Modeling internal temperature changes of timber poles during ACA treatment

Summary The temperature-time-location relationships during steam conditioning and pressure treatment of timber poles using ammoniacal copper arsenate (ACA) have been studied and a new mathematical model that incorporates both the thermal properties of the poles and the parameters of the treatment process is discussed. Prediction equations and charts are presented that show the minimum required steaming time to satisfy the 1982 Rural Electrification Authority (REA) purchase specification, i.e. a center temperature above 150 °F (65.5 °C) for 2 hours. A six hour steaming time, commonly used for ACA treatment, has been found to be too short to bring poles with diameters larger than about 40 cm to the required sterilization conditions. Therefore longer steaming times, predicted using the methods given here, are recommended. The temperature of the preservative used does not appear to be a major factor in determining the maximum temperature achieved at the center of a pole, but it can influence the length of time the pole is above 65.5 °C.Symbols D pole diameter, cm - k₁ rate of surface temperature change during vacuuming, °C/h - K₂ rate of surface temperature change early in the pressure period, °C/h - J₀ Bessel function of the first kind of order zero - J₁ Bessel function of the first kind of order one - r radial location in a pole measured from the center, cm - R pole radius, cm - T interior temperature of a pole during preservative treatment, °C - T_f final preservative temperature, °C - T_mid average of the steam and the final preservative temperatures, °C - t₀ initial temperature of a pole, °C - T_s temperature of the steam used for conditioning the poles, °C - T₁ surface temperature at the end of the vacuum period, °C - t time measured from the opening of the steam valve for steaming, h - t_above time the center of a pole remained above 65.5°C during preservatives treatment, h - t_c1 total time required for the surface temperature to reach T_f, °C - t_pr time elapsed at which initial vacuuming stops and pressure is applied, h - t_stm minimum required steaming time used, h - t_vc time elapsed at which initial vacuuming starts, h - thermal diffusivity, cm²/h - _n Roots of a particular characteristic equation - _d the time delay period between initial flow of steam and surface temperature response, h     

Gas exchange,water relations and morphology of yellow-cedar seedlings and stecklings before planting and during field establishment

Information is lacking on how yellow-cedar (Chamaecyparis nootkatensis (D. Don.) Spach) stecklings compare with seedlings in their response to potentially limiting field site environmental conditions. Before planting, yellow-cedar seedlings and stecklings were characterized at 5 and 22°C root temperatures for gas exchange parameters (n=6), root growth capacity (n=12) and plant water movement (n=6) using a fully randomized design in a controlled environment growth room. Seedlings, compared with stecklings (t-test), showed a faster (p=0.01) recovery of net photosynthesis (P_n) and stomatal conductance (g_wv) after root temperature increased from 5 to 22°C. Seedlings had greater (p=0.05) root growth capacity (number of new roots 0.5 cm in length) than stecklings after 14 days at 22°C and after 14 days at 5°C followed by 15 days at 22°C. Seedlings had a lower (p=0.01) resistance to plant water movement measured after 29 days (14 days at 5°C followed by 15 days at 22°C root temperature).Seedlings and stecklings were planted on a coastal British Columbia field site and monitored for 1) morphological development and physiological response to ambient site conditions throughout the first growing season, and 2) physiological response to drought conditions during late summer. Both trials used a fully randomized design and stock type means were compared using t-tests (p=0.10, 0.05, and 0.01). Initially, seedlings were taller (p=0.01) than stecklings but otherwise morphologically similar (n=20). Over a 35 week period after planting, stecklings had greater incremental height growth, while seedlings produced a greater (p=0.01) number of roots extending out of the root plug. Seedlings and stecklings (n=6) had similar P_n and g_wv patterns under late spring environmental conditions. However, seedlings had greater P_n and g_wv under cold temperature (p=0.05 and p=0.1, respectively) and drought conditions (p=0.05 and p=0.01, respectively), but during conditions of high evaporative demand and adequate soil moisture, stecklings had greater (p=0.01) P_n and g_wv. Seedlings had higher (p=0.01) daily integrated shoot water potential values (D) at different times during the growing season, and maintained higher (p=0.05) predawn (_pd) shoot water-potential values, higher (D) (p=0.01) and lower (p=0.01) resistance to plant water movement (R_SPAC) during drought conditions.     

Effect of temperature on development and fecundity of Aphis gossypii Glover (Homoptera: Aphididae) on cucumber

The developmental time, survivorship and reproduction of Aphis gossypii Glover was evaluated on detached cucumber leaves at nine constant temperatures ranging from 15±1°C to 35±1°C in 2.5°C increments in the laboratory. Developmental periods of immature stages ranged from 10.8 days at 15°C to 4.1 days at 30°C and 32.5°C. Constant 35°C was lethal to immature stages of A. gossypii. The lower developmental threshold for the cotton aphid was estimated at 6.0°C and it required 92.6 degree–day development for a first instar to become adult. The average reproduction rate was 82.1 nymphs female^–1 at 25°C and 2.3 nymphs female^–1 at 32.5°C. The mean generation time of the population ranged from 6.8 days at 32.5°C to 22.8 days at 15°C. The highest per capita growth rate (r_m=0.526) occurred at 25°C and the lowest at 15°C (r_m=0.208) and 32.5°C (r_m=0.132). It was evident that temperatures over 30°C prolonged development, increased mortality of immature stages, shortened adult longevity and reduced fecundity. The optimal range of temperature for population growth of A. gossypii on cucumber was very broad and ranged between 22.5°C and 30°C.     

Preservative treatment of wood-based composites with 3-iodo-2-propynyl butylcarbamate using supercritical carbon dioxide impregnation

Five structural-use wood-based composites [medium density fiberboard (MDF), hardwood plywood, softwood plywood, particleboard, oriented strand board (OSB)] were treated with 3-iodo-2-propynyl butylcarbamate (IPBC) using supercritical carbon dioxide (SC-CO₂) as a carrier solvent. Treatment was conducted at 35°C/7.85MPa (80kgf/cm²), 35°C/9.81MPa (100kgf/cm²), 35°C/11.77MPa (120kgf/cm²), 45°C/7.85MPa, 45°C/9.81MPa, 45°C/11.77MPa, 55°C/7.85MPa, 55°C/9.81MPa, and 55°C/11.77MPa. A decay test was carried out in the laboratory according to the modified Japanese standard method in which untreated and treated specimens were exposed for 12 weeks to a monoculture of the white-rot fungus Trametes versicolor (L.: Fr.) Pilat or the brown-rot fungus Fomitopsis palustris (Berk. et Curt.) Gilbn. and Ryv. IPBC/SC-CO₂ treatment protected the treated materials from decay by the two fungi, although the relative efficiency against decay varied with the treatment conditions and the type of wood-based composite. Better performance for MDF, hardwood plywood, and particleboard was generally obtained at high temperatures and pressures, whereas softwood plywood and OSB were most protected at low temperatures under any of the pressure levels tested.Part of this work was presented at the 52nd Annual Meeting of the Japan Wood Research Society, Gifu, April 2002     

Bending creep behavior of Acer Saccharum marsh veneered medium-density fiberboard composite

Summary This study was to determine the effects of shelling ratio (SR) 0.200, 0.314, and 0.400, relative humidity (RH) 50, 64, 78, and 92 percent, and temperature (T) 10°C, 24°C, and 38°C, on the initial elastic (Y_E) deformation, irrecoverable creep (Y_IR) and creep deformations (Y_C) of sugar maple-veneered-medium-density fiberboard (MDF) composite panels 16 mm thick, 229 by 584 mm in size for the purpose of developing a hardwood composite. This composite would possess creep resistance comparable to conventional softwood plywood and lumber. The Y_E, Y_C, and Y_IR of all composite panels were significantly (at 0.05 level) affected by the SR, RH, and T in this study. However, no differences in creep deformations were found in all specimens between the SR of 0.314 and 0.400, between the RH of 50 and 64 percent, and between the T of 10°C and 24°C conditions. Composite panels with an SR value of 0.314 and 0.400 had Y_C values approaching that of maple lumber. Panels with SR value of 0.200 displayed lower average Y_E, Y_C, and Y_IR values than those of the Douglas-fir plywood. The effect of T on creep deformation was small when compared to the effects of SR and RH. The Y_IR accounted for almost 2/3 of the Y_C for all composite panels. Predicted Y_E, Y_C, and Y_IR values obtained from the multiple regression models predict very well the observed test values. The creep behavior of the composites was explained well by a power-law equation in log-log form for periods of 2 to 10 minutes and 10 to 100 minutes. Reasonable approximations of Y_C at 2-week intervals were made by extrapolating the short-term creep test results of 10 to 100 minutes log-log regression analysis oor the veneered-MDF composites.     

Study of hydration behavior of wood cement-based composite II: effect of chemical additives on the hydration characteristics and strengths of wood-cement composites

The influence of the 30 chemical additives on the hydration characteristics of birch wood-cement-water mixture was determined by measuring the maximum hydration temperature (T _max) and the time (t _max) required to reach the temperature. The chemical additives were tested and divided into two types depending on the pattern of exothermic reaction peak within the 24-h observation period. The wood-cement-water mixtures with additions of each of the 11 type I chemical additives showed a two-peak temperature-time curve similar to that for neat cement. CaCl₂, FeCl₃, and SnCl₂ reached the highestT _max above 50°C. When the 19 type II chemical additives were included, the mixtures offered only one peak hydration temperature-time curve. Among them, the 10 chemical additives caused an obvious temperature increase at the beginning of the hydration reaction. The most significant effect was with the addition of diethanolamine, where the mixture produced aT _max above 50°C. The strength values (modulus of rupture, internal bond strength) of word-cement board were tested with separate additions of the 10 chemical additives arranged by the highestT _max. There was a good positive correlation betweenT _max and the strength values. In addition, the composite chemical additives were preliminarily examined to determine if they accelerated the hydration reaction of blast-furnace slag cement. The results revealed that composite chemical additives evidently accelerated the hydration reaction and the setting of blast-furnace slag cement mixed with wood. Blast-furnace slag cement can thus be considered for use as an acceptable inorganic bonding material for wood-cement panel manufacture.Part of this report was presented at the 49th Annual Meeting of the Japan Wood Research Society, Tokyo, April 1999     

Determining suitability of thermal development models to estimate temperature parameters for embryonic development of <Emphasis Type="Italic">Sitona lepidus</Emphasis> Gyll. (Coleoptera: Curculionidae)

The clover root weevil, Sitona lepidus Gyll. is a pest of clovers (Trifolium spp.), particularly white clover (T. repens). Larva feeding severely impairs the capacity of white clover to fix atmospheric nitrogen, by attacking the nitrogen-fixing root nodules. Development of the egg stage was studied at six different constant temperatures ranging from 9 to 30°C to improve the basis for phenological forecasts. Development occurred over the entire range of temperatures, although hatching percentage at 30°C was only 24.4% compared to 90.1% at 28.5°C. Developmental time decreased with increase in temperature from 9 to 28.5°C but increased markedly at 30°C. At 28.5°C, the embryo development period was the shortest (10.35 days); whereas at 9°C, this parameter was the longest (55.08 days). Using linear regression, the lower threshold temperature was calculated 4.38°C and the thermal constant was 236.45 degree-days. The relationship between constant temperature and developmental rate was evaluated using nine models. The suitability of the models was evaluated based on eight indicators (R ², RSS, R _adj², AIC, BIC, AICC, W _j , and Z _i ). Of the nonlinear models, the Logan-6, Sharpe and DeMichele, and Lactin models were the most accurate at calculating t _opt of 27, 27.50, and 28°C, respectively. The results suggest that of the three models (Lactin, Briere, and Hilbert and Logan), that estimated critical temperatures, (t _min, t _opt, and t _max), Lactin gave the most suitable fit of data. This response of S. lepidus to temperature can be used for developing phonological models to predict the timing of egg hatch which are important for management programs targeting the weevil.     

Bending creep behavior of hot-pressed wood under cyclic moisture change conditions

This study examined the bending creep behavior of hot-pressed wood during cyclic moisture changes. Sugi (Cryptomerica japonica D. Don) specimens were pressed in the radial direction under six combinations of nominal compressive strain (33% and 50%) and press temperatures (140°C, 170°C, 200°C). Creep tests were conducted at 20°C with three cyclic relative humidity changes between 65% and 95% under 25% of short-breaking stress. The effect of moisture content (MC) change on elastic compliance and mechanosorptive (MS) compliance was investigated. The relation between MS compliance and thickness swelling was studied. The results indicated that total compliance increased over the history of cyclic moisture changes; and its behavior was closely related to the changes in MC and thickness swelling. The total compliance increased during adsorption and decreased during desorption. Elastic compliance increased linearly with MC and was dependent on press temperature and compression. With increasing MC change, MS compliance increased during adsorption and decreased during desorption. The first adsorption led to greater MS compliance than did the subsequent adsorption with the same amount of MC change. In general, the elastic parameterK _E and the MS parameterK _Mincreased with compression and decreased as the press temperature increased. The MS parameterK _M was apparently greater than the elastic parameterK _E. The MS parameterK _M increased with swelling coefficient K_SW of the hot-pressed specimen during adsorption and decreased with an increasing shrinkage coefficientK _SH during desorption.     

Feasibility of supercritical carbon dioxide as a carrier solvent for preservative treatment of wood-based composites

 Supercritical carbon dioxide (SC-CO₂) was tested for its potential as a carrier solvent for preservative treatment of solid wood and wood-based composites. A preliminary trial showed that the treatability of solid wood varied with its original permeability and that the SC-CO₂ treatment was not promising for refractory timber species such a Larix leptolepis Gordon. In contrast, 3-iodo-2-propynyl butylcarbamate (IPBC)/SC-CO₂ treatment resulted in enhanced decay resistance without any detrimental physical or cosmetic damage in all structural-use wood-based composites tested: medium density fiberboard, hardwood plywood, softwood plywood, particleboard, and oriented strand board (OSB). Further trials under various treatment conditions [25°C/7.85 MPa (80 kgf/cm²), 35°C/7.85 MPa, 45°C/7.85 MPa, 35°C/11.77 MPa (120 kgf/cm²), and 45°C/11.77 MPa] indicated that although small changes in the weight and thickness of the treated materials were noted the strength properties were not adversely affected, except for a few cases of softwood plywood and oriented strand board. The results of this study clearly indicated that the treatment condition allowed SC-CO₂ to transport IPBC into wood-based composites, and the optimum treatment condition seemed to vary with the type of wood-based composite. Received: October 24, 2001 / Accepted: February 15, 2002 Part of this work was presented at the 51st Annual Meeting of the Japan Wood Research Society, Tokyo, April 2001; and the 32nd Annual Meeting of the International Research Group on Wood Preservation, Nara, May 2001 Correspondence to:M. Muin     

Piezoelectric effect of cyanoethylated hydroxyethylcellulose

The piezoelectricity of cyanoethylated hydroxyethylcellulose was investigated. Elastic, piezoelectric, and dielectric relaxations were observed at –80° to –60°C and 0° to 20°C at a frequency of 10Hz. The activation energy is about 9–15 kcal/mol in the low temperature region and about 30–45 kcal/mol at room temperature. These relaxations in the low temperature region may be caused by the motion of the cyanoethyl group and those at room temperature mostly by the motions of the main chain. Cyanoethylated hydroxyethylcellulose has a high piezoelectric strain constant (d ₂₅), which is the largest value among the cellulose derivatives and is almost the same as the value for polyvinylidene fluoride. The electromechanical coupling factor for cyanoethylated hydroxyethylcellulose was small.     

Einfluß physikalischer Parameter auf die Bekämpfung des TabakkäfersLasioderma serricorne Fab. (Col.: Anobiidae) mit Kohlenstoffdioxid unter Hochdruck

Zusammenfassung Der TabakkäferLasioderma serricorne schädigt Tabak, pflanzliche Drogen, Gewürze und andere Lebensmittelrohstoffe und verursacht bedeutende wirtschaftliche Verluste bei den betroffenen Industriezweigen.Mit der Entwicklung einer neuartigen Kombinationsbehandlung mit Kohlenstoffdioxid (CO₂) unter Hochdruck von ca. 20 bar durchStahl und Mitarbeiter steht seit 1985 eine Schnellmethode zur Entwesung innerhalb von wenigen Stunden bereit. Alle Entwicklungsstadien von Arthropoden überleben diese Begasung nicht.Eier des Tabakkäfers starben in einer thermostatisierbaren 400 ml Druckkammer nach Behandlung bei 25 °C mit 25 bar, 30 bar, 35 bar bzw. 40 bar CO₂ nach 80, 52, 37 bzw. 20 min ab. Absenkung der Temperatur auf 15 °C bewirkte Verlängerung der letalen Einwirkzeit um ca. 25%. Die Abtötung der Larven erforderte bei gleichen Bedingungen 30, 15, 7 bzw. 3 min mit ähnlicher Tendenz bei Temperaturerniedrigung. Eine Erhöhung der Temperatur auf 35 °C führte zur Verkürzung der letalen Einwirkzeiten um gleichfalls ca. 25%. Bei 20 bar waren 120 min bei 15 °C, 95 min bei 25 °C und nur 20 min bei 35 °C für vollständige Abtötung (LD₉₅) erforderlich.Für adulte Käfer wurden die Versuchsbedingungen auf 15 bar CO₂ erweitert. Bei 25 °C führten 48 min bei 15 bar, 25 min bei 20 bar, 5 min bei 25 bar, 3 min bei 30 bar, 2 min bei 35 bar und 1 min bei 40 bar zum Tode. Abkühlung auf 15 °C erforderte eine Verlängerung der Einwirkzeit bei 15 bar auf 150 min, bei 20 bar auf 40 min, bei 25 bar auf 30 min, bei 30 bar auf 10 min. Aufwärmung auf 35 °C verkürzte die erforderlichen Zeiten um ca. 50%.Die Wirkung der Methode scheint demnach stark temperaturabhängig zu sein. Bei fünfminütiger Behandlung von Tabakkäfern bei 25 °C und 20 bar CO₂ erhöhte eine Verkürzung der Zeit für den Druckaufbau und Druckabbau von 2 auf 1 min die Mortalität von ca. 20% auf 100%! Die Druckabbauzeit spielte dabei eine überwiegende Rolle. Dies beruht wahrscheinlich auf dem Austritt von Gasbläschen und mechanischer Zerstörung von Zellen und Zellorganellen infolge schneller Expansion. Eine Nachsterblichkeit behandelter, überlebender Tiere konnte nicht nachgewiesen werden.

---

Influence of physical parameters on the control of the tobacco beetleLasioderma serricorne Fab. (Coleoptera: Anobiidae) with carbon dioxide under high pressure

The tobacco beetle leeds to severe losses in stored tobacco and tobacco products, drugs, spices and other foodstuffs.Eggs ofLasioderma serricorne died after treatment in a thermostatisized pressure chamber of 100 ml at 20 °C with 25 bar, 30 bar, 35 bar and 40 bar CO₂, respectively, after 80, 52, 37 and 20 min, respectively. Reduction of the temperature to 15 °C required expansion of the lethal treatment time of about 25%. Control of larvae was obtained at equal conditions after 30, 15, 7 and 3 min, respectively, with similar tendency after reduction of the temperature. Increase of the temperature to 35 °C reduced that lethal exposure time for also about 25%. At 20 bar 120 min were necessary at 15 °C, 95 min at 25 °C and 20 min at 35 °C, for complete control (LD₉₅).With adult beetles in addition to the mentioned parameters 15 bar CO₂ at 25 °C required 48 min 20 bar 25 min, 30 bar 3 min, 35 bar 2 min and 40 bar 1 min for complete control. Cooling at 15 °C led to expansion of the lethal time at 15 bar to 150 min, at 20 bar to 40 min, at 25 bar to 30 min and at 30 bar to 10 min, respectively. Heating to 35 °C helped to reduce these times by about 50% at the given conditions.Efficacy of this method seems to be strongly temperature dependent. The absolute effects are greater at pressure of 20 bar than at 30 bar. With 5 min treatment of adult tobacco beetles at 25 °C and 20 bar CO₂ and time to build up the pressure and pressure decay time of 1 min reduced efficacy to 20%. Especially the change of the decay time had strong influence on the mortality achieved. Presumably this effect can be linked to appearance and of gas bubbles and mechanical destruction of cell membranes and organs due to quick expansion.

     

Creep in chipboard

Summary Deflection under 4-point bending of a range of board types was measured for up to six months. Results were obtained under steady-state conditions of stress level (30%, 45%, 60%, 67.5% and 75% of the short term breaking stress), relative humidity (30%, 65% and 90% rh) and temperature (10°C, 20°C and 30°C). These results are presented in terms of relative creep and creep modulus. The relative creep for all board types increased with increasing stress level, increasing relative humidity and increasing temperature. An analysis of variance investigating variations between materials showed significant differences in relative creep. When the relative creep of all materials was compared over all conditions and all stress levels, plywood and waferboard had consistently low relative creep values. High alkaline cured PF chipboard and non-British Standard UF chipboard had consistently high relative creep values. The creep modulus of MUF bonded chipboard decreased with increasing log₁₀ (time) under all conditions. Creep modulus also decreased with increasing stress level.The statistical analysis in this paper was performed by Anne Hasted and Laura New of the Statistical Services Centre, Reading University     

Prey consumption preferences of<Emphasis Type="Italic"> Serangium parcesetosum</Emphasis> Sicard (Col., Coccinelidae) for different prey stages,species and parasitized prey

Serangium parcesetosum Sicard (Col., Coccinellidae) is considered one of the important predators of whiteflies. However, knowledge about its preferences for different prey stages, species and parasitized prey is still lacking in the literature. The present work investigated the preferences of S. parcesetosum for different stages of B. tabaci, different prey species and B. tabaci parasitized by Encarsia formosa Gahan (Hym., Aphelinidae) by prey consumption at different temperatures in the laboratory. Results showed that L₂ and L₄ predatory instars of S. parcesetosum preferred puparia to nymphs and eggs of Bemisia tabaci (Genn.) (Hom., Aleyrodidae). The mean daily prey consumption was 5.1–9.0, 4.5–6.2 and 3.6–4.3 by L₂ and 6.4–9.7, 5.5–8.5 and 2.5–7.5 by L₄ for puparia, nymphs and eggs, respectively. Adult females, however, indicated a significantly greater preference for both puparia and nymphs, consuming a daily mean of 6.4–7.5 puparia and 5.1–6.7 nymphs, but only 3.0–4.7 eggs. At 18 and 30 °C, all S. parcesetosum stages tested significantly preferred B. tabaci and Trialeurodes vaporariorum Westwood (Hom., Aleyrodidae) over the other three prey species offered. At both temperatures, all predatory stages preferred B. tabaci to T. vaporariorum, the L₂ instar at 18 °C, showing significantly more preference for B. tabaci than T. vaporariorum. In contrast, very few individuals were consumed from Aphis gossypii Glover (Hom., Aphididae), Frankliniella occidentalis (Pergande) (Thys., Thripidae) and Tetranychus urticae Koch (Acari, Tetranychidae). At 18 °C, a daily mean of 7.5–8.0, 6.6–9.0 and 6.7–8.1 B. tabaci as well as 5.3–6.4, 5.4–7.8 and 5.6–6.3 T. vaporariorum was consumed by L_2, L₄ and adult females, respectively, while at 30 °C, L₂, L₄ and adult females consumed a mean of 9.3, 8.8–9.7 and 8.3–9.7 B. tabaci/day as well as 8.3–9.0, 7.8–9.1 and 5.5–8.4 T. vaporariorum/day, respectively. S. parcesetosum L₂ and L₄ instars as well as adult females and males at both studied temperatures showed a significant tendency to avoid B. tabaci puparia after 5 days of parasitism by E. formosa and preferred to feed on unparasitized whiteflies. At 18 °C, the mean daily consumption was 8.7 and 0.2 (L₂), 11.1 and 0.6 (L₄), 12.1 and 1.0 () as well as 10.5 and 0.2 (), while at 30 °C the means were 15.9 and 0.5 (L₂), 19.8 and 1.0 (L₄), 18.9 and 1.2 () as well as 17.4 and 0.6 () from unparasitized and parasitized B. tabaci puparia, respectively.This paper is gratefully dedicated to Prof. Dr. W Schwenke on his 83rd birthday, 22 March 2004     

Mechanical properties assessment of Cunninghamia lanceolata plantation wood with three acoustic-based nondestructive methods

The objectives of this study were to establish the method of evaluating wood mechanical properties by acoustic nondestructive testing at standing trees and at logs of a Chinese fir (Cunninghamia lanceolata (Lamb.) Hook.) plantation, and to compare three acoustic nondestructive methods for evaluating the static bending modulus of elasticity (MOE), modulus of rupture (MOR), and compressive strength parallel-to-grain (σ_c) of plantation wood as well. Fifteen Chinese fir plantation trees at 36 years of age were selected. Each tree was cut into four logs, for which three values of dynamic modulus of elasticity, i.e., E _sw, of the north and south face based on stress waves to assume the measuring state of the standing tree, E _fr, longitudinal vibration, and E _us, ultrasonic wave, were measured in the green condition. After log measurements, small specimens were cut and air-dried to 12% moisture content (MC). Static bending tests were then performed to determine the bending MOE and MOR, and compressive tests parallel-to-grain were made to determine σ_c. The bending MOE of small clear specimens was about 7.1% and 15.4% less than E _sw and E _us, respectively, and 11.3% greater than E _fr. The differences between the bending MOE and dynamic MOE of logs as determined by the three acoustic methods were statistically significant (P < 0.001). Good correlation (R = 0.77, 0.57, and 0.45) between E _sw, E _fr, and E _us and static MOE, respectively, were obtained (P < 0.001). It can be concluded that longitudinal vibration may be the most precise and reliable technique to evaluate the mechanical properties of logs among these three acoustic nondestructive methods. Moreover, the results indicate that stress wave technology would be effective to evaluate wood mechanical properties both from logs and from the standing tree.     

Fire-retardant and smoke-suppressant performance of an intumescent waterborne amino-resin fire-retardant coating for wood

An intumescent waterborne amino-resin fire-retardant coating for wood (C) was synthesized and its fire-retardant and smoke-suppressant properties were investigated. The main film-builder of C was urea-formaldehyde resin blended with polyvinyl acetate resin. The intumescent fire-retardant system of C consisted of guanylurea phosphate (GUP), ammonium polyphosphate (APP), pentaerythritol (PER) and melamine (MEL). Specimens of plywood painted, respectively, with a commercial intumescent fire-retardant coating (A), a synthesized coating (C), and the main film-builder of coating C (B), as well as an unpainted plywood (S-JHB), were analyzed by cone calorimetry (CONE). The results show a marked decrease in the heat release rate (HRR) and the total heat release (THR), an increased mass of residual char (Mass), a marked postponement in time to ignition (TTI) and a reduced carbon monoxide production rate (P _CO). The smoke production rate (SPR) and total smoke production (TSP) of the plywood painted with coating C were observed with the CONE test. The overall fire-retardant and smoke-suppressant performance of the synthesized coating C was much better than that of the commercial coating A. The thermo-gravimetric analysis (TGA) results of coating C and its film-builder B indicated that the thermal degradation process of B was slowed down by the addition of the intumescent fire-retardant system; the increase in the amount of charring of coating C was considerable. __________ Translated from Scientia Silvae Sinicae, 2007, 43(12): 117–121 [译自: 林业科学]     

Coarse woody debris decay rates for seven indigenous tree species in the central North Island of New Zealand

The decomposition rate of stem and branch coarse woody debris (CWD, >10 cm in diameter) was assessed in natural forests located in the central North Island of New Zealand. CWD samples had originated from windfalls associated with cyclone Bernie, and had been decaying for approximately 20 years on the forest floor. Species-specific decay rates were estimated from the density of CWD samples relative to the density of live tree samples from the same stands. Decay rates were determined for rimu (Dacrydium cupressinum), matai (Prumnopitys taxifolia), tawa (Beilschmiedia tawa), miro (Prumnopitys ferruginea) and kahikatea (Dacrycarpus dacrydioides) in podocarp forest at Whirinaki, and red (Nothofagus fusca) and silver beech (Nothofagus menziesii) in beech forest at Kaimanawa. The average decay rate for these seven species, expressed as the time taken to lose 50% mass (t_1/2), was 30 years. Larger trees (90 cm diameter at breast height, dbh) decayed more slowly (t_1/2 = 38 years) than smaller trees (30 cm dbh; t_1/2 = 21 years). After adjustment for dbh, P. taxifolia (t_1/2 = 39 years), N. fusca (t_1/2 = 38 years), N. menziesii (t_1/2 = 31 years) and B. tawa (t_1/2 = 26 years) decayed significantly more slowly than D. cupressinum (t_1/2 = 18 years). D. cupressinum decayed more slowly than P. ferruginea (t_1/2 = 16 years) and D. dacrydioides (t_1/2 = 14 years), although these differences were not statistically significant because the CWD sample size was small for the latter two species. An attempt to expand the range of species studied using data from in-ground durability tests was not successful as species decay rankings from these tests were inconsistent with natural forest CWD rankings. Stems heavily colonized by the common decay fungus Ganoderma cf. applanatum decayed more rapidly (t_1/2 = 20 years) than those which were occupied only by other decay fungi (t_1/2 = 40 years). A tree species and dbh-dependent decay constant, λ, was derived for estimating carbon loss from CWD due to fungal decay and insect activity in indigenous forests. Future research will aim to improve these decay equations by investigating the decomposition processes associated with tree species and basidiomycete populations present at other sites in New Zealand.     

Effective accumulated temperature and developmental threshold temperature for Semanotus bifasciatus （Motschulsky） in Beijing

In order to understand the occurrence and development of Semanotus bifasciatus （Motschulsky）, a borer insect of Platycladus orientalis in parts of northern and eastern China and to improve its prediction, the developmental threshold temperature （C1） and effective accumulated temperature （K） of S. bifasciatus were determined under conditions of constant and variable temperatures. The results show that under constant temperatures the value of C1 has a range of 8.90±1.77℃and the value of K lies between 95.19±13.14 degree-day for eggs; the values for larvae are C1= 13.26±3.06℃ and the number of degree-day is K 2,885.07±187.87 degree-day; for pupae the ranges are C1 = 8.93±2.49℃ and K= 131.20±25.63 degree-day. Under the condition of ambient temperatures, the values for eggs are C1= 17.33±1.24℃ and K= 70.79±8.99 degree-day. It is suggested that S. bifasciatus adults over-winter in a state of dormancy, not at a diapause. Warm winter may accelerate the life cycle ofS. bifasciatus. Equations can be used to predict an early occurrence ofS. bifasciatus.     

Effects of temperature on reproductive capacity and longevity of Trissolcus simoni, an egg parasitoid of Eurygaster integriceps

In order to understand the effects of temperature on Trissolcus simoni, some parameters of the life tables of adult parasitoids were investigated under laboratory conditions. The following parameters were measured (the values in parentheses were obtained at 20, 26, and 32 °C temperatures, respectively): net reproductive rate (R_o=37.785, 40.301, and 58.299), intrinsic rate of population increase (r_m=0.111, 0.221, and 0.325), generation time (T=32.77, 16.60, and 12.49 days), doubling time (DT=6.245, 3.136, and 2.133), and finite rate of increase (=1.117, 1.247, and 1.385). Fecundity increased with increasing temperature. The values for total number of eggs deposited per female were 50.1, 64.1, and 68.1, and average female longevity was 24.2, 13.8, and 11.1 days at 20, 26, and 32°C, respectively. Temperature had a significant effect on longevity and oviposition and post-oviposition periods. The results of the study are discussed and compared with life-table parameters of other scelionids.     

Thermal properties of interior decorating material and the sensation of cold/warm by contact II: the relations among heat flux, temperature change of material, and sensation of cold/warm by contact

The main purpose of this study was to investigate the changes in heat flux and temperature after the subject's palm was in contact with interior decorating materials. The relations among heat flux, temperature, and sensation of cold/warm during contact were studied. Ten men and ten women were selected and introduced to 21 materials for the contact test. They were in contact with the specimens for 30min without seeing them in a climate-controlled room at 25°±1°C and 65% RH. Changes in the heat flux and temperature of the specimens were determined by a heat flux meter. A sensory evaluation test was applied to evaluate the cold-warm contact. Results indicated that the heat flux and temperature increased with increasing time after the subject's palm was in contact with the specimens. The heat flux (Q ₃₀) and temperature (T ₃₀) 30min after the subject's palm contacted the specimens were greater for male subjects than for female subjects. A positive linear regression equation existed between the values for Q₃₀ andT ₃₀, whereas a negative linear regression formula existed the sensation of cold-warm by contact (5) and the values of ln(Q ₁·). Therefore, the sensation of cold/warm by contact could be estimated simply by using the thermal physical properties of the interior decorating materials.Part of this report was presented at the International Conference on Effective Utilization of Plantation Timber, Chi-Tou, Taiwan, ROC, May 1999     

Manufacture of plywood bonded with kenaf core powder

Kenaf (Hibiscus cannabinus L.) core powder was used as a binder to manufacture three-ply plywoods of sugi (Cryptomeria japonica D. Don) by conventional hot pressing under various manufacturing conditions: hot-pressing conditions (pressure, temperature, and time) and powder conditions (grain size, spread volume, and moisture content). The adhesive shear strength and wood failure of plywoods were measured in accordance with the Japanese Agricultural Standard (JAS) for plywood. The result showed that fine kenaf core powder played a role as an effective binder when plywoods were pressed at high pressure, which caused extreme compression of veneer cells. In addition, the adhesive shear strength of plywoods in dry conditions was high regardless of pressing temperature and time, but it was sensitive to pressing temperature and time in wet conditions. The highest adhesive shear strength was obtained from plywoods manufactured with kenaf core powder (grain size 10 μm, spread volume 200 g/m², moisture content 8.6%) under hot-pressing conditions (pressure 5.0 MPa using distance bars 4 mm thick, temperature 200°C, time 20–30 min). However, the plywood could not meet the requirement for the second grade of plywood by JAS because of its low water-resistance properties. Part of this article was presented at the 58th Annual Meeting of the Japan Wood Research Society, Tsukuba, March 2008, and the 10th World Conference on Timber Engineering, Miyazaki, June 2008