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Diffusion of the analytes across the diffusion boundary layers and subsequently through the fiber coatings determines the extraction kinetics of solid-phase microextraction in aqueous matrices. Besides, the matrix effects can distort the behaviors of the analytes transferring across the diffusion boundary layers. However, these processes were always studied via certain simplification, which often left the mass transfer through the fiber coatings unconsidered and the matrix effects partially investigated. Herein, a comprehensive study on the mass transfer processes in direct immersion solid-phase microextraction was presented. Under different agitation speeds, it was determined that the mass transfer coefficients across the diffusion boundary layers were three to six orders larger than those through the fiber coatings. However, the mass transfer across the diffusion boundary layers was generally the major rate-limiting step. In addition, the shuttle effect and the barrier effect, which were responsible for accelerating and retarding the extraction kinetics, respectively, were found to be the dominant matrix effect alternately under different agitation speeds. This study comprehensively illustrated the major rate-limiting step and the dominant matrix effects through recording the mass transfer coefficients.

Studying fish behaviour at hydropower dams is needed to facilitate the design and improvement of fish passage solutions, but few studies have focused on Atlantic salmon kelts. Here, we used radio telemetry (n = 40, size range = 50–81 cm) and acoustic sonar to study kelt movements in the forebay as well as their dam passage survival and subsequent migration success past multiple dams. We also compare radio telemetry and acoustic sonar observations of fish behaviour and used acoustic sonar to measure the depth distribution of fish approaching the turbine intake zone. Passage success at the dam was 41%, and mortality was largely associated with turbine passage (62%). The two fish that passed via the spill gates survived and continued their downstream migration. At the dam, all but one radio-tagged kelt approached the intake zone shortly after arrival to the forebay, and sonar data showed that approaching fish were predominantly surface oriented (72%, 88% and 96% of the observations were less than 1, 2 and 3 m deep, respectively). Turbine passage rate from the intake zone was higher at night than at day, indicating that the lack of visual cues may reduce the barrier effect of the 70-mm conventional trash rack. Turbine passage rate also increased with increasing hydropower generation. The percentage of observed upstream movements away from the intake zone compared with the total number of observations was considerably greater in the radio telemetry data (41%) than in the sonar data (4%). Only one fish survived passage of all eight hydropower dams to reach the lake. This low-passage survival underscores the need for remedial measures to increase the survival of migrating kelts, and the fish's surface orientation as well as their rapid approach to the intake rack should be taken into account when designing such measures. Copyright © 2017 John Wiley & Sons, Ltd.

Roads have a pervasive multi-faceted influence on ecosystems, including pronounced impacts on wildlife movements. In recognition of the scale-transcending impacts of transportation infrastructure, ecologists have been encouraged to extend the study of barrier impacts from individual roads and animals to networks and populations. In this study, we adopt an analytical representation of road networks as mosaics of landscape tiles, separated by roads. We then adapt spatial capture-recapture analysis to estimate the propensity of wildlife to stay within the boundaries of the road network tiles (RNTs) that hold their activity centres. We fit the model to national non-invasive genetic monitoring data for brown bears (Ursus arctos) in Sweden and show that bears had up to 73% lower odds of using areas outside the network tile of their home range centre, even after accounting for the effect of natural barriers (major rivers) and the decrease in utilization with increasing distance from a bear’s activity centre. Our study highlights the pronounced landscape-level barrier effect on wildlife mobility and, in doing so, introduces a novel and flexible approach for quantifying contemporary fragmentation from the scale of RNTs and individual animals to transportation networks and populations. non-invasive genetic sampling, road network tile, island biogeography, road ecology, spatial capture-recapture, fragmentation, carnivores, transportation network

The self-employed are often reported to be healthier than wageworkers; however, the cause of this health difference is largely unknown. The longitudinal nature of the US Health and Retirement Study allows us to gauge the plausibility of two competing explanations for this difference: a contextual effect of self-employment on health (benefit effect), or a health-related selection of individuals into self-employment (barrier effect). Our main finding is that the selection of comparatively healthier individuals into self-employment accounts for the positive cross-sectional difference. The results rule out a positive contextual effect of self-employment on health, and we present tentative evidence that, if anything, engaging in self-employment is bad for one's health. Given the importance of the self-employed in the economy, these findings contribute to our understanding of the vitality of the labor force. Copyright © 2014 John Wiley & Sons, Ltd.

The viability of many species depends on functional connectivity of their populations through dispersal across broad landscapes. This is particularly the case for the endangered brown bear in north-western Spain, with a total population of about 200 individuals in two subpopulations that are separated by a wide gap with low permeability. Our goal in this paper is to use state-of-the-art connectivity modeling approaches to provide detailed and quantitative guidance for conservation planning efforts aimed at improving landscape permeability for brown bears in Spain, with a particular focus on alleviating the barrier effect of transportation infrastructure. We predicted a regional connectivity network for brown bear by combining a multiscale habitat suitability model with factorial least-cost path density analysis. We found that the current composition and configuration of the landscape considerably constrain brown bear movements, creating a narrow bottleneck that limits flow of individuals between the two subpopulations. We identified key locations along the predicted corridors where efforts to increase road and railway permeability should be prioritized. The results provide a foundation for the development of spatially optimal management strategies to enhance connectivity within and between the subpopulations and to mitigate the impact of potential barriers to movement.

Reindeer herdsmen and authorities in Scandinavia fear detrimental effects from wind-power plants (WPs) on movements and area use of reindeer Rangifer tarandus tarandus. We tested the extent to which a WP represented a behavioural barrier for reindeer movement by comparing two neighbouring areas; one peninsula with and one without a WP. Both peninsulas had a parallel road and a power line bisecting them in a north-south direction. Presence of a larger or similar number of reindeer on the outer western compared to the inner eastern sections in both areas indicated no barrier effect from the WP. Furthermore, no clear barrier effects were found for reindeer movements during summer in the WP or neighbouring area, as reindeer have continued to cross back and forth between the inner and outer sections of the two areas. Contrary to our expectation, our finding contrasted with previous studies finding negative barrier effects from linear structures such as power lines and roads, suggesting considerable variation i...

ZnNi/NiP compositionally modulated multilayer (CMM) coatings which have a novel three-dimension (3d) latticed multilayer structure were prepared by dual-bath technique. The formation of the special 3d latticed structure was investigated. The adhesion and corrosion resistance of the CMM coatings were studied. The results showed that the special 3d latticed multilayer structure, which was different from the structure of traditional CMM coatings, was formed during NiP electroless plating. The 3d latticed structure benefited the adhesion and corrosion resistance of the novel CMM coatings. The barrier effect of the 3d latticed structure is enhanced.

Highways constitute barriers to wildlife passage, or permeability, which fragment populations and habitats. The degree of barrier effect caused by roadways varies by wildlife species, highway type and standard, and traffic volume. We assessed deer–highway relationships along a 27-km stretch of highway in central Arizona, USA. Our research objectives were to 1) assess white-tailed deer (Odocoileus virginianus) highway crossing patterns and permeability, 2) compare deer permeability on 4-lane reconstructed and 2-lane control sections to determine the influence of wildlife underpasses, and 3) assess and compare deer passage relationships to traffic volume. We fitted 13 deer with Global Positioning System (GPS) collars between 2004 and 2007. Eleven deer crossed the highway 395 times. On 2 control sections, deer crossed an average of 0.02 times/day, while on 3 reconstructed sections they averaged 15 times more crossings/day (0.28; t13 = −2.35; P = 0.035). The deer passage rate on control sections averaged 0.03 crossings/approach, approximately 20% of that for reconstructed sections (0.16; t13 = −2.43; P = 0.030). We linked hourly traffic volumes to our GPS data to examine how passage rates and the proportion of deer relocations at different distances from the highway varied with traffic volume. Deer distance from the highway showed minimal shift away from the highway with increased traffic, and at-grade passage rates were low (≤0.1 crossings/approach) across all traffic volumes. Although our linear regression analysis found no relationship between deer passage rate and increasing traffic volume on reconstructed sections with underpasses, there was a strong negative relationship on control sections (r = −0.881; P = 0.05); thus, we conclude that deer passage rates were minimally affected by traffic on reconstructed sections where passage structures facilitated below-grade passage. Further, from the 865 deer groups we recorded on videotape at 5 underpasses, traffic levels did not affect below-grade deer passage at the volumes we studied. Passage structures improved highway permeability across reconstructed sections with underpasses where traffic volume had a much lower impact compared to deer crossing at highway grade on control sections. © 2011 The Wildlife Society.

The flammability of various flame-retarded formulations containing different hydrated mineral fillers and/or phosphorous compounds and/or carbon nanotubes has been investigated using both a cone calorimeter and a pyrolysis combustion flow calorimeter (PCFC). A method was proposed to evaluate the barrier effect of the flame-retardant additives. This method is based on the fact that the PCFC is non-sensitive to physical flame-retardant effects whereas both chemical and physical phenomena have a great effect on cone calorimeter results. Therefore, normalized peak of heat release rate (pHRR) values obtained with both techniques do not always show a good correlation. It was highlighted that the mismatch between both pHRR results was related to the formation of a protective layer during combustion. Protective layers have been evidenced independently by visual observations. Thus, it is proposed that the magnitude of the deviation from a perfect correlation between cone calorimeter and PCFC pHRRs could be used to quantify the magnitude of barrier effect. Although the results obtained from different fire tests are generally not correlated, such an approach based on the complementarity of different techniques appears more relevant despite of its empirical nature. Copyright © 2011 John Wiley & Sons, Ltd.

We developed one-dimensional, fully implicit numerical scheme to investigate the dynamic effect in the capillary pressure–saturation relationship used in the modeling of two-phase flow in porous media. Its validity was investigated by means of semianalytical solutions developed by McWhorter and Sunada (1990) and the authors. The numerical scheme was used to simulate a drainage experiment where the sand and fluid properties were known. Then the numerical scheme was used to simulate a laboratory experiment in a homogeneous column, including three major models of the dynamic effect coefficient τ. This numerical scheme can handle porous medium heterogeneity and was used to simulate a fictitious experimental setup with two different sands. As a result, the penetration time of the air phase through a layered porous medium for models including dynamic effects varied between 50 and 150% compared with static models of the capillary pressure–saturation relationship. Additionally, the accumulation time of air at a material interface (i.e., the delay of the air at the interface due to the capillary barrier effect) was investigated as a function of the ratio between the air-entry pressure values of the adjacent sands, emphasizing the differences between the dynamic and static capillary pressure models.

The influence of endothelial cell pumping and of cell barrier functions on cultivated corneas has been studied by comparing the rate of weight increase in freeze-treated, ouabain-treated and fresh corneas. Inhibition of the endothelial cell pump activity increased the swelling rate from 0.5% of start weight per h (fresh corneas) to about 2% per h (ouabain-treated corneas), as measured after 24 h in culture medium. The cell barrier effect was estimated by comparing the swelling rate of ouabain-treated corneas after 24 h, and the swelling rate of freeze-treated corneas with the same swelling pressure. The values are 2 and 9.5% per h, respectively. The swelling rate of freeze-treated corneas with different button diameters was found to increase with decreasing corneal button diameter.

A new multigrid method based on high-order vector finite elements is proposed in this paper. Low-level discretizations in this method are obtained by using low-order vector finite elements for the same mesh. The Gauss–Seidel method is used as a smoother, and a linear equation of lowest level is solved by the ICCG method. But it is often found that multigrid solutions do not converge into ICCG solutions. An elimination algorithm of constant term using a null space of the coefficient matrix is also described. In three-dimensional magnetostatic field analysis, convergence time and number of iteration of this multigrid method are discussed with the conventional ICCG method. © 2009 Wiley Periodicals, Inc. Electron Comm Jpn, 92(1): 39–45, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecj.10228

Collagen membranes cross-linked by glycation (GLYM) for guided bone regeneration (GBR) and guided tissue regeneration (GTR) are used extensively with proven safety and efficacy. Complete GLYM ossification, when placed in contact with bone, was described in a canine jaw model, suggesting that GLYM may serve as an ossification substrate. The purpose of this case series was to histologically evaluate GLYM in GBR procedures in humans.We retrospectively selected seven consecutive patients with implant-related bony defects who underwent GBR with GLYM. Six defects had bone grafts, and one had a barrier alone. Selection criteria were primary closure upon post-surgical examination and tissue that was 2- to 3-mm thick over the implant's cover screw. Tissue was removed when the implants were uncovered after 20 to 29 weeks. Decalcified sections were stained and analyzed under light microscopy.In five of seven specimens, GLYM was identified and preserved its barrier effect. The mean membrane thickness was 0.17 +/- 0.054 mm. In two cases, the bone grafts under the membrane were embedded in new bone, whereas in five cases, they were embedded in fibrous connective tissue. Formation of new dense bone was observed along the side of the membrane facing the original bone, and various degrees of membrane ossification were evident in all five cases.GLYM maintained its barrier effect in five of seven cases for 25 weeks and induced dense new bone along its interface with underlying tissues. To the best of our knowledge, this is the first report on GLYM ossification in humans with direct mineral apposition on glycated collagen and suggests a new concept of tissue-integrated active barriers.

Effects of highway fencing and wildlife crossings on moose (Alces alces) movements and space use in soutwestern Sweden

Summary 1. Roads can act as barriers to animal movement, which may reduce population persistence by reducing recolonization of empty habitats and limiting immigration. Appropriate mitigation of this barrier effect (e.g. seasonal road closures, location and design of wildlife over- or underpasses) depends upon whether the animals avoid the road itself or the traffic on the road. Empirical studies of road avoidance to date do not generally differentiate between these. 2. We conducted short- and long-distance translocations and trapping studies of white-footed mice ( Peromyscus leucopus ) and eastern chipmunks ( Tamias striatus ) near two-lane paved roads, which differed widely in traffic amount, from 47 to 15 433 vehicles per day. 3. In the trapping study (13 sites) only five animals moved across a road, in comparison to 36 animals that moved the same distance without an intervening road ( P < 0·0001). In the short-distance translocations (15 sites), 51% of the small mammals that were translocated across roads returned, in comparison to a return rate of 77% of animals that were translocated a similar distance with no intervening road ( P = 0·009). 4. In the long-distance translocation study (24 sites) we found that each intervening road reduced the probability of successful return by about 50%. 5. We found no significant effects of traffic amount on return rates in either the short-distance or the long-distance translocations studies. 6. Small mammal densities were not lower near roads and we found no evidence for a decrease in density near roads with increasing traffic amount. 7. Synthesis and applications. Our results suggest that small mammals avoid the road itself, and not emissions such as noise from the traffic on the roads. Our results imply that the barrier effect of roads on these species cannot be mitigated by measures aimed at reducing traffic amount; other measures such as wildlife passages would be needed.

in reproductive swards, stems appear to act as vertical or horizontal barriers to bite formation, influencing instantaneous intake rate (IIR). The hypothesis was tested that the stems' barrier effect is determined by the physical properties and density of stems. Artificial microswards, consisting of 20-cm leaves and 15-cm stems of Panicum maximum, were offered to three steers (362 kg) in a factorial combination of three stem densities (0, 100 and 400 stems m(-2)) and two levels of stem tensile resistance [low (LTRS) and high tensile-resisting stems (HTRS)]. LTRS were not a barrier to defoliation and did not affect bite depth and bite mass. HTRS acted as both a horizontal barrier and a vertical barrier depressing bite depth (13.4, 13.6 and 5.1 cut for 0, 100 and 400 stems m(-2), respectively), bite area (89.3, 50.8 and 47.6 cm(2) for 0, 100 and 400 stems M-2, respectively), bite mass (0.51, 0.29 and 0.11 g for 0, 100 and 400 stems m(-2), respectively) and IIR (23.8, 10.5 and 3.6 g sec(-2) for 0, 100 and 400 Stems m(-2), respectively). The results confirmed the importance of the density and physical properties of stems as determinants of the stems' barrier effect on bite dimensions and IIR.

BACKGROUND: The aim of this study was to evaluate the efficacy of a topical hyaluronic acid (HA) preparation (0.2%) in the management of recurrent aphthous ulceration (RAU). METHODS: One hundred and twenty patients with RAU participated in a randomized, placebo controlled, doubleblind trial to evaluate the efficacy of the topical HA and preparation. Outcome measures include soreness relief on immediate application (recorded over 60 min). Thereafter, patients completed a log diary recording soreness from the ulcers, occurrence of new ulcers and ulcer duration. RESULTS: Both topical HA and placebo resulted in a significant reduction in ulcer soreness following immediate application (P = 0.0004). Throughout the rest of the investigation period, there was no significant differences (P > 0.05) between the treatments for reducing soreness. Patients treated with topical HA recorded few ulcers on day 5 of the investigation than those treated with placebo (P < 0.001). Likewise, the occurrence of new ulcers was lower in the HA treated group on day 4 when compared with placebo (P = 0.047). CONCLUSION: Topical HA (0.2%) may be of benefit in the management of RAU. Immediate reduction of symptoms appears to be a barrier effect. J Oral Pathol Med (2006) 35: 461–5

Much remains to be learned about how anthropogenic structures affect migration in large mammals. We examined the potential influence of the international railroad in Mongolia on migration in Mongolian gazelles (Procapra gutturosa). We examined gazelle movements and the normalized difference vegetation index (NDVI) on both sides of the railroad. The tracked gazelles never crossed the railroad, despite movements that mainly followed the railroad in winter and higher NDVI values on the opposite side. It is likely that the railroad had a barrier effect on gazelle migration because it split the gazelles' habitat. Our results, although based on an extremely small sample, have utility in indicating approaches that might be useful for examining migration in ungulates. Resumen: Falta mucho por conocer sobre el efecto de estructuras antropogenicas sobre la migracion de mamiferos mayores. Examinamos la potencial influencia del ferrocarril internacional en Mongolia sobre la migracion de gacelas de Mongolia ( Procapra gutturosa). Examinamos los movimientos de las gacelas y el indice de vegetacion de diferencia normalizada (IVDN) a ambos lados de la via ferrea. Las gacelas rastreadas nunca cruzaron la via ferrea, a pesar de que los movimientos mayormente seguian la via en invierno y que los valores de IVDN eran mayores del lado contrario. Es probable que la via ferrea produjera un efecto de barrera sobre la migracion de las gacelas porque dividio al habitat de las gacelas. Nuestros resultados, aunque basados en una muestra extremadamente pequena, son utiles para senalar estrategias que pueden ser utilizadas provechosamente para examinar la migracion de ungulados.

Osteonal bone is often compared to a composite material and to metals as discontinuities within the material may provide sites of stress concentration for crack initiation and serve as barriers to crack growth. However, little experimental data exist to back up these hypotheses. Fluorescent chelating agents were applied at specific intervals to bone specimens fatigue tested in cyclic compression at a stress range of 80 MPa. The failed specimens were sectioned and labelled microcracks identified using UV epifluorescence microscopy. Microcrack lengths were measured and their relationship to cement lines surrounding secondary osteons recorded. Microcrack length at the time of encountering a cement line was also measured. Microcracks of less than 100mum stopped growing when they encountered a cement line. Microcracks of greater than 100mum in length continued to grow after encountering a cement line surrounding an osteon. Only microcracks greater than 300mum in length were capable of penetrating osteons and these microcracks were the only ones which were observed to cause failure in the specimen. These experimental data support the hypothesis that secondary osteons act as barriers to crack propagation in compact bone. However, it shows that this microstructural barrier effect is dependent on the crack length at the time of encountering an osteon. For the vast majority of cracks, osteons act as barriers to growth but for the minority of cracks that are long enough and do break through the cement line, an osteon may actually act as a weakness in the bone and facilitate crack propagation.

PURPOSE To investigate the influence of storage temperature on corneal swelling and on endothelial morphology in cultured corneas. MATERIAL AND METHODS Forty-eight rabbit corneas were separated into four groups of 12. The corneas were stored in culture medium at 37 degrees (group 37), 34 degrees (group 34), 31 degrees (group 31) and 23 degrees (room temperature) (group 23), respectively. All the corneas were monitored by weight recordings on days 0, 1, 2, 3, 4 and 7. On day 7, corneas were prepared for scanning electron microscopy and endothelial cell counts were performed. RESULTS Lowering the temperature of the culture medium resulted in less swelling. Both temperature and storage time had significant effects on corneal swelling (p < 0.001). On day 7, the observed mean weight increase was 131.2%, 143.0%, 172.5% and 199.7% in groups 23, 31, 34 and 37, respectively. The estimated mean daily weight increase for the corneas were 2.6%, 4.0%, 9.1% and 16.0% in groups 23, 31, 34 and 37, respectively. Scanning electron microscopy showed an intact endothelial layer in all groups after 7 days and there were no statistically significant differences in endothelial counts between groups 23, 31 and 34. In group 37, the cell borders were difficult to distinguish after 7 days and no meaningful count could be performed. CONCLUSIONS The swelling rate of cultured corneas is significantly less at 23 degrees and 31 degrees than it is at 34 degrees and 37 degrees during the first week. This is most likely the result of a greatly increased barrier effect at lower temperatures. Whereas weight recording revealed profound differences between the groups, scanning electron microscopy and endothelial cell counting did not. The results support the hypothesis that storage at 37 degrees is not optimal in culturing corneas. Lowering the temperature below body temperature, and even lower than 31 degrees, results in less corneal swelling.

Distinguishing the different contributions to fatigue damage of short cracks having different sizes and locations on the specimen surface, three new concepts, referred to as effective short fatigue cracks (ESFCs), dominant effective short fatigue cracks (DESFC), and density of ESFCs, respectively, are introduced to facilitate an understanding of the mechanism of interaction and evolution of short cracks. These concepts are interrelated and in conjunction produce an ‘effective short fatigue crack criterion’. Replica observations of 19 smooth axial specimens of 1Cr19Ni9Ti stainless steel weld metal during low-cycle fatigue tests reveal that the short cracks contribute to the fatigue damage of specimens due to the formation of a critical density of ESFCs. The density reflects the local microstructural growth conditions ahead of the DESFC tips. The DESFC behaviour is a result of interactive short cracks, and this behaviour is deemed suitable to describe the collective behaviour of short cracks. In the microstructural short-crack stage, the DESFC are located in the weakest zone. Due to an irregular microstructural barrier effect, the crack density is higher in this zone and increases with fatigue cycling to reach a maximum value at the transition point into the physical short-crack stage. Then, due to the effects of accelerating coalescence and the DESFC size shielding the formation of new cracks, the density decreases rapidly and tends gradually to a saturation value. This is why the short-crack growth rate is high initially and tends gradually to that of long-crack behaviour. The difference and change in local microstructural growth conditions ahead of DESFC tips are the intrinsic cause of the statistical behaviour of short cracks and the scatter of fatigue lives.

Analysis of the data measured by the dynamic stationarized method shows that this method significantly undervalues measured data even on measurement at low k L a values such as 0.06 s -1 , the value common in industry fermentors. It was shown that the maxima revealed by this method in the dependence of k L a on electrolyte (Na 2 SO 4 ) concentration and on surface tension of aliphatic alcohol solutions are not real phenomena but only the result of error in the measurement of k L a.

Numerical simulations were carried out to investigate the capillary barrier effect and the wicking ability of multilayer earth liner systems. Two specific cases were studied: a two-layer liner composed of a fine- over a coarse-textured material, and a three-layer liner composed of a medium-textured material in between a fine- and a coarse-textured material. Results of the simulations show that a quadratic relationship exists between the thickness of the fine-textured material and the arrival time of the wetting front to the interface. At the time the wetting front reaches the interface, the width of the lateral spreading within the fine material is smaller than the thickness of this material. The lateral spreading and thickness are linearly related. The wicking ability of the different materials is more significant under relatively smaller infiltration rates and is controlled by the magnitude of the hydraulic diffusivity. For the two-layer liner the criteria of minimizing the vertical movement and maximizing the wicking effect within the fine-textured material conflict. A three-layer liner satisfies both of these criteria. The results for the three-layer system show that the medium-textured material has more superior wicking properties than the fine material does.

The pathogenesis of venous ulceration is thought to involve the formation of fibrin cuffs around dermal capillaries. Consistent with a barrier effect of fibrin, it has been shown that the dermal diffusion of oxygen, as measured by transcutaneous oxygen pressure (TcPO2), is decreased in limbs affected by venous ulcer. However, it is unknown whether oxygen diffusion around the perimeter of venous ulcers is uniformly affected. In this study, we investigated TcPO2 values at four different quadrants around the ulcers of 14 patients, the contralateral leg of five patients with unilateral ulcers, and the leg of six normal individuals. These values were also compared to TcPO2 measurements at the chest. Our results indicate that, whereas TcPO2 values in limbs affected by venous ulcers are much lower than normal, there is a great deal of variability in oxygen diffusion around individual ulcers. These findings may represent a heterogeneity in the disease process affecting the leg.

Within the framework of appraising the new type of forest damage, the epidermis of two-year-old spruce (Picea abies) needles was investigated as a possible site for primary attack by air pollutants using light and scanning electron microscopy. Depending upon the extent of the macroscopically visible needle leaf disease, a degeneration process of the cuticular, stomatal and epidermal structures leading to the lethal destruction of the needle surface was observed. Stomatal and epidermal cells become increasingly deformed or collapsed showing increasing discolouration due to phenolic deposits. Additionally, the erosion of stomatal waxes is accelerated, leading initially to a temporary occlusion of the stomata, and then to a wide opening of the antechamber following a complete decomposition of the plug. Surface lesions indicating early damage to the epidermal tissue already occur on slightly yellowed needles. The barrier effect of the spruce needle epidermis on exogenous stressors could thereby already be reduced at an early stage, triggering incipient losses of structural resistance. ZusammenfassungVerlust der strukturellen Resistenz in Nadeln geschiadigter Fichten immissionsbelasteter Standorte II. Epidermis und Stomata (Abschlusgewebe) In Zusammenhang mit dem Auftreten neuartiger Waldschaden wurde das Absehlusgewebe zweijahriger Fichtennadeln als vermutlieher primarer Angriffsort fur Luftschadstoffe lichi-undelektronenmikroskopisch uncersucht. In Abhangigkeit von dem Ausmas der makroskopisch sichtbaren Schiaden des Nadelblattes konnte eine Reihung der Degeneration der kutikularen, stomatiaren und epidermalen Strukturen bis hin zu einer vollstandigen Zerstarung der Nadeloberflache vorgenommen werden. Die stomataren und epidermalen Zellen erweisen sich fortschreitend deformiert oder kollabiert und zeigen zunehmende Verfarbungen bedingt durch phenolische Ablagerungen. Weiter findet eine beschleungte Erosion der stomataren Wachse statt, die zuniachst zu einem zeitweiligen Versfhlus der Stomata und schlieslich nach einer volligen Zerstorung des Wachspfropfens zu einer weitgehenden Freilegung des Vorhofes fahrt. Oberflachenlasionen, die friabe Schadigungen des epidermalen Gewebes anzeigen, treten bereits bei geringfiagig vergiibten Nadeln auf. Die absehirmende Wirkung des Abschlusgewebes des Nadelblattes gegeniuber exogenen Stresaoren kann damit bereits auf einer friahen Stufe reduziert werden und dies konnte den Beginn des Verlustes der strukturellen Resistenz auslasen.

The design of existing soil landfill final covers, e.g., a single clay layer cover or a cover with capillary barrier effect (CCBE), aims at limiting water infiltration rather than minimizing landfill gas emissions. We propose an alternative three-layer capillary barrier landfill cover with an added clay layer underneath a CCBE to improve the effectiveness of limiting gas emission. Finite element analyses of coupled water and gas flow were performed to investigate and compare the performance of these three types of soil covers regarding gas emission under a continuous duration of 34 dry d. Due to evaporation, suction in the single clay layer cover increased larger than its air-entry value, causing a significant increase in the air coefficient of permeability. For the CCBE, evaporation also led to water loss in the silt layer, which cannot serve as a gas barrier. On the contrary, the bottom clay in the alternative three-layer capillary barrier cover system was protected by a relatively dry sand layer, which acts as a barrier, minimizing water loss from the clay layer. This is because the dry sand layer has a very low water permeability. As a result, the gas emission rate through the alternative three-layer capillary barrier cover was the lowest among the three types of covers. This rate was lower than the criterion set by the Carbon Farming Initiative, indicating that the alternative three-layer capillary barrier cover is a possible barrier to minimize gas emission even under dry weather conditions.

The influence of a prealloying process on the formation of MoSe2 and thus on the performance of Cu2ZnSnSe4 (CZTSe) solar cells is investigated using sputtering deposition and post-annealing approaches. The dense alloy layer, which is made by a low-temperature prealloying process, acts as a temporary Se diffusion barrier during a subsequent high-temperature selenization process. The formation of thick interfacial MoSe2 can be suppressed effectively by this temporary barrier, cooperating with subsequent quick formation of compact CZTSe layer. The thickness of interfacial MoSe2 layer in CZTSe solar cells can be tailored by adjusting the preannealing process during selenization. As a consequence, the series resistance of CZTSe solar cells is reduced to a low level (≈0.6 Ω cm2), and the performance of CZTSe solar cells is improved significantly. A CZTSe solar cell with efficiency of 8.7% is fabricated.

A model is proposed of mechanisms which might affect the progress of Erysiphe graminis f. sp. hordei in mixtures of barley varieties. Results obtained from two field trials indicate that the efffect of mixtures may be panitioned into three categoriesof the influence of the reduced density of the susceptible plants, the barrier effect of the resistant plants, and the induced resistance due to the non-virulent pathogen biotypes. In the early stages of plant growth the lower density of susceptible plants accounted for most of the reduction in pathogen development in mixtures. As the epidemic progressed, the barrier and induced resistance effects increased in importance and the total mixture effect was at a maximum mid-way through epidemic development. Towards the end of the trials the overall mixture effect declined though the influence of induced resistance was at its maximum. The reasons for these changes and their implications for the use of host varietal mixtures in disease control are discussed. Mixtures also protected the crop against a pathogen other than the target organism.

The dc voltage dependence and the temperature dependence of the current through single grain boundaries in n-type and p-type GaP are investigated. Large-angle grain boundaries show contrary to twin boundaries barrier effect. The current through large-angle grain boundaries at high temperatures is determined by thermionic emission. At low temperatures tunnel currents dominate which seem to be essentially influenced by a thin interlayer between the grains. The transition temperature between the emission and the tunnel regime lies in n-n grain boundaries above and in p-p grain boundaries below room temperature. This is mainly caused by the distinct difference of the barrier heights of n-n and p-p grain boundaries (ϕB,n ≈ 2ϕ B,P).

Es werden die wichtigsten Eigenschaften der verschiedenen Schmutzarten, wie Zusammensetzung und Teilchengrose, die Abhangigkeit der Verschmutzung von der Faserbeschaffenheit — Querschnitt, Faseroberflache und Faserfeinheit — behandelt. Die Hauptgruppe der schmutzabweisenden Ausrustungsmittel basiert auf Pigmenten, wie Titandioxyd, kolloider Kieselsaure und Aluminiumoxyd. Die Wirkung der letztgenannten Gruppe kann mit einer Barrierwirkung verglichen werden, wonach diese Produkte die schmutzaffinen Faserstellen besetzen. Dirtrepulsive Finish of Textiles The important properties of different types of dirt like composition and particlesize as well as the dependence of the contamination on the condition of the fibre, cross section, fibresurface and the fineness of the fibre is dealt with in this paper. The main group of the substances, which make the fibre dirt repulsive, is based on pigments like titanium dioxide, colloidal silicagel and aluminium oxide. The effect of the said group can be compared with a barrier effect as these substances occupy the points of dirtaffinity on the fibre.