铯-137γ射线辐射对郁金香鳞茎的诱变效应

采用铯-137γ射线对郁金香Tulipagesneriana鳞茎进行辐射,研究不同辐射剂量对郁金香花芽分化、出苗率、蕾期及花期性状的影响。结果表明,采用5~30 Gy辐射处理,不同品种对铯-137γ射线辐射的敏感性不同,辐射剂量越大辐射效应越显著。随着辐射剂量的增大,鳞茎中心芽的生长受到抑制作用越明显、花芽分化进度越迟缓、花结构更不完整、郁金香出苗率越低。蕾期主要变异有植株矮小、长势缓慢、叶片开裂或畸形。花期调查表明:和对照相比,5 Gy处理的花瓣边缘出现不同程度的裂刻;10 Gy处理的郁金香花葶不抽出、雄蕊和雌蕊畸形、部分花瓣变异或缺失。结论:郁金香的铯-137γ射线半致死辐射剂量在5~10 Gy,5 Gy是筛选郁金香花部变异的合适剂量。     

氧化反应对热处理固定杉木压缩木材的影响(英文)

该研究的目的是明确氧化反应对热处理固定杉木压缩木材的影响 .首先 ,饱水状态的杉木试件在热压机中被径向压缩约 50 % ,然后压缩试件被分别放在一个普通烘箱 (有氧热处理 ,空气的压力为大气压 )和一个真空干燥箱中 (真空热处理 ,空气压力很低 ,约 0 .0 75MPa)进行热处理 ,两种热处理都设置了 5种温度包括 140 ,160 ,180 ,2 0 0 ,2 2 0℃以及不同的时间 .同时进行热处理的还有一些绝干的对照试件 ,用来测定不同热处理过程中的重量损失率 (WL)和抗收缩率 (ASE) .研究结果如下 :( 1)热处理过程中氧气的存在大大提高了热处理的效率 ,在 2 2 0℃时有氧热处理约 2 .5h后 ,压缩木材的RS(回复率 )达到 0 ;但在真空热处理时 ,在 2 2 0℃时加热约 30h后 ,压缩木材的回复才能基本被固定 .( 2 )氧化并不是压缩变定的固定、木材重量的损失或尺寸稳定性提高的必不可少的条件 ,氧气的存在几乎对RS和WL以及ASE和WL间的关系没有影响 ,但对RS和ASE间的关系有一些影响 .( 3)T T平面中的RS等值线 ,Δt一定回复率和温度下两种热处理所需时间的差值 )和温度间的关系 ,以及由于氧化反应而引起的热处理效率增加的系数 η清楚地反映了氧化反应对热处理固定杉木压缩木材的效率的影响     

不同剂量~(60)Co-γ射线对凤丹种子生根、出苗及幼苗生长的影响

以凤丹(油用牡丹)的干种子、湿沙层积的湿种子为辐射诱变材料,通过不同剂量60Co-γ射线照射处理,研究对种子生根、幼苗生长及幼苗变异情况的影响。结果表明:凤丹干、湿种子的生根率、主根长度≥4 cm种子的百分率、须根的比率均表现为低剂量促进、高剂量抑制的趋势。低剂量辐射处理干、湿种子,均表现为初萌期提前,出苗指数和出苗率提高;随着剂量增加,初萌期延迟,出苗指数和出苗率降低。根据出苗率计算出凤丹干、湿种子的半致死辐射剂量分别为18.94 Gy和9.51 Gy。干种子中低辐射剂量(10 Gy)处理的苗高与对照无显著差异;当辐射剂量超过20 Gy时,苗高随辐射剂量的增大而降低。各处理幼苗的茎粗与对照均无显著差异。辐射对湿种子幼苗高度的影响与干种子相似,但湿种子耐辐射能力稍差,辐射超过6 Gy,苗高即显著低于对照;而较高辐射处理(10—20Gy)的湿种子幼苗茎粗显著低于对照。干、湿种子的幼苗变异率均表现为随辐射剂量加大逐渐增大的趋势。60Co-γ射线对凤丹幼苗的诱变效应主要表现为小叶退化和叶色变化,且随辐射剂量增大,幼苗也会出现叶片畸形、叶尖枯萎、茎徒长等畸变。     

~(60)Co-γ射线对鸡爪槭种子发芽与出苗的影响

为探讨~(60)Co-γ射线对鸡爪槭种子发芽与出苗的影响,本研究以三株鸡爪槭种子为试材,采用不同辐射剂量γ射线辐射对鸡爪槭种子进行γ射线辐射,结果表明:发芽率随着辐射剂量的增加而降低,50 Gy以下的低剂量发芽率降低较缓,大于50 Gy的高剂量成活率急剧下降,在200 Gy以上发芽率几近零;随着辐射剂量的增加出苗率呈现先增加后降低的趋势,50Gy具有最高出苗率(52.00%);试验计算所得鸡爪槭种子的半致死剂量在77.93 Gy-89.58 Gy之间,平均为85.25 Gy,初步认为最适辐射剂量为85 Gy,对于鸡爪槭种子辐射育种具有一定的参考价值。     

热处理和蒸汽处理对压缩杉木性能的影响北大核心

以压缩杉木为研究对象,采用热处理和蒸汽处理两种方法,在不同温度条件下(160、180℃和200℃)对其进行压缩变形固定处理,分析不同处理工艺条件对压缩杉木回复率、残余应力和力学性能的影响,并探究压缩杉木变形固定机理。结果表明:热处理和蒸汽处理都可以降低压缩杉木的回复率和残余应力。随着处理温度的升高、处理时间的延长,压缩杉木的水煮回复率和吸湿回复率均减小。与热处理相比,各温度条件下蒸汽处理的压缩杉木水煮回复率和吸湿回复率均较小。随着处理温度的升高和处理时间的延长,热处理和蒸汽处理均可减少残余应力。在相同处理温度和处理时间条件下,蒸汽处理对压缩杉木的残余应力有更好的消除效果。热处理和蒸汽处理对压缩杉木力学性能都有一定的削弱作用,特别当处理温度达到200℃时,力学性能下降幅度较大。热处理和蒸汽处理改变了压缩杉木中C元素和O元素含量,O/C值分别降低了5.88%和7.84%;不改变压缩杉木纤维素结晶区的晶胞构造,但相对结晶度分别减小了5%和3%。综合考量,对压缩杉木采用蒸汽处理(180℃)进行变形固定是较好的选择。     

~(60)Co-γ辐射对丛生福禄考植株形态的影响

采用不同剂量(0～100 Gy) ~(60)Co-γ射线,辐射丛生福禄考带芽茎段的研究结果表明:30～60 Gy的辐射利于丛生福禄考的形态发生变异,宜适辐射诱变剂量为60 Gy;80～100 Gy高剂量的辐射抑制植株生长,且随着辐射剂量的加大,抑制作用增加。     

黄山栾树种子~(60)Co-γ射线辐射试验初报

用不同剂量(100,200,400,600和800 Gy)的60Co-γ射线辐射6个黄山栾树优株的种子,对辐射后种子的发芽和幼苗生长情况进行了观测,结果表明:6个黄山栾树优株的种子辐射半致死剂量大小依次为"优5"(518 Gy)、"优2"(503 Gy)、"优3"(496 Gy)、"优6"(485 Gy)、"优1"(478 Gy)、"优4"(458 Gy)。60Co-γ辐射可引起幼苗表型改变,随着辐射剂量的增加,幼叶及茎形状发生一些变异。     

~(60)Co-γ射线对2种园林植物种子萌发和幼苗生理特性的影响

为掌握~(60)Co-γ辐射对园林植物—大花秋葵和锦葵的辐射诱变效果,采用不同剂量~(60)Co-γ射线分别对大花秋葵和锦葵种子进行辐射处理,并用穴盘播种,测定2种园林植物种子的发芽率、发芽势、可溶性糖、可溶性蛋白及丙二醛(MDA)含量。结果表明,当辐射剂量低于60Gy时,辐射处理能促进大花秋葵和锦葵种子萌发;叶片中可溶性糖、可溶性蛋白和MDA等生理指标均有不同程度的提高,从而增强了植物的抗逆性。当辐射剂量大于200Gy时,2种植株幼苗死亡现象十分严重,理化性质也发生逆向改变,说明高剂量辐射诱变是逆向的,不利于种子萌发和生长。根据半致死剂量计算公式可以得出大花秋葵的辐射半致死剂量为388Gy;锦葵的辐射半致死剂量为144.14Gy。     

60Coγ射线对舞毒蛾虫卵死亡率的影响

用60Co不同剂量的γ射线辐照处理舞毒蛾虫卵,观察虫卵死亡率的变化情况,并对其致死剂量进行了研究,目的是为物理辐照灭虫的研究和实际应用提供理论依据.实验证明:用γ射线辐照处理的虫卵的死亡率比对照组低,辐照剂量超过200Gy时,γ射线杀伤作用明显、死亡率变化急剧上升,且随着γ射线辐照剂量增大,死亡率有明显上升的趋势.     

^60Coγ射线辐照对马尾松毛虫繁殖力的影响

人工饲养的马尾松毛虫老熟蛹经10~80 Gy剂量的60Coγ射线辐射后,调查辐射对松毛虫繁殖力的影响。结果表明老熟蛹辐照对成虫寿命和产卵量影响不明显,辐照后的雌性成虫与对照雄虫交尾所产卵的孵化率随着辐照剂量的加大而明显降低,经80 Gy以下剂量辐照的雄性成虫与对照雌虫交尾所产卵的孵化率随着辐照剂量的加大没有明显的下降。人工饲养的马尾松毛虫老熟蛹经80 Gy以上剂量辐照对雌雄成虫的繁殖力都有显著影响,对雌性的繁殖力影响大于雄性。     

Studies on pre-treatment by compression for wood impregnation I: effects of compression ratio,compression direction,compression speed and compression-unloading place on the liquid impregnation of wood

To improve the impregnation of wood, the pre-treatment by compression was systematically studied in terms of effects of compression ratio, compression direction, compression speed and compression-unloading place on the liquid impregnation in poplar and Chinese fir. The results showed: the impregnation increased 0.0065 or 0.0074 g/cm³ for every 1% increase of compression ratio when the compression ratio was lower or equal to 50 and 40% for poplar and Chinese fir, respectively; it continued to increase afterwards while the variation was quite big. There existed a significant difference of the impregnation of wood compressed at different directions in Chinese fir, but not in poplar. There existed a significant difference of the impregnation of wood compressed at different speed in both species. The impregnation of wood is likely to be in favor of radial compression in terms of the amount of impregnation. 5 and 10 mm/min were recommended as a compromise of impregnation and pre-treatment efficiency. The impregnation of wood that the compression unloaded in water was about 18.2 (poplar) and 9.2% (Chinese fir) higher in amount and was much quicker in speed than that the compression unloaded in air, and the difference between them was significant, suggesting that compression unloaded in water is significant to improve the impregnation.     

压前含水率对杉木间伐材压缩木性能的影响

通过对杉木间伐材压缩密化的水分和物理力学性能进行分析,并观察木材微观结构的变化,可得出以下结果：1)压缩木各方向的水分分布不均匀,容易翘曲变形；2)水分对压缩木的物理力学性能有影响,压前含水率50％左右,压缩木硬度、抗弯弹性模量和抗弯强度最大,但冲击韧性随着压前含水率的增加呈下降趋势。从微观结构的观察可知,杉木间伐材压缩木的细胞只是被挤压,细胞腔变小而细胞壁未受到破坏。为了降低压后含水率,使水分分布均匀,可以采取两种办法：一是使初始含水率尽可能低,二是热压时间尽可能长。     

Effect of gamma-irradiated entomopathogenic nematodeSteinernema carpocapsae (Fil.) on the larvae of the potato tuber moth,Phthorimaea operculella (Zell.)

The effect of gamma irradiation on the pathogenicity of the entomopathogenic nematodeSteinernema carposapsae was studied by infecting the larvae of the potato tuber moth,Phthorimaea operculella. Full grown larvae of the host were gamma-irradiated with different doses ranged from 2.5 to 160 Gray (Gy) and subsequently infected with either unirradiated or irradiated infective juveniles (IJs) ofS. carpocapsae using the same doses. For comparison, two groups of unirradiated and irradiated host larvae were left without nematode infection. Another group of larval host was also infected with nematodes either unexposed or exposed to the previous doses.The results revealed that there was a rapid mortality in the irradiated host infected with either unexposed nematodes or nematodes irradiated with different doses similar to the mortality in the nematode treatment alone. On the other hand, the pathogenicity of the nematodes was affected as a result of gamma irradiation with high doses, i. e. irradiation of nematodes delayed their efficiencyvis à vis the unirradiated host. However, lower doses of gamma irradiation exhibited worthily stimulating effect on the pathogenic nematodes, one week post irradiation, as it reduced by half the period of time required for killing all irradiated host larvae with regard to nematode treatment alone. Furthermore, nematode treatment whether applied alone or combined with gamma irradiation appears very promising as compared with single irradiation treatment of the host.With 3 tables     

PF树脂浸渍速生杉木的性能研究

速生杉木通过浸渍PF树脂并压缩改性后,力学性能得到大幅度提高,且随着树脂浓度和压缩率的增加而提高。增重率与真空度、浸渍压力、时间有关,并随着其增加而增大;抗胀(缩)率和阻湿率与树脂的浓度有关,当树脂浓度从0上升到10%时,ASE和MEE的值变化较大,当树脂浓度超过10%后趋于平缓;在树脂浓度相同的情况下,较大压缩的恢复率也相应较大,当树脂浓度低于10%时,随着浓度增加,恢复率急剧下降,浓度达到15%以上时,恢复率几乎没有变化。     

Creep of Chinese fir wood treated by different reagents

In order to investigate the effect of different reagents on changes of the crystalline region and amorphous region (Matrix) in wood cell walls, the creep behavior of Chinese fir (Cunninghamia lanceolata) wood treated with dimethyl sulfoxide(DMSO) and diethyl amine, sulfur dioxide and dimethyl sulfoxide mixture (1)EA-SO2-DMSO), and the untreated wood at oven-dried, air-dry and water-saturated states during adsorption and desorption processes were all examined in air or in water. The measurements were carded out at ambient temperature and atmospheric pressure. The load is constant with 62 g or 0.607 6 N. The results obtained were as follows: 1) The instantaneous compliance J0 and the creep compliance J of specimens decrystallized with DEA-SO2-DMSO solution were bigger than those of DMSO swollen wood, and the latter was still much bigger than those of untreated wood. 2) For untreated wood, J0 and J increased with equilibrium moisture content (EMC) of wood, but there was not apparent correlation between wood EMC and the relative compliance. 3) Specimens treated with DMSO and DEA-SO2-DMSO mixture were recrystallized after immersion in water, and the degree ofrecrystallization of the former was larger. 4) For oven-dried specimens, the creep compliances in water were bigger than those in air. But for fiber-saturated and water-saturated specimens they were nearly equivalent to each other.     

Studies on pre-treatment by compression for wood drying III: the reduction of moisture content,the recovery rate,and mechanical properties of wood compressed at different moisture content conditions

As a follow-up report, the pre-treatment by compression for wood drying was systematically studied in terms of the reduction of moisture content (MC), the recovery rate (RR), and mechanical properties of wood compressed at different MC conditions. The results showed that MC after compression on water-saturated wood determined the critical value of MC before compression which were about 84 and 105% at a compression ratio of 60 and 40% for Poplar and Chinese fir, respectively. Beyond the critical value, MC after compression remained constantly at about 84% and decreased slightly from 105% for Poplar and Chinese fir, respectively. The MC reduction decreased with the decrease of MC before compression. The MC reduction was rather effective when the MC before compression was higher than the critical value and was recommended to pre-treat for the effectiveness of MC reduction. In addition, after the recovery, the wood volume and mechanical properties were well retained for the wood compressed at all MC conditions which were above fiber saturation point (FSP) before and after compression. Therefore, the pre-treatment by compression is viable in terms of the RR and mechanical properties at rather broad MC conditions above FSP. Moreover, the compression force needed for treatment was almost same at these MC conditions.     

Effects of gamma radiation on life stages of the Mediterranean flour moth, Ephestia kuehniella Zeller (Lepidoptera: Pyralidae)

We report the results of experiments conducted with Ephestia kuehniella Zeller to determine the effects of gamma radiation on life stages. Eggs, larvae, pupae and adults were irradiated with increasing doses of gamma radiation (seven dose levels between 50 and 400 Gy for eggs and larvae, six dose levels between 50 and 350 Gy for pupae and four dose levels between 250 and 550 Gy for adults). All the experiments were conducted in a growth chamber maintained at 27 ± 1°C, 65 ± 5% r.h., and alternating 14 h light:10 h dark cycles. The number of adults that developed from irradiated eggs and larvae was lower than the untreated control. Doses of 200 Gy and above prevented adult emergence from irradiated eggs. Although a dose of 200 Gy was enough to prevent adult emergence from young larvae, 250 Gy should be used to prevent adult emergence completely from last instar larvae. Delayed developmental periods were observed for the treated eggs and larvae. Fecundity and egg hatchability were decreased depending on the doses applied. Decreased fecundity and egg hatchability were more prevalent when both the male and female pupae were treated compared to the treatment of female pupae only. There was no significant decrease in the fecundity of irradiated adults except 550 Gy, and no eggs hatched at doses of 300 Gy and above.     

Effect of compression on hydroscopicity of extracted Chinese fir heartwood

In order to clarify the effects of extraction and compression on the hydroscopicity of wood, Chinese fir （Cunninghamia lanceolata Hook.） heartwood samples with or without extraction were radially or tangentially compressed under water-saturated condition at room temperature. Warm water and 1% sodium hydroxide were used as different solutions for extraction. Water absorption capacity and moisture adsorption isotherms of the compressed samples were then tested. The fractal dimension of internal wood surfaces （Dfs） was calculated based on adsorption isotherms by FHH equation. Results showed that in both compressed groups, the hydroscopicity of samples extracted by sodium hydroxide solution improved greatly, while that of samples extracted by warm water changed little, compared with that of water-saturated samples. Recovery of set and the change of hydroscopic environment inside wood were main reasons for the difference of water absorption among water-saturated samples and samples extracted with warm water and sodium hydroxide solution. The swelling rate of samples extracted by sodium hydroxide solution significantly increased. Moreover, the swelling rate in the tangential direction of tangentially compressed samples was obviously higher than that in radial direction of radially compressed ones. Dfs values of woods extracted by warm water and sodium hydroxide solution decreased by 0.002 and 0.007 in a radially compressed group and by 0.013 and 0.013 in a tangentially compressed group, compared to those of water-saturated one. Therefore, the conclusion can be made that the extraction and compression treatments used in this study have no obvious effects on internal wood surface.     

Influence of stress level on compression deformation of wood in 170°C transient steam conditions

Abstract

Compression creep experiments of hybrid poplar (Populus deltoides×Populus trichocarpa) were performed in a pressurized vessel equipped with a heated hydraulic press. The viscoelastic response at various stress levels (2–7 MPa), a temperature of 170°C and transient steam conditions was studied. Moisture content and oven-dry density of compressed specimens were determined. While some recovery of compression strain occurred, compression resulted in permanent deformation and increased wood density. The influence of stress level on the amount of set recovery of compressive deformation was evaluated after 24 h water soaking. Applied stress level had a significant effect on the compression deformation. The initial strain, as well as creep strain, varied depending on the applied stress level. The highest oven-dry density was obtained at a stress level of 6.9 MPa. Lower stress levels resulted in lower moisture content after the compression process, while the equilibrium moisture content of compressed specimens was not significantly affected by stress level. Set recovery increased from 20% to 65% with increased stress level from 1.7 MPa to 4.1 MPa, then decreased to 53% for specimens compressed at 6.9 MPa. Moisture content after the compression process significantly affected the set recovery.     

Compressive deformation of wood impregnated with low molecular weight phenol formaldehyde (PF) resin III: effects of sodium chlorite treatment

To obtain high-strength phenol–formaldehyde (PF) resin-impregnated compressed wood at low pressing pressure, we investigated the effects of sodium chlorite (NaClO₂) treatment on wood prior to low molecular weight PF resin impregnation. Sawn veneers of Japanese cedar (Cryptomeria japonica) were treated with 2% aqueous NaClO₂ solution at 45°C for 12 h to remove lignin, and the process was repeated up to four times, resulting in weight loss of 21%. NaClO₂ treatment has shown considerable potential for high compression of PF resin-impregnated wood at low pressing pressure, especially after adding moisture to a content of 10%–11%. This deformation is further enhanced during pressure holding by creep deformation. The density, Young’s modulus, and bending strength of PF resin-impregnated veneer laminated composites that were treated with NaClO₂ four times and compressed at 1 MPa, reached 1.15 g/cm³, 27 GPa, and 280 MPa, respectively. The values in untreated PF resin-impregnated wood reached 0.8 g/cm³, 16 GPa, and 165 MPa, respectively.