Effect of fire-retardant treatment on plywood pH and the relationship of pH to strength properties

Summary This paper investigates the relationship between wood pH and the strength properties of fire-retardant-treated (FRT) plywood, as it is affected by fire-retardant (FR) formulations, processing variables, and extended high temperature exposure conditions. The objectives of this study were to (1) identify the effect of post-treatment kiln-drying temperature, followed by high temperature exposure, on wood pH; (2) identify the effect of various mixtures of FR components, followed by high temperature exposure, on wood pH; (3) determine if treatment effects on strength and pH are affected by plywood thickness; and (4) quantify the relationship between changes in wood pH and strength loss and whether pH can be used as a predictor of strength loss. Results indicate that the differences in pH resulting from the initial redry temperature became insignificant after extended periods of high temperature exposure. All FR treatments studied caused large, rapid decreases in pH, with the most rapid decreases occurring with formulations containing phosphoric acid. Additions of borate compounds, especially disodium octaborate tetrahydrate (Timbor), produced a measurable buffering effect that slowed or lessened the decreases in pH. No differences in the effect of FRT on the wood pH-strength relationship were noted between the two plywood thicknesses evaluated. A strong relationship was noted between changes in pH of the plywood and reductions in strength and energy-related properties. These findings suggest that the pH of FRT plywood is a good indicator of its current condition and may have potential as a predictor of future strength loss as the plywood is subjected to elevated in-service temperatures. Received 8 January 1997     

Natural autoxidation of longifolene and anti-termite activities of the products

Here, we investigated the reaction mechanism of longifolene autoxidation and the bioactivities of its products. A longifolene sample was autoxidized at 120 °C or room temperature, and the products were analyzed by gas chromatography. Longicamphenylone, norlongilactone, isolongifolic acid, longifolic acid, and longifolene–hydroxy ketone were detected as the products in the autoxidation at 120 °C. During the reaction, longifolene was converted into the other autoxidation products via the formation of longifolene oxide as an intermediate. Anti-termite activities of the longifolene and its autoxidation products were examined against a Japanese subterranean termite (Reticulitermes speratus Kolbe) by paper disk methods in Petri dishes. Longifolene and the autoxidation products exhibited anti-R. speratus activities, and all the autoxidation products had stronger termiticidal and antifeedant activities than longifolene.     

不同光强下pH对伊乐藻光合机能的影响

不同光照条件下,研究pH变化对伊乐藻光合机能的影响。实验在水生植物培养室中进行,水培箱水深0．5m,植物在不同光照条件和pH条件下培养40d,实验发现pH对植物的影响常常和光照的强弱有一定关联,在pH高于9．0条件下,伊乐藻的叶绿素含量、PSII活力、Rubisco活力和生物量下降,但在弱光条件下（60lx）时,高pH对植物的影响程度加强。长期的高pH水平和低光照协同作用是湖泊富营养化过程中沉水植物种群退化的重要机制之一。     

土壤质地和pH值对节肢动物多度的影响

为了探讨土壤质地和pH值对节肢动物多度的影响,于2008年8月对车八岭自然保护区进行了野外调查和采样,共捕获土壤节肢动物600头,隶属于6亚纲12目,其中以甲螨亚目的数量最多。结果表明:土壤节肢动物主要分布在凋落物层和表土层,优势类群基本为甲螨亚目和中气门亚目;土壤质地对土壤节肢动物多度有明显的影响,即在同一质地条件下,土壤节肢动物多度与土壤有机质含量之间有紧密的联系,两者呈多项式相关;土壤节肢动物多度与土壤全氮含量关系则受pH值的影响,当pH值4.2时,两者呈线性相关,而当pH值4.2时,两者呈多项式相关。     

Effect of high temperature heat treatment on pH value of Masson Pine wood

Heat-treated wood has good dimensional stability, corrosion resistance and visual quality, but it is prone to mold, which limits its application. Based on the pH value of heat-treated wood, this study examines the factors affecting the pathogenesis causing heat-treated wood mold. Normally, the pH value of the heat-treated wood is between 4.38 and 5.10, which is suitable for the growth of mold. However, the pH of the heat-treated copper-containing material is between 6.63 and 7.12, which deviates the treated wood from the comfortable growth conditions for the mold, thereby reducing the occurrence of mold.     

Effect of high temperature heat treatment on pH value of Masson Pine wood

Heat-treated wood has good dimensional stability,corrosion resistance and visual quality,but it is prone to mold,which limits its application.Based on the pH value of heat-treated wood,this study examines the factors affecting the pathogenesis causing heat-treated wood mold.Normally,the pH value of the heat-treated wood is between 4.38 and 5.10,which is suitable for the growth of mold.However,the pH of the heat-treated copper-containing material is between 6.63 and 7.12,which deviates the treated wood from the comfortable growth conditions for the mold,thereby reducing the occurrence of mold.     

林分组成对林下土壤pH及有机质含量变化的影响

以阜新地区油松+樟子松混交林和油松纯林的林下土壤为研究对象,通过研究不同林分组成下对土壤pH和有机质含量指标的变化,来探讨当地混交林林地土壤的特点。试验结果表明:土壤的pH随着土层的深度的增加而增加,但是还呈酸性;混交林各层土壤的pH显著高于纯林,对于土壤酸化有改善作用;土壤有机质含量变化是随着土层的深度的增加而降低,混交林各层土壤的有机质含量显著高于纯林,混交林有机质含量的提高能改善林地土壤质量。     

不同pH值对兴安杜鹃及迎红杜鹃生理特性的影响

在不同pH的栽培基质上,对培养20天后的兴安杜鹃、迎红杜鹃苗木的根系活力、叶绿素含量、脯氨酸含量和可溶性糖含量进行了测量,其结果表明,pH水平对兴安杜鹃、迎红杜鹃苗木各生理指标均有显著影响,当pH值为5．5时,苗木的生长状态最佳。     

Effect of NaCl and high pH on seedling growth of 15 Eucalyptus camaldulensis Dehnh. provenances

Eucalyptus camaldulensis Dehnh. is a moderately salt-tolerant Australian tree species widely used in farm forestry, often in salt-affected landscapes. In a glasshouse experiment, E. camaldulensis seedlings from 15 wide-ranging Australian seed sources (provenances), were cultured in sand-filled pots and treated for 57 days with control (no added NaCl in tap water, neutral pH), saline (150 mol m^–3 NaCl, stepped high pH (pH 7.6 to 9.5) and combined NaCl and high pH solutions. Significant differences were found among provenances in height and shoot dry weight. Differences in provenance response to treatment were found for dry weight but not for height. Reductions in shoot dry weight due to NaCl and high pH ranged from 42.9% to 82.0% and 4.3% to 51.7% respectively. Provenances from Lake Hindmarsh-SE (Victoria) and Lake Albacutya-N (Victoria) had relatively high tolerance to both stresses whereas those from Lake Albacutya-S (Victoria), Lowan Valley (Victoria), Silverton (New South Wales) and Katherine (Northern Territory) had low tolerance to both stresses. Provenances from De Grey River and Fitzroy River (Western Australia) were most tolerant of high pH. The performance of these provenances in this experiment generally accorded well with that in saline field environments.     

不同N素形态对落叶松苗木根/土界面pH值及养分有效性的影响

尽管根/土界面一般是指根围数毫米范围内的微域土区,但该微区中物理、化学和生物学状况直接影响着土壤中水分、养分的向根迁移、转化和有效性,影响着植物根的吸收和生理活性(刘芷宇等,1997),因此对于该微区的研究在理论与实践上都具有极为重要的意义.     

土壤pH对蓝莓生长及光合作用的影响

以南高丛蓝莓薄雾(Misty)为试验材料,用H2SO4、Al2(SO4)3和NaOH溶液浇淋(处理)盆栽蓝莓的土壤,以调节土壤pH值,测定蓝莓叶片的叶绿素含量、光合作用及生长指标。结果表明:随着土壤pH值降低,蓝莓叶片叶绿素含量,最大净光合速率(Pmax)、表观量子效率(AQY)、光饱和点(LSP)和光补偿点(LCP)均升高。其中以pH 4.5的处理蓝莓叶绿素含量最高,植株生长势最好;pH 8.5的处理光合强度与生长势均最低。因此,南高丛薄雾蓝莓适合栽培的酸性土壤p H值范围为4.5~5.5,而碱性土壤则抑制其生长。     

培养液pH值对喜树幼苗生长与SOD活性、脯氨酸和叶绿素含量的影响

本研究确定适宜喜树幼苗生长的pH值，结果表明，幼苗根际pH值对叶片内不同，叶片叶绿素，游离脯氨酸含量与SOD活性均存在着一定的差异，当培养液的pH为5．5－6．5时叶片中叶绿素含量最高，SOD活性最强，游离脯氨酸含量最低，初步认为5．5－6．5是喜树幼苗适宜的pH环境。     

Effect of pH,temperature and light on the pathogenicity of Cylindrocarpon destructans to pine seedlings in associative cultures with bacteria and actinomycetes1

The effect of pH, temperature and light on pathogenicity of two isolates of Cylindrocarpon destructans was studied. Both isolates were pathogenic to fir and pine seedlings. The degree of aggressiveness was affected by pH, temperature, light intensity and also by accompanying bacteria and actinomycetes.     

Study on Impacts of pH Value on Paulownia Wood Color

INTRODUCTIONPaulownia is one of important species with fastgrowth and high yield oriented to industry uses inChina, paulownia wood is widely used in furniture-making, decorating materials, musical instrumentsmanufacture (Jiang Jianping 1990), etc. Brown orblack stain often appears on the surface of paulowniawood during processing and using. Discolorationseriously affects paulownia utilization, and it cancause huge loss due to low grade and price causedby stain (Cheng Junqing 1983a, 1983b…     

Modeling the kinetics of moisture adsorption by wood

Summary Modeling of the kinetic of moisture adsorption by wood has been studied by using cubic samples. The model is based on an explicit numerical method with finite differences. Experiments have been carried out either for determining the data necessary for calculations (diffusivity, amount adsorbed at equilibrium) and for testing the validity of the model. Two different experiments have been done in case of the longitudinal adsorption: the one by increasing the relative humidity of the atmosphere following a discontinuous step by step process. The other by determining the kinetic adsorption of moisture by samples previously equilibrated under the same conditions when they are contacted with atmosphere at various R. H. Good correlations are obtained between calculated values and experiments in both cases. Although the actual paper is concerned with constant diffusivity, the model is capable to use concentration-dependent diffusivities.This work has been done with the help and support of the French C.T.B. (Wood Technical Center), 10 Av. St.-Mandé, Paris     

HTST hydrolysis of wood: Modelling of the kinetics and projections on reactor configuration

Summary We present experimental data on hydrolysis of wood in high temperature short residence time (HTST) and low acid concentration conditions. Effects of temperature, acid concentration, particle size and liquid/solid ratio are discussed. A kinetic model is proposed which accounts for effects of temperature and acid concentration. This kinetic model is used to predict performance of a twin-screw extruder as a hydrolyser which consists of ideal mixed flow or plug flow reactor units in series.Symbols A Acid concentration in liquid phase - A Acid concentration in solid phase - A₀ Initial mass of sulphuric acid, g - C Cellulose content of solid phase, % - d Diameter of wood particles, m - E₁ Activation energy of cellulose hydrolysis, cal. mol^-1 - E₂ Activation energy of glucose degradation, cal. mol^-1 - F Objective function, refers to Eq. (5) - G Glucose yield - G_e Glucose yield at equilibrium - G_{i, exp} Experimental glucose yield (Eq. (5)) - G_{i, th} Calculated glucose yield (Eq. (5)) - G_max Maximum glucose yield - k^* Parameter defined by Eq. (9) - k₁ Rate constant of cellulose hydrolysis, s^-1 - k₂ Rate constant of glucose degradation, s^-1 - k ₁ ^* Apparent rate constant of cellulose hydrolysis, s^-1 - k ₂ ^* Apparent rate constant of glucose degradation, s^-1 - k₁₀ Pre-exponential factor of constant k₁, s^-1 - k₂₀ Pre-exponential factor of constant k₂, s^-1 - K Parameter defined in Table 3 - m Constant - m_g Mass of glucose produced, g - M₀ Initial mass of wood, g - M Mass of saturated steam delivered, g - M Mass of saturated steam delivered after 120 s of reaction time, g - m₀ Initial mass of water, g - n Constant - N Number of reactor units - q_i Volume flow rate in reactor units, m³ · s^-1 - r_g Conversion rate of glucose, s^-1 - R Ideal gas constant, 1.987 cal · mol^-1 K^-1 - t Reaction time, s - T Temperature, K - V_i Volume of reactor units, m³ - W Water content of wood sample, % - X, X Parameters defined in Table 3 - Y, Z Parameters defined in Table 3 - Constant defined in Eq. (4), s^-1 - v Number of experimental points (Eq. (5)) - _i Residence time in plug flow unit, s - _i Residence time in mixed flow unit, s     

不同pH对扁桃胶水解物晶体特性的影响

利用RINT2000 vertical goniometer型X-衍射仪测定不同pH条件下扁桃胶水解物的结晶度,研究不同pH条件对扁桃胶晶体特性的影响规律,并用电子显微镜观察水解物的微晶结构。结果表明:1)pH的改变不仅能够使非晶体的扁桃胶表现出晶体特性,而且对晶相也有极显著的影响,在pH3～1,晶体结构与多糖的微纤维化有关,在pH11～13,晶体与多糖的结构有关;2)以pH7为中心坐标,随着pH的不断降低,扁桃胶的结晶度变化符合方程y=10.94201e-(x-2.23006)2/1.872403(R2=0.85175);随着pH的不断增加,扁桃胶的结晶度变化规律符合方程y=-8.83822+1.38118x(R2=0.89675)。     

冬枣果实三种主要病原细菌对温度和pH值的耐受力研究

摘要：研究了冬枣采后烂果上分离的3种主要病原细菌假单胞杆菌(Pesudomonas sp．)、黄单胞杆菌(Xanthomonas sp．)和欧氏杆菌(Erwinia sp．)对温度和pH值的耐受力。结果表明,假单胞杆菌的低温和高温耐受力分别为0℃和57．5℃;黄单胞杆菌的低温和高温耐受力分别为-2℃和55℃;欧氏杆菌的低温和高温耐受力分别为0℃和57．5℃。3种病原细菌对偏碱性环境耐受力较强,假单胞杆菌在pH值10时才停止生长,黄单胞杆菌和欧氏杆菌在pH值12时仍能生长;在酸性范围内,当pH值2～4时生长均受到抑制。pH、温度和时间复合处理的试验中,在pH值3～4,处理时间6～10min,假单胞杆菌处理温度在45℃,黄单胞杆菌在55℃,欧氏杆菌在50℃时,生长受到显著抑制.     

染色木材pH值与缓冲容量的比较分析

分别用酸性染料与活性染料,对大青杨和桦木单板进行直接染色和NaOH溶液预处理后染色,测量2种染色单板的pH值和缓冲容量,并与未染色单板进行对比.结果表明,NaOH溶液预处理、酸性染料、活性染料的染色对2种单板的pH值及缓冲容量的影响规律一致;染色可小幅度增加木材pH值,显著降低酸缓冲容量;预处理则可较大幅度增加pH值,并一定程度上增加酸缓冲容量;大青杨单板经2种工艺染色后,其酸缓冲容量均有明显下降;桦木单板直接染色酸缓冲容量减小,而预处理后染色则酸缓冲容量增大.