The identification of fracture in dried wood based on theoretical modelling and acoustic emission     

Stefan?Jan?KowalskiEmail author  Waldemar?Moliński  Grzegorz?Musielak 《Wood Science and Technology》2004,38(1):35-52

Physical interpretation of the three characteristic groups of acoustic signals emitted during convective drying of wood is the main subject of this paper. The acoustic emission (AE) was to evidence the fracture intensity during drying of a birch wood sample of cylindrical shape. To explain the three characteristic groups of acoustic signals, and particularly the last one, a mechanistic model of drying was applied to analyse the drying induced stresses in the tested sample. One can conclude from this analysis that the third group of acoustic signals arises when the surface stop to shrink and the wet core (initially in compression) begins to dry. The shrinkage of the core causes compression of the boundary layer and tension of the core. Thus, the reverse of the stress signs in the cylinder cross-section takes place and this possibly involves the destruction of wood structure in the tensed core.  相似文献   

Effects of helical angle of router bit on acoustic emission     

Grzegorz Cyra  Chiaki Tanaka  Masahiro Yoshinobu  Yoshihiko Nishino 《Journal of Wood Science》1998,44(3):169-176

The purpose of this study was to investigate the effects of changes in the helical angle of the router bit on the acoustic emission (AE) signal for various workpiece grain angles. The helical angle varied from 0° to 50° at 10° increments. The workpiece grains were oriented from 0 degrees (cutting parallel to the grain), through 90° (cutting end of the grain), to 165° at 15° increments. The AE signals and machined surface roughness were measured in an attempt to clarify the relations between them. The results were summarized as follows: (1) The AE signals were lowest in the with the grain cutting zones and slightly increased in the against the grain cutting zones; they rapidly reached the highest values at the 135°–165° grain angles. The greater the helical angle of the router bit, the smaller were the AE count rates for each grain angle investigated. There was no significant change in AE generation for helical angles of 0° and 10°. Moreover, the greater the feed rate, the greater was the AE count rate for every cutting condition investigated. (2) The surface roughness, similar to the AE count rate, had the lowest values in the with the grain cutting zones, slightly increased until the 120° grain angle, and then rapidly become extremely rough, reaching a maximum at the grain angles of 135°–150°. There was no remarkable change in the machined surface roughness while routing with the grain using the router bit of greater helical angle. However, when routing against the grain, the greater the helical angle the smoother was the machined surface. (3) There were correlations between the AE count rate and the machined surface roughness for each helical angle investigated. Therefore, acoustic emission has shown promise for monitoring and controlling the routing operation, including various grain angles and helical angles of the router bit.  相似文献   

Effects of sharp eyespot (Rhizoctonia cerealis) on yield and grain quality of winter wheat   总被引：1，自引：0，他引：1  

Grzegorz Lema��czyk  Hanna Kwa?na 《European journal of plant pathology / European Foundation for Plant Pathology》2013,135(1):187-200

Sharp eyespot caused by Rhizoctonia cerealis was assessed in four winter wheat crops surveyed at four locations in north-central Poland in 2006?C2009. At the four locations symptoms developed on 41.9?C67.7?% of shoots of all plants (average of 4?years) and on 49?C73.5?% of shoots of diseased plants (average of 4?years). Slight (category 1) disease was most frequent, occurring on 24.4?C41.3?% of shoots (range 14.8?C51.3?%); moderate (category 2) disease was less frequent, occurring on 16.9?C25.5?% of shoots (range 8.9?C32.4?%); severe (category 3) disease was least frequent, occurring on 3.2?C7.1?% (range 0?C22.0?%) of shoots. Sharp eyespot affected wheat growth and yield, and grain quality. Disease, especially in the severe category, was associated with significant decreases in plant and ear dry weights, number of grains per ear, grain dry weight per ear and thousand-grain weight, and with increases in grain protein and wet gluten contents, Hagberg falling number and sedimentation value. There was an association between occurrence of sharp eyespot in stems and colonization of grain by fungi. Alternaria alternata and E. nigrum were the most common species.  相似文献   

Rapid detection of Marek's disease virus in feather follicles by loop-mediated amplification     

Woźniakowski G  Samorek-Salamonowicz E  Kozdruń W 《Avian diseases》2011,55(3):462-467

Marek's disease (MD) remains a serious problem in the production of poultry. The disease is caused by Marek's disease virus (MDV), and despite the ubiquitous use of vaccination to control losses, MD still affects poultry farming worldwide. The aim of this study was to develop a loop-mediated isothermal amplification (LAMP) method for the simple and inexpensive detection of MDV in feather tips of chickens. Two pairs of specific primers complementary to the meq oncogene of MDV were designed, targeting the sequence of the very virulent MDV strain, RB1B. Bst polymerase was used for the isothermal amplification of viral DNA at 65 C for 90 min in a water bath. The fluorescence signal was identified in MDV-positive samples after the addition of SYBR Green and ultraviolet (UV) illumination. The sensitivity of LAMP was 2 log 10 plaque-forming units (PFU)/ml of HPRS16 and 10(3) copies/il of plasmid containing the target gene (meq) and was equal in sensitivity to PCR amplification. Due to the use of three sets of primers, LAMP was highly specific for MDV-1 DNA. The developed LAMP technique is a rapid and simple tool for the specific detection of MDV in samples of feathers taken from live chickens. Since the use of thermocyclers is not necessary for LAMP assay, it can be conducted by small laboratories and even field veterinarians.  相似文献   

Broad Coal Tar Biodegradative Potential of Rhodococcus erythropolis B10 Strain Isolated from Former Gasworks Site     

Grzegorz Pasternak  Piotr Rutkowski  Ewa ?liwka  Barbara Ko?wzan  Justyna Rybak 《Water, air, and soil pollution》2011,214(1-4):599-608

Coal carbonization by-products contain up to 10,000 aliphatic and aromatic compounds. Many of them show toxic, mutagenic, and carcinogenic character. In this study, we examined 51 pure bacterial cultures of their ability of coal tar constituent biodegradation. Bacterial cultures were isolated from both explosives and coal tar-contaminated areas. Among all of the investigated strains, 19 showed biodegradative activity. One of the isolates degraded 40% of the substrate in 14 days at a temperature of 15°C. The most active strain was identified by both classic and 16S ribosomal DNA sequencing methods and designated Rhodococcus erythropolis B10. The biodegradation of coal tar constituents, performed by identified strain, was assessed by GC/MS technique. The comparison of samples analyzed by GC/MS before and after biodegradation indicated high degradative potential of the chosen strain. It was able to degrade n-paraffins, n-olefins, benzene, alkylbenzenes, cadalene, and other PAHs, as well as recalcitrant heterocyclic compounds dibenzofuran and its methyl-substituted derivative. The B10 strain isolated and tested in this research shows promising possibilities to be used in field conditions. The biodegradation experiments indicated that satisfactory results may be obtained even in pure bacterial cultures.  相似文献   

Impact of long‐term mineral and organic fertilizer application on the water stability,wettability and porosity of aggregates obtained from two loamy soils          下载免费PDF全文

H. Czachor  M. Charytanowicz  S. Gonet  J. Niewczas  G. Jozefaciuk  L. Lichner 《European Journal of Soil Science》2015,66(3):577-588

The impact of fertilizer application on soil aggregate stability is of increasing interest to soil scientists. Aggregate water stability depends primarily on soil organic matter. We studied silty loam and loamy sand aggregates from three long‐term fertilizer treatments (control, pig manure and NPK) which significantly altered the quantity of organic matter. A new approach to examining aggregate stability was used: soil aggregates were immersed in methanol‐water solutions with methanol at 0, 20, 40 and 60% concentration (C), and non‐disrupted aggregates were separated after 30 minutes. The aggregate resistance R(C) against each solution was taken as the percentage of stable aggregates. Overall resistance of the aggregates was taken as the R_tot parameter given by the product of four R(C) values. The R(C) values of all aggregates were positively correlated with C. The R(60) values were independent of the applied fertilizer. The R(0) value for silty loam aggregates ranged from 28% (pig manure) to 7% (NPK), while that for loamy sand equalled 7–9% in all cases. The R(20) values were most effective at differentiating the soils and the fertilizer treatments. However, the R_tot value was a better indicator of aggregate stability. Greater differences in stabilities of aggregates were noted in loamy sand. Mineral fertilizer application seemed to decrease aggregate resistance in both soils. Total organic carbon and nitrogen content in all non‐disrupted aggregates were negatively correlated with methanol concentration (C) of the solution applied for aggregate separation. The largest decrease was for the pig manure treatment, and the smallest was for the control. Porosity and pore size distributions of the aggregates were derived from micro‐tomography and approximated to lognormal pore size distributions. Larger porosities and pores were found in water‐stable aggregates than in methanol‐stable aggregates. It seems that the dominant mechanisms for aggregate instability during fast wetting were not related only to the pore air compression, but to weakening of attractive forces between aggregate particles by water.  相似文献   

Ubiquitin-binding domains in Y-family polymerases regulate translesion synthesis   总被引：1，自引：0，他引：1  

Bienko M  Green CM  Crosetto N  Rudolf F  Zapart G  Coull B  Kannouche P  Wider G  Peter M  Lehmann AR  Hofmann K  Dikic I 《Science (New York, N.Y.)》2005,310(5755):1821-1824

Translesion synthesis (TLS) is the major pathway by which mammalian cells replicate across DNA lesions. Upon DNA damage, ubiquitination of proliferating cell nuclear antigen (PCNA) induces bypass of the lesion by directing the replication machinery into the TLS pathway. Yet, how this modification is recognized and interpreted in the cell remains unclear. Here we describe the identification of two ubiquitin (Ub)-binding domains (UBM and UBZ), which are evolutionarily conserved in all Y-family TLS polymerases (pols). These domains are required for binding of poleta and poliota to ubiquitin, their accumulation in replication factories, and their interaction with monoubiquitinated PCNA. Moreover, the UBZ domain of poleta is essential to efficiently restore a normal response to ultraviolet irradiation in xeroderma pigmentosum variant (XP-V) fibroblasts. Our results indicate that Ub-binding domains of Y-family polymerases play crucial regulatory roles in TLS.  相似文献   

Ovarian fluid pH enhances motility parameters of rainbow trout (Oncorhynchus mykiss) spermatozoa     

Mariola Wojtczak  Grzegorz J. Dietrich  Mariola S&#x;owi&#x;ska  Stefan Dobosz  Henryk Ku mi&#x;ski  Andrzej Ciereszko 《Aquaculture (Amsterdam, Netherlands)》2007,270(1-4):259-264

All evidence to date suggest that sperm motility is the primary determinant of fertilization success in externally fertilizing fish species. Ovarian fluid, which comprises 10–30% of the total egg volume in salmonids, enhances sperm motility with respect to swimming speed, trajectory and the duration of movement. It was recently demonstrated that there is individual variability in sperm motility enhancing potential of ovarian fluid of particular females. In the present study we examined the effect of particular ovarian fluids collected from 31 females on the sperm motility parameters of one male of rainbow trout (Oncorhynchus mykiss) using computer-assisted sperm analysis (CASA). During our experiment we also monitored the pH of ovarian fluid. We found that particular fluids differed in the ability to activate spermatozoa; sperm remained immotile in four fluids and exhibited 50–100% motility in 27 samples. The percentage of motile sperm, velocity and duration of movement positively correlated with ovarian fluid pH (r² = 0.34–0.62). These data strongly suggest that the pH of the ovarian fluid is the primary determinant of sperm motility in rainbow trout under natural conditions of fertilization.  相似文献   

Modelling Habitat Suitability for Deciduous Forest Focal Species – A Sensitivity Analysis using Different Satellite Land Cover Data     

Michael?G.?MantonEmail author  Per?Angelstam  Grzegorz?Mikusiński 《Landscape Ecology》2005,20(7):827-839

We explored the usefulness of three satellite land cover data sets available to land managers in south-central Sweden for conservation planning using four deciduous forest focal resident bird species with different habitat requirements. Habitat suitability models using empirical species-specific habitat parameters and a Geographic Information System were applied to evaluate and compare the degree of consistency among three different land cover data sets. The study area encompassed 10,000 km² in a landscape mosaic of managed boreal forests and is within the distribution range of all four focal species. Although the three land cover data sets indicated similar total amounts of deciduous forest, the habitat suitability models showed that different land cover data yielded inconsistent results regarding the amount and distribution of suitable habitat within 5×5 km grid cells. Given this sensitivity to the choice of land cover data sets, the habitat suitability models showed positive relationships among the selected focal species for each land cover data set separately. As expected, decreasing amounts of suitable habitat were identified for species with higher specialisation. Thus, because habitat suitability models are an appropriate way to gain insight into the functionality and connectivity of habitat networks, land cover data must be carefully evaluated and if necessary combined with other landscape information for effective conservation planning.  相似文献   

Genetic and pathogenic diversity of Pseudomonas syringae strains isolated from cucurbits     

Renata Słomnicka  Helena Olczak-Woltman  Grzegorz Bartoszewski  Katarzyna Niemirowicz-Szczytt 《European journal of plant pathology / European Foundation for Plant Pathology》2015,141(1):1-14

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