Contribution of hardness to the natural resistance of a range of wood species to attack by the marine borer Limnoria

Holzforschung ◽  
2007 ◽  
Vol 61 (2) ◽  
pp. 201-206 ◽  
Author(s):  
Simon M. Cragg ◽  
Cedric Danjon ◽  
Hugh Mansfield-Williams
Keyword(s):  
Wood Species ◽  
Testing Machine ◽  
Surface Hardness ◽  
Significant Negative Correlation ◽  
Natural Resistance ◽  
Feeding Rates ◽  
Production Rates ◽  
Faecal Pellets ◽  
Pellet Production ◽  
Wood Boring

Abstract This study set out to determine whether wood surface hardness plays a role in determining the resistance to Limnoria attack. The feeding rates of the wood-boring crustacean Limnoria quadripunctata on matchstick-sized samples of a range of timbers were assessed by measuring the production of faecal pellets under forced feeding conditions. Pellet production rates varied significantly between wood species, with production on Lophira alata (ekki) 25-fold lower than that on non-durable Scots pine (Pinus sylvestris) sapwood. The surface hardness of the timbers was measured for air-dry and seawater-soaked samples using a microindentation technique. The force required for a universal testing machine to drive a 150-μm-diameter pin 1.2 mm into the samples was measured. For all wood species, the hardness of seawater-soaked wood was lower than that of air-dry wood. Hardness was found to correlate positively with density. Pellet production rates showed a significant negative correlation with hardness across the range of species used, but if the denser species alone were considered, wood species significantly affected the rate, but hardness did not. In view of these observations, tests on resistance to attack by Limnoria should include a denser, non-durable wood species for comparison, as its hardness would likely be more similar to that of the durable species.

Laboratory screening of tropical hardwoods for natural resistance to the marine borer Limnoria quadripunctata: The role of leachable and non-leachable factors

Holzforschung ◽  
2008 ◽  
Vol 62 (1) ◽  
pp. 99-111 ◽  
Author(s):  
Luisa M.S. Borges ◽  
Simon M. Cragg ◽  
Julien Bergot ◽  
John R. Williams ◽  
Ben Shayler ◽  
...  
Keyword(s):  
High Mortality ◽  
Faecal Pellet ◽  
Water Soluble ◽  
Natural Resistance ◽  
Feeding Rates ◽  
Faecal Pellets ◽  
Pellet Production ◽  
Faecal Pellet Production ◽  
Bruguiera Gymnorhiza

AbstractThe marine borerLimnoriaingests essential wood components including the extractives the wood contains. Some extractives may confer borer resistance on certain timbers. Feeding byLimnoriacorrelates with the rate of production of faecal pellets. The faecal pellet production rate and mortality on over 40 test timbers and non-resistantPinus sylvestrissapwood was measured over 15 days. By placing animals in leachate from wood and with wood in flowing seawater, the effects of leaching-resistant and water-soluble compounds were measured. Some previously untested timbers affectedLimnoriaas strongly as timbers reputed for durability in marine construction. Wood ofMinquartia guianensis,Nectandra rubraandBruguiera gymnorhizacaused high mortality, and pellet production on them was less than 10% of production onP. sylvestris. Suppressed feeding rates, but with no heavy mortality, were observed on known durable species such asChlorocardium rodiei,Dicorynia guianensis, Lophira alataandNauclea trillesii, but also onCynometra ananta,Distemonanthus benthamianus,Enterolobium schomburgkii,Goupia glabra,Hymenaea courabil,Mammea africana,Shoreasp. andSacoglottis guianensis. Leachate fromB. gymnorhiza,G. glabra,H. coubaril,N. rubraandShoreasp. caused high mortality. These short-term bioassays thus detected clear differences between wood species in their resistance toLimnoriathat matched findings from long-term marine trials, while indicating new species worthy of detailed testing.

The spatial and temporal distribution of koala faecal pellets

1998 ◽  
Vol 25 (6) ◽  
pp. 663 ◽  
Author(s):  
W. A. H. Ellis ◽  
B. J. Sullivan ◽  
A. T. Lisle ◽  
F. N. Carrick
Keyword(s):  
Significant Relationship ◽  
Average Length ◽  
Temporal Distribution ◽  
Faecal Pellet ◽  
Time Of Day ◽  
Spatial And Temporal Distribution ◽  
Faecal Pellets ◽  
Pellet Production ◽  
South Eastern ◽  
Free Ranging

Faecal pellets were collected under trees used by free-ranging koalas in south-western, central and south-eastern Queensland to determine the spatial and temporal distribution of pellets with respect to the activity of koalas. Deposition of faecal pellets by koalas was analysed according to the time of day at which the tree was occupied. For free-ranging koalas, 47% of daily faecal pellet output was recovered using a collection mat of 8 × 8 m placed under a day-roost tree. The best predictor of pellet production was the presence of a koala in a tree between 1800 hours and midnight. For other periods, there was no relationship between period of tree occupancy and faecal pellet recovery. There was a significant relationship between the average length of tree occupancy and the time of day that a koala entered a tree.

Impact of Different Fiber Reinforcement on Flexural Strength, Fracture Toughness and Abrasive Resistance of Provisional Restorative Resin

2021 ◽  
Author(s):  
Dr. Pratik Bhatnagar
Keyword(s):  
Fracture Toughness ◽  
Carbon Fiber ◽  
Flexural Strength ◽  
Clinical Performance ◽  
Testing Machine ◽  
Surface Hardness ◽  
Abrasive Resistance ◽  
Significance Level ◽  
Post Hoc ◽  
The Impact

Aim: To assess and compare the impact of reinforcement of PMMA with glass fibre, polyethylene fibre and carbon fibres on flexural strength, fracture toughness and abrasive resistance. Background: In view of inadequate mechanical and physical characteristics of PMMA which include low impact strength and low surface hardness and resulting lowered clinical performance of the prosthesis, the study was designed to investigate the impact of reinforcement of PMMA with glass, polyethylene and carbon fibers on flexural strength, fracture toughness and abrasive resistance. Methods and Findings: Rectangular specimens (n=120; 30 each from 4 groups; 65 × 10 × 3.3 mm3) were fabricated and loaded on Universal Testing Machine until fracture for flexural strength and fracture toughness and on Taber Abrasive Tester for abrasive resistance. Data were analyzed using one–way ANOVA followed by Post Hoc test - Bonferroni multiple comparison analysis, using significance level of 0.05. Significant increase in fracture toughness was observed in specimens reinforced with polyethylene and carbon fiber, albeit the values of flexural strength were increased insignificantly. Specimens reinforced with glass and carbon fiber had significantly low values of abrasive resistance. Conclusion: Findings indicate that reinforcement of PMMA by non-specific fibers like glass, polyethylene and carbon resulted in significant increase in fracture toughness and decrease in abrasive resistance.

Properties of New Glass-Ionomer Restorative Systems Marketed for Stress-Bearing Areas

2020 ◽  
Vol 45 (1) ◽  
pp. 104-110 ◽  
Author(s):  
D Fuhrmann ◽  
D Murchison ◽  
S Whipple ◽  
K Vandewalle
Keyword(s):  
Fracture Toughness ◽  
Composite Resin ◽  
Testing Machine ◽  
Surface Hardness ◽  
Glass Ionomer ◽  
Hardness Tester ◽  
Resin Coating ◽  
Significant Difference ◽  
Restorative Materials ◽  
Post Hoc

SUMMARY Objectives: The purpose of this study was to evaluate the properties (fracture toughness, surface hardness) of newer conventional glass-ionomer restorative materials that are marketed for posterior stress-bearing areas compared with more traditional glass-ionomer restorative materials marketed for non–load-bearing areas and composite-resin restorative materials. Methods and Materials: Notched-beam fracture toughness specimens were created in a mold with each tested material (Equia Forte, GC America, with and without a surface coating of Equia Forte Coat; Ketac Universal, 3M/ESPE; ChemFil Rock, Dentsply; Fuji IX GP Extra, GC; Ionostar Molar, VOCO; Filtek Z250, 3M/ESPE; Filtek Supreme Ultra, 3M/ESPE) and fractured using a universal testing machine after 24 hours of storage. Hardness values were determined on the surface of the fracture toughness specimens using a hardness tester. Data were analyzed with a one-way ANOVA and Tukey's post hoc test per property (alpha=0.05). Results: The composite-resin restorative materials had significantly greater fracture toughness than the glass-ionomer materials. There was no significant difference in fracture toughness between the glass-ionomer materials. The use of a resin coating significantly increased the surface hardness of the newer glass ionomer marketed for stress-bearing areas. Conclusions: Fracture toughness was not improved with the newer glass-ionomer restorative materials marketed for stress-bearing areas compared to the conventional glass-ionomer materials, however a resin coating provided greater surface hardness.

Physical Property Evaluation of Four Composite Materials

2013 ◽  
Vol 38 (5) ◽  
pp. E144-E153 ◽  
Author(s):  
M Chang ◽  
J Dennison ◽  
P Yaman
Keyword(s):  
Flexural Strength ◽  
Physical Properties ◽  
Vickers Hardness ◽  
Dwell Time ◽  
Testing Machine ◽  
Surface Hardness ◽  
Composite Resins ◽  
Bending Test ◽  
Polymerization Shrinkage ◽  
Hardness Tests

SUMMARY Purpose The purpose of this study was to evaluate the physical properties of current formulations of composite resins for polymerization shrinkage, surface hardness, and flexural strength. In addition, a comparison of Knoop and Vickers hardness tests was made to determine if there was a correlation in the precision between the two tests. Materials and Methods Four composite resin materials were used: Filtek LS (3M-ESPE), Aelite LS (Bisco), Kalore (GC America), and Empress Direct (Ivoclar). Ten samples of each composite (shade Vita A2) were used. Polymerization shrinkage was measured with the Kaman linometer using 2-mm-thick samples, cured for 40 seconds and measured with digital calipers for sample thickness. Surface microhardness samples were prepared (2-mm thick × 12-mm diameter) and sequentially polished using 600-grit silicone carbide paper, 9 μm and 1 μm diamond polishing solutions. After 24 hours of dry storage, Knoop (200 g load, 15 seconds dwell time) and Vickers (500 g load, 15 seconds dwell time) hardness tests were conducted. Flexural strength test samples (25 × 2 × 2 mm) were stored in 100% relative humidity and analyzed using a three-point bending test with an Instron Universal Testing Machine (Instron 5565, Instron Corp) applied at a crosshead speed of 0.75 ± 0.25 mm/min. Maximum load at fracture was recorded. One-way analysis of variance and Tukey multiple comparison tests were used to determine significant differences in physical properties among materials. Results Filtek LS had significantly lower shrinkage (0.45 [0.39] vol%). Aelite LS demonstrated the greatest Knoop surface hardness (114.55 [8.67] KHN), followed by Filtek LS, Kalore, and Empress Direct (36.59 [1.75] KHN). Vickers surface hardness was significantly greater for Aelite LS (126.88 [6.58] VH), followed by Filtek LS, Kalore, and Empress Direct (44.14 [1.02] VH). Flexural strength (MPa) was significantly higher for Aelite LS and Filtek LS (135.75 [17.35]; 129.42 [9.48]) than for Kalore and Empress Direct (86.84 [9.04]; 92.96 [9.27]). There is a strong correlation between results obtained using Knoop and Vickers hardness tests (r=0.99), although Vickers values were significantly greater for each material. Conclusion Results suggest that Aelite LS possesses superior hardness and flexural strength, while Filtek LS has significantly less shrinkage compared with the other composites tested.

Decay susceptibility of Amazon wood species from Brazil against white rot and brown rot decay fungi 10th EWLP, Stockholm, Sweden, August 25–28, 2008

Holzforschung ◽  
2009 ◽  
Vol 63 (6) ◽  
Author(s):  
Jane Silveira Carneiro ◽  
Luciano Emmert ◽  
Gerson H. Sternadt ◽  
Julio César Mendes ◽  
Getúlio F. Almeida
Keyword(s):  
Wood Species ◽  
Wood Decay ◽  
Brown Rot ◽  
White Rot ◽  
Natural Resistance ◽  
Decay Fungi ◽  
Pycnoporus Sanguineus ◽  
Hymenaea Courbaril ◽  
Weight Losses ◽  
Resistant Species

Abstract A total of 28 tropical Amazon woods – many of them rarely used – from Tapajós National Forest, Pará state, Brazil, were tested for their natural resistance against the decay fungi: Ganoderma applanatum, Trametes versicolor, Pycnoporus sanguineus, Meruliporia incrassata, and Gloeophyllum trabeum. The wood resistance classification was made according to the ASTM D 2017-81 method. High variability on susceptibility to wood decay fungi was found. Their mean weight losses varied from 0.6% to 45.6%. Highly resistant species include: Astronium gracile, Bagassa guianensis, Caryocar villosum, Claricia racemosa, Diplotropis purpurea, Dipteryx odorata, Hymenaea courbaril, Manilkara huberi, Mezilaurus itauba, Sextonia rubra, Tabebuia incana, and Vatairea paraensis. The following wood species are less durable: Brosimum parinarioides, Jacaranda copaia, Laetia procera, Pouteria pachycarpa, Virola caducifolia, and Trattinnickia rhoifolia. Meruliporia incrassata caused extensive weight losses in most of the investigated Amazon wood species.

scholarly journals Effect of Incorporation of Disinfectants on Surface Hardness and Dimensional Accuracy of Die Stone: An in vitro Study

2017 ◽  
Vol 7 (3) ◽  
pp. 86-91
Author(s):  
Anubhuti Bakshi ◽  
Rajat Dang
Keyword(s):  
Sodium Hypochlorite ◽  
Testing Machine ◽  
Surface Hardness ◽  
In Vitro Study ◽  
Dimensional Accuracy ◽  
Control Group ◽  
Time Interval ◽  
Type Iv ◽  
Post Hoc

ABSTRACT Aim To evaluate surface hardness and dimensional accuracy of type IV dental stone after incorporation of disinfectants. Materials and methods A total of 100 specimens, 50 (40 mm⨯ 10 mm) disk shaped and 50 frustum cone shaped, were fab- ricated from type IV dental stone after incorporation of various disinfectants, namely glutaraldehyde (2%), iodophor (1.76%), chlorhexidine (2%), and sodium hypochlorite (1%), for evaluation of surface hardness and dimensional accuracy. Surface hardness was tested after 1- and 24-hour time interval using Rockwell hard- ness testing machine. Dimensional accuracy was measured using traveling microscope. Data obtained were compiled and analyzed statistically by using analysis of variance and post hoc test. Results Results showed significant decrease in surface hard- ness of samples incorporated with disinfectants at 1 hour as compared with control (distilled water). Surface hardness of all the samples increased with time and was almost equal to control group at 24-hour interval, with iodophor showing the maximum value in comparison with the other disinfectants used. When dimensional accuracy of all the groups was compared, iodophor and sodium hypochlorite were found to cause negative alterations. Conclusion Within the limitations of this in vitro study, it was concluded that incorporation of disinfectants in die stone during mixing did not affect the hardness value at 24-hour interval. Dimensional accuracy was altered by iodophor and sodium hypochlorite, but remained unaffected by chlorhexidine and glutaraldehyde. How to cite this article Bakshi A, Dang R. Effect of Incorpo- ration of Disinfectants on Surface Hardness and Dimensional Accuracy of Die Stone An in vitro Study. Int J Prosthodont Restor Dent 2017;7(3):86-91.

scholarly journals Leptine-based Resistance to Colorado Potato Beetle among Interspecific Hybrids of Wild Potato

HortScience ◽  
1995 ◽  
Vol 30 (4) ◽  
pp. 819F-819 ◽  
Author(s):  
Anusuya Rangarajan ◽  
A. Raymond Miller ◽  
Richard Veilleux
Keyword(s):  
Colorado Potato Beetle ◽  
Solanum Chacoense ◽  
Natural Resistance ◽  
Pesticide Use ◽  
Feeding Rates ◽  
Insect Feeding ◽  
Factors Affecting ◽  
Potato Beetle ◽  
Cultivated Potatoes ◽  
Leaf Disks

Leptine (LP) glycoalkaloids have been demonstrated to confer natural resistance to the Colorado potato beetle (CPB) in Solanum chacoense (chc). Development of cultivated potatoes with natural resistance to CPB has the potential to reduce both costs and environmental impacts of production by reducing pesticide use. To introgress the genes conferring leptine production from chc into S. tuberosum (tbr), clones of chc have been crossed with clones of S. phureja. Leaf disks from eight hybrids were subjected to a CPB second instar feeding bioassay to determine if extent of feeding was related to LP levels. Most hybrids contained leptinidine (LD, the aglycone of LP) levels intermediate to chc and tbr, and insect feeding was suppressed 30% to 50% in hybrids containing >10 mg·g–1 DW LD. One hybrid displaying feeding suppression contained a very low level of LD, whereas another hybrid that contained higher levels of LD had higher feeding rates. The presence of LD at “threshold” levels in these hybrids will suppress feeding of CPB, but other factors affecting resistance are also present and need to be explored.

scholarly journals Coleoborers (Curculionidae: Scolytinae) in native and homogeneous systems of Brazil nut (Bertholletia excelsa bonpl.) in the Southern Amazon, Brazil

PLoS ONE ◽  
2021 ◽  
Vol 16 (1) ◽  
pp. e0234287
Author(s):  
Marcus Henrique Martins e Silva ◽  
Juliana Garlet ◽  
Fernando Luiz Silva ◽  
Carla da Silva Paula
Keyword(s):  
Production Systems ◽  
Management Strategies ◽  
Significant Negative Correlation ◽  
Economic Damage ◽  
Brazil Nut ◽  
Important Species ◽  
Homogeneous Systems ◽  
And Cluster Analysis ◽  
Amazonian Brazil ◽  
Wood Boring

Brazil nut is one of the most important species of the Amazon due to its socioeconomic importance. Especially in homogeneous production systems, it may be susceptible to damage by wood-boring insects, as by the subfamily Scolytinae (Coleoptera: Curculionidae); thus, inadequate management conditions can cause economic damage. Therefore, the objective of the present work is to evaluate the occurrence of wood-boring insects (Curculionidae: Scolytinae) in native and homogeneous systems of Brazil nut in the Meridional Amazonian, Brazil. The study was conducted in three environments: Brazil Nut Native Anthropized, Homogeneous Brazil Nut and Brazil Nut Native Preserved. Twelve ethanol (96° GL) traps were installed in each environment during four sampling periods. The data were submitted to entomofaunistic analysis, Pearson´s correlation analysis and cluster analysis. A total of 2,243 individuals from 31 species were sampled, of which 23 were from the Brazil Nut Native Anthropized nut, 24 from the Homogeneous Brazil Nut and 26 from the Brazil Nut Native Preserved. Some species are restricted to a specific environment, such as Corthylocurus vernaculus Wood & Bright, 1992 and Xyleborus biconicus Eggers, 1928, in relation to Brazil Nut Native Anthropized, Xyleborus tolimanus Eggers, 1928 that occurred only in Homogeneous Brazil Nut and Corthylus antennarius Schedl and Hypothenus bolivianus Wood & Bright, 1992 verified only in Brazil Nut Native Preserved. In the faunistic analysis, we highlight the species Xyleborus affinis (Eichhoff, 1868), which was the most representative one in the three environments and a super-dominant species in all four sampling periods. Among the species considered indicator due to their high representativeness in the sampling, only Premnobius cavipennis Eichhoff, 1878 showed a significant negative correlation between its abundance and the minimum temperature for environments Homogeneous Brazil Nut and Brazil Nut Native Preserved. There was a greater similarity between the Brazil Nut Native Anthropized and the Brazil Nut Native Preserved; these two environments showed dissimilarity with the Homogeneous Brazil Nut. Monitoring wood-boring insects in Brazil nut agroecosystems is fundamental for the establishment of integrated pest management strategies.

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