to describe the variably saturated flow during a field ponded infiltration experiment. The infiltration experiment was performed at the Macov experimental station (Calcari-Haplic Chernozem in Danubian Lowland, Slovakia). The experiment involved single ring ponded infiltration. At the quasi steady state phase of the experiment dye tracer was added to the infiltrating water. Then the soil profile was excavated and the penetration pattern of the applied tracer was recorded. The abundance of biopores as a product of fauna and flora was found. To quantify the preferential flow effects during the infiltration experiment, three-dimensional axisymmetric simulations were carried out by a two-dimensional dual-continuum numerical model. The water flow simulations based on measured hydraulic characteristics without consideration of preferential flow effects failed to describe the infiltration experiment adequately. The 3D axisymmetric simulation based on dual-permeability approach provided relatively realistic space-time distribution of soil water pressure below the infiltration ring.

Effect of urea and detergents on the ability of human spermatozoa to penetrate zona-free hamster oocytes.

Washing of human spermatozoa with either BWW alone or with the same buffer containing 0.1 M urea, 0.005% SDS or 0.001% NP40 affected the penetration ability of the gametes into zona-free hamster oocytes to various degrees. In contrast, human spermatozoa washed with BWW buffer containing 0.3 M urea had an increased ability to fuse with the heterologous oocytes when compared to controls capacitated with BWW/BSA. Moreover, the presence or absence of BSA in the insemination medium did not further modify this enhanced penetration pattern. The BWW, BWW/0.1 M urea and BWW/SDS treatments apparently mimicked some of the in vitro capacitation properties of albumin-containing media; the BWW/0.3 M urea treatment overpowered the capacitation and acrosomal reaction extent obtained with BWW+BSA. In all samples the motility of the spermatozoa washed with BWW buffer alone or containing various additives (but no albumin) was significantly decreased if compared to the motility of semen samples washed with albumin containing media. However, each sperm sample behaved differently when exposed to a given buffer.

Hemorragia digestiva alta, secundaria a un tumor estromal yeyunal, en un paciente con neurofibromatosis tipo 1

Neurofibromatosis type 1 (NF1) is a multisystemic disease with an autosomal dominant pattern of inheritance, complete penetrance and variable expressivity. This disease affects one in every 3,000 individuals and one out of every 200 patients with mental retardation. Gastrointestinal bleeding secondary to gastrointestinal mesenchymal tumors is one of the many complications associated with NF1. We report the case of a patient with NF1 admitted to hospital for severe gastrointestinal hemorrhage secondary to a jejunal gastrointestinal stromal tumor (GIST) with favorable outcome after surgical removal.

Evaluation of electrospun fibrous scaffolds of poly( dl-lactide) and poly(ethylene glycol) for skin tissue engineering

This study is derived from the innate concerns of electrospun poly( DL-lactide) (PDLLA) fibers as tissue engineering scaffolds: hydrophobic surface, surface erosion and dimensional shrinkage, which are not favorable to trigger the initial adhesion and further growth and population of cells. Blending electrospinning of PDLLA and poly(ethylene glycol) (PEG) with different PEG contents was evaluated for optimal tissue engineering scaffolds. The surface hydrophilicity was improved, and the degradation patterns of PDLLA/PEG mats changed from surface erosion to bulk degradation with the increase in PEG contents. The dimensional shrinkage was alleviated through the formation of crystal regions of PEG in the fiber matrix. The PDLLA/PEG fibrous mats were slightly weakened with the increase in the PEG contents, but a significant decrease in the tensile strength could be found for those with PEG contents of over 40%. Human dermal fibroblasts (HDFs) interacted and integrated well with the surrounding fibers containing 20 and 30% PEG, which provided significantly better environment for biological activities of HDFs than electrospun PDLLA mats. It indicated that electrospun mats containing 30% PEG exhibited the most balanced properties, including moderately hydrophilic surface, minimal dimensional changes, adaptable bulk biodegradation pattern and enhancement of cell penetration and growth within fibrous mats.

Uncovering Social Network Structures through Penetration Data

We show how networks modify the diffusion curve by affecting its symmetry. We demonstrate that a network's degree distribution has significant impact on the contagion properties of the subsequent adoption process, and propose a method for uncovering the degree distribution of the adopter network underlying the dissemination process, based exclusively on limited early-stage penetration data. In this paper we propose and empirically validate a unified network-based growth model that links network structure and penetration patterns. Specifically, using external sources of information, we confirm that each network degree distribution identified by the model matches the actual social network that is underlying the dissemination process. We also show empirically that the same method can be used to forecast adoption using an estimation of the degree distribution and the diffusion parameters, at an early stage (15%) of the penetration process. We confirm that these forecasts are significantly superior to those of three benchmark models of diffusion. Our empirical analysis indicates that under heavily right-skewed degree distribution conditions (such as scale-free networks), the majority of adopters (in some cases, up to 75%) join the process after the sales peak. This strong asymmetry is a result of the unique interaction between the dissemination process and the degree distribution of its underlying network.

Yield determination in olive hedgerow orchards. I. Yield and profiles of yield components in north - south and east - west oriented hedgerows

A study of the vertical distribution of flowering and fruit set and of components of yield (fruit numbers, fruit size, and fruit oil content) was maintained for 2 years in N–S- and E–W-oriented olive hedgerows of comparable structure (row spacing 4 m, hedgerow height to 2.5 m, width c. 1 m) near Toledo, Spain (39.9°N). Mean yield of the N–S orchard was 1854 kg oil/ha without difference between sides or years. Yield of the E–W orchard was greater in 2006, producing 2290 kg/ha, but only 1840 kg/ha in 2007, the same as the N–S orchard. The S side of the E–W orchard yielded more (59%) than the N side in 2007. In both orchards and years, most fruit was produced at 1.0–2.0 m height and fruit density was the most influential component in these differences, reflecting more intense bud initiation in these upper layers. Other components that determined fruit number, fertile inflorescences, fruits per fertile inflorescence, and fruit drop were not significantly different between layers. Fruit characteristics depended on hedgerow position. In both N–S and E–W hedgerows, fruit high in the hedgerow was the largest, most mature, and with highest oil content. These differences were more marked in N–S than in E–W hedgerows. Fruit growth and development were concentrated from the middle of September until the end November. Oil content per fruit increased linearly during that period when 65% of final oil content was accumulated. Similar patterns were observed between sides. The results of yield and yield profiles are discussed in the general context of light interception. The results suggest the importance of hedgerow porosity, and distinct penetration patterns of direct-beam radiation through N–S and E–W hedgerows, as the basis for explanation of the high yield of the N side of E–W hedgerows.

A study on the fuel injection and atomization characteristics of soybean oil methyl ester (SME)

The spray atomization characteristics of an undiluted biodiesel fuel (soybean oil methyl ester, SME) in a diesel engine were investigated and compared with that of diesel fuel (ultra low sulfur diesel, ULSD). The experimental results were compared with numerical results predicted by the KIVA-3V code. The spray characteristics of the spray tip penetration, spray area, spray centroid and injection delay were analyzed using images obtained from a visualization system. The Sauter mean diameter (SMD) was analyzed using a droplet analyzer system to investigate the atomization characteristics. It was found that the peak injection rate increases and advances when the injection pressure increases due to the increase of the initial injection momentum. The injection rate of the SME, which has a higher density than diesel fuel, is higher than that of diesel fuel despite its low injection velocity. The high ambient pressure induces the shortening of spray tip penetration of the SME. Moreover, the predicted spray tip penetration pattern is similar to the pattern observed experimentally. The SMD of the SME decreases along the axial distance. The predicted local and overall SMD distribution patterns of diesel and SME fuels illustrate similar tendencies when compared with the experimental droplet size distribution patterns.

Cementing technique in femoral resurfacing

The cementing technique is one of the various speculated factors that might contribute to the failures of resurfacing arthroplasty of the hip. The influence of bony preparation by jet lavage or lavage only in combination with different cementing techniques and cements of different viscosity in a study on fresh human femoral heads has not been evaluated so far. Sixty fresh human femoral heads were prepared for resurfacing following manufacturers' instructions and divided into 12 groups. The different groups received either syringe lavage or jet lavage and either a low-, medium- or high-viscosity cement with either packing or quarter filling of the implant with recess of the femoral stem in each case. Application of the implant was standardized. After polymerization, the femoral heads were cut into quarters and polished. Cement penetration was assessed using a square millimeter grid under optical zoom. Manual packing with high viscosity cement is a reproducible method in resurfacing arthroplasty. Syringe lavage and jet lavage mainly showed comparable cement penetration patterns when applied same cementing techniques. The penetration depth ranged from a mean of 0.6 to 3.2 mm with 0.4 being the lowest and 4.0 being the deepest. The mantle thickness ranged from 0.8 to 2.4 mm with statistically significant thicker mantles with filling, compared to packing. Our results showed distinct less penetration depth than previously reported and that just medium viscosity cement reached reliable results in the supposed range of penetration depth and cement mantle thickness. Jet lavage should be recommended for the low-viscosity cement but avoided in combination with a cement filling technique of lower viscosity cements. Filling of the implant caused the greatest penetration depth and a higher number of incomplete seatings and should therefore be avoided.

Efficient Intraocular Penetration of Topical Anti–TNF-α Single-Chain Antibody (ESBA105) to Anterior and Posterior Segment without Penetration Enhancer

This study was designed to characterize ocular penetration pathways of ESBA105, a topically administered single-chain antibody (scFv) against tumor necrosis factor (TNF)-alpha, to the anterior and posterior segment of the eye. Fresh enucleated whole eyes and isolated corneas of rabbits mounted in perfusion chambers were used for ex vivo penetration studies. In vivo pharmacokinetics and ocular biodistribution of ESBA105 after intravitreal injection or topical administration as eye drops were investigated in rabbits. After topical administration as eye drops, without a penetration enhancer, ESBA105 reached therapeutic levels in the anterior and posterior segment of the eye. ESBA105 migrated to aqueous humor via corneal penetration and vitreous and retina via intrascleral penetration pathways. In vivo, ESBA105 had a significantly prolonged elimination half-life in the vitreous of 25 hours compared with its serum half-life of 7 hours after i.v. administration. Therefore, based on frequency of topical dosing, a buildup of ESBA105 to distinct steady state levels in the vitreous could be achieved. Topically administered ESBA105 quickly reaches therapeutic levels in the anterior and posterior segment without any need for a penetration enhancer. Drug penetration and ocular biodistribution patterns of ESBA105 applied as eye drops appear highly attractive for clinical use to treat TNF-alpha dependant diseases of the eye.

In vivo skin penetration of quantum dot nanoparticles in the murine model: the effect of UVR.

Ultraviolet radiation (UVR) has widespread effects on the biology and integrity of the skin barrier. Research on the mechanisms that drive these changes, as well as their effect on skin barrier function, has been ongoing since the 1980s. However, no studies have examined the impact of UVR on nanoparticle skin penetration. Nanoparticles (NP) are commonly used in sunscreens and other cosmetics, and since consumer use of sunscreen is often applied to sun damaged skin, the effect of UVR on NP skin penetration is a concern due to potential toxicity. In this study, we investigate NP skin penetration by employing an in vivo semiconductor quantum dot nanoparticle (QD) model system. This model system improves NP imaging capabilities and provides additional primary interest due to widespread and expanding use of QD in research applications and manufacturing. In our experiments, carboxylated QD were applied to the skin of SKH-1 mice in a glycerol vehicle with and without UVR exposure. The skin collection and penetration patterns were evaluated 8 and 24 h after QD application using tissue histology, confocal microscopy, and transmission electron microscopy (TEM) with EDAX analysis. Low levels of penetration were seen in both the non-UVR exposed mice and the UVR exposed mice. Qualitatively higher levels of penetration were observable in the UVR exposed mice. These results are the first for in vivo QD skin penetration, and provide important insight into the ability of QD to penetrate intact and UVR compromised skin barrier. Our findings raise concern that NP of similar size and surface chemistry, such as metal oxide NP found in sunscreens, may also penetrate UV damaged skin.

The creep and wear of highly cross-linked polyethylene

The creep and wear behaviour of highly cross-linked polyethylene and standard polyethylene liners were examined in a prospective, double-blind randomised, controlled trial using radiostereometric analysis. We randomised 54 patients to receive hip replacements with either highly cross-linked polyethylene or standard liners and determined the three-dimensional penetration of the liners over three years. After three years the mean total penetration was 0.35 mm (SD 0.14) for the highly cross-linked polyethylene group and 0.45 mm (SD 0.19) for the standard group. The difference was statistically significant (p = 0.0184). From the pattern of penetration it was possible to discriminate creep from wear. Most (95%) of the creep occurred within six months of implantation and nearly all within the first year. There was no difference in the mean degree of creep between the two types of polyethylene (highly cross-linked polyethylene 0.26 mm, SD 0.17; standard 0.27 mm, SD 0.2; p = 0.83). There was, however, a significant difference (p = 0.012) in the mean wear rate (highly cross-linked polyethylene 0.03 mm/yr, SD 0.06; standard 0.07 mm/yr, SD 0.05). Creep and wear occurred in significantly different directions (p = 0.01); creep was predominantly proximal whereas wear was anterior, proximal and medial. We conclude that penetration in the first six months is creep-dominated, but after one year virtually all penetration is due to wear. Highly cross-linked polyethylene has a 60% lower rate of wear than standard polyethylene and therefore will probably perform better in the long term.