The wettability and bonding performance of densified VTC beech (Fagus sylvatica L.) and Norway spruce (Picea abies (L.) Karst.) bonded with phenol–formaldehyde adhesive and liquefied wood

The influence of viscoelastic thermal compression (VTC) on surface wettability and bonding performance of wood was evaluated. Low quality beech (Fagus sylvatica L.) and Norway spruce (Picea abies (L.) Karst.) were densified with the VTC process to different degrees of densification. Control and densified strips were bonded with phenol–formaldehyde (PF) adhesive and liquefied wood (LW). Shear strength of bonded assemblies was determined after 1 week of conditioning at 20 °C and relative humidity of 65 %. Wettability was determined on the basis of the contact angle of water, PF adhesive, and LW using the Wilhelmy method. Results showed that densification of beech and spruce wood did not significantly affect the shear strength of specimens bonded with PF adhesive. In beech assemblies bonded with LW shear strength decreased significantly with increased density, whereas in bonded spruce specimens decrease of shear strength was not significant. It was found that degree of densification and bonding process used in the study were not appropriately chosen for spruce wood specimens, since major deformations after the bonding process occurred. Wettability changed significantly after densification. Contact angle of water and LW increased after densification, whereas contact angle of PF showed inverse trend and decreased after VTC process. Furthermore, the degree of densification had a minor effect on the wettability.     

Biological importance of γ-glutamyl-S-methylcysteine of kidney bean (Phaseolus vulgaris L.)

The effects of S-methyl-L-cysteine (SMC) on growth and food intake by rats were investigated and in vivo absorption studies of gamma-glutamyl-S-methyl-L-cysteine and free SMC were performed. The results showed that the peptide is slowly absorbed and only free SMC could be detected in the blood. The diets (10% casein), containing SMC, depressed food intake and animals’ growth. Both effects were proportional to the SMC contents in the diets. The results obtained with pair-fed groups led to the conclusion that the depression in growth was caused by the refusal of the SMC diets. The addition of cystine to the SMC diet only partially restored normal growth. Histological examination of livers, kidneys and spleens of rats fed with SMC showed no tissue alterations, except for a significant increase in the kidney weights. The hematological features did not show any significant differences, but there was a slight increase in erythroid precursors and young forms in the bone marrow, which might indicate an increased erythrocyte turnover. These results suggest that the reduction in food intake could be associated with some defence mechanism against toxic substances.     

Bending performance of 3-layer beech (Fagus sylvativa L.) and Norway spruce (Picea abies (L.) Karst.) VTC composites bonded with phenol–formaldehyde adhesive and liquefied wood

Low quality beech (Fagus sylvatica L.) and Norway spruce (Picea abies (L.) Karst.) were densified with viscoelastic thermal compression (VTC) process to two different degrees of densification, and lamellas were used to manufacture different types of 3-layer VTC composites. Bending properties of 3-layer VTC composites bonded with phenol formaldehyde (PF) adhesive and liquefied wood (LW) were determined and compared to 3-layer composites produced with undensified beech or spruce wood lamellas. Morphology of VTC spruce wood of higher density was analysed with fluorescent microscopic technique. All composites produced with densified beech lamellas and bonded with PF adhesive had significantly higher values of modulus of rupture (MOR) and modulus of elasticity (MOE) than composites produced with undensified lamellas. Densified spruce lamellas contributed to better bending performance of 3-layer VTC composites bonded with PF adhesive to some extent. Furthermore, composites bonded with LW had significantly lower MOR and MOE values compared to composites bonded with PF adhesive. Study of VTC spruce wood microstructure showed that densification caused non-uniform deformation of cell wall structure, in which cell wall fractures were observed.     

Effect of γ-irradiation on the antioxidant activity of turmeric (Curcuma longa L.) extracts

Effect of γ-irradiation (10KGy) on the antioxidant property of turmeric extracts was investigated. γ-irradiated as well as non-irradiated turmeric samples were subjected to successive solvent extraction using hexane, benzene, and 80% aq. methanol. Benzene extract, containing mainly curcuminoids were subjected to column fractionation in order to isolate the individual curcuminoids. The curcuminoid analogues as well as the above fractions were then tested for their antioxidant activity by measuring thiobarbituric acid value (TBAV) and peroxide value (PV) based on the air oxidation of linoleic acid. γ-irradiation at a dose of 10KGy did not affect the antioxidant activity of turmeric extracts studied.     

Effects of γ-irradiation on the biological activity of burdock (Arctium lappa L.) extracts

Burdock (Arctium lappa L.) extracts were prepared with different extraction methods, ethanol (70%, RT) and hot water (85°C for 3 hr, HT), and their biological activities were investigated after γ-irradiation (10 and 20 kGy). Color of the burdock extracts became brighter after application of irradiation regardless of the extraction system. The 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity of the burdock extracts with RT and HT were 54.56 and 59.21% at 500 ppm, respectively, and the lipid oxidation of oil emulsion was delayed by addition of the extracts. The HT29 cancer cell viability was inhibited by burdock extracts with RT up to 52.45 at a 250 ppm level. The anti-mutagenicitiy against 3-amino-1,4-dimethyl-5H-pyrido[4,3-b]indole and 2-nitrofluorene were also found. Results indicate that burdock extract possesses biological activities and RT showed an increasing trend in antixodiative activity and inhibition of cancer cell viability. Brighter color of the burdock extract after irradiation may improve industrial applicability.     

Effect of γ-irradiation on antioxidant activity of black pepper (Piper nigrum L.)

Antioxidant activity and EPR investigations of irradiated ground black pepper (Piper nigrum L.) were evaluated. The black pepper was exposed to γ-irradiation at doses from 5 to 30 kGy. The effect of irradiation on antioxidant properties of black pepper extracts was investigated by radical-scavenging effect on 1,1-diphenyl-2-picrylhydrazyl (DPPH) radicals, by determination of reducing power and content of thiobarbituric acid-reactive substances. Some significant changes were observed in creation of thiobarbituric acid-reactive substances (TBARS). Difference between non-irradiated and irradiated samples at the legal European limit dose of 10 kGy reached, on average, 23% and, at the Food and Drug Administration (FDA) 30 kGy limit, 33%. Irradiation affected significantly the DPPH radical-scavenging activity and reducing power of ground black pepper extracts. The γ-radiation treatment of ground black pepper samples observed by EPR, resulted in the production of three paramagnetic species (GI–GIII) characterized by different origin, thermal behaviour and stability. The axially symmetric EPR resonances, GI and GII, were assigned to the carbohydrate radical structures. The spin Hamiltonian parameters of GIII possessed the characteristic features of “cellulosic” radical species. The EPR measurements, performed 20 weeks after the radiation process, confirmed that temperature increase from 298 to 353 K, caused significant decrease of integral EPR signal intensity for γ-irradiated samples (∼40%), compared to the reference (non-irradiated) ground black pepper, where only 13% drop was found. Significant correlation between EPR and thiobarbituric acid methods was assessed by study of antioxidant activity changes in relation to irradiation doses and also in the case of spice storage, between EPR and reducing power methods.     

生菜(Lactuca sativa L.)多酚氧化酶特性研究

以散叶生菜为原料,研究提取液用量、底物浓度、反应体系pH值和温度、抑制剂对生菜多酚氧化酶(PPO)活性的影响。结果表明:以邻苯二酚为底物,生菜PPO在420nm波长下吸光度最大;磷酸缓冲液(mL)与生菜质量(g)比为1.5∶1时,提取液中PPO活性较强;最适pH值为8.0、最适温度为30℃、最适底物浓度为0.3 mol/L。抑制剂对PPO酶抑制效果依次为抗坏血酸﹥柠檬酸﹥NaCl;此外,生菜叶脉中PPO活性为叶片中PPO活性的5.72倍。     

Flavon(ol)glykoside der Puffbohnenbl?tter (Vicia faba L.) und des Feldsalats [Valerianella locusta (L.) Betcke]

Zusammenfassung Aus Puffbohnenblättern wurden neben Rutin (Qercetin-3-rutinosid) Kämpferol- und Quercetin-3-O-ß-d-glucosyl-7-O-rhamnoside sowie Kämpferol-3,7-O-bis-ß-d-glucosid isoliert und identifiziert. — Feldsalat enthielt hauptsächlich Luteolin-7-O-rutinosid. Daneben wurden wahrscheinlich Luteolin-7-O--d-glucosyl-4-O-arabinosid sowie Spuren Rutin aufgefunden.

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Flavone and flavonol glycosides of leaves of broad beans (Vicia faba L.) and cornsalad [Valerianella locusta (L.) Betcke]10. Flavonols and flavones of vegetables

Summary Leaves of broad beans contained kaempferol and quercetin 3-O--d-glucosyl-7-O-rham-nosides, kaempferol 3,7-O-bis--d-glucoside and rutin (quercetin-3-rutinoside). Cornsalad contained mainly luteolin 7-O-rutinoside, probably luteolin 7-O--d-glucosyl-4-O-arabinoside and traces of rutin.

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9. Mitt: Galensa R, Herrmann K (1979) Z Lebensm Unters Forsch 169:170. Auszug aus der Promotionsarbeit von J. Knackstedt: Über die Flavon(ol)glykoside von Lorbeerblättern, Sternanis, Feldsalat und Puffbohnen. Diss. Univ. Hannover 1981     

The influence of storage on aroma, soluble solids, acid and colour of sour cherries (Prunus cerasus L.) cv. Stevnsbær

The present study involved a laboratory scale experiment where the impact of post-harvest storage on the quality of sour cherries (Prunus cerasus L.) cv Stevnsbær was investigated. Cherries were stored for 7 days at temperatures of 2??°C, 10??°C, 20??°C, and 30??°C, and at 20??°C in combination with a 20% CO₂ atmosphere. Cherry quality was assessed by analysis of soluble solids, titrateable acids, anthocyanins and aroma compounds. The content of soluble solids of cherries decreased at storage temperatures above 10??°C. The anthocyanin content of cherries decreased during storage at all temperatures. A decrease, followed by an increase, in titrateable acid was observed for all temperatures except 2??°C. Aroma components were also affected by storage time and temperature. The level of benzaldehyde decreased during storage at higher temperatures, while those of eugenol and vanillin increased at all temperatures. The levels of "off" odour compounds, like acetic acid and fermentation alcohols, increased at higher temperatures during storage. The CO₂-enriched atmosphere (20%?CO₂) did not affect the different quality factors significantly.     

Die Xylemleitquerschnitte von Fichten (Picea abies (L.) Karst.) unterschiedlicher Vitalitätsgrade and Altersklassen

In mountaineous regions of Germany Norway Spruce (Picea abies Karst.) the most common and the most important tree species is severely affected by forest decline. At Göttingen University an integrated research project is conducted to analyse qualitative and quantitative relations between site quality, pollution (immision) and physiology and vitality of the affected trees. Within that context it is of particular interest to know if the conductive structure of the tree’s xylem can become a limitation for transport of water between the roots (as uptaking parts) and the crown/needles (as evaporating parts) of the hydraulic system. A total of 108 trees out of 5 young stands (appr. 40 yrs.) and 2 old stands (appr. 120 yrs.) situated in the Harz mountains and nearby have been intensively analysed. Two of the stands are severely affected by forest decline, and showed heavy needle-loss in the crowns, the other trees were obviously in normal, vital conditions. On cross cuts of 4 different levels (heights) of the trees, the following variables had been measured Absolute sapwood-area, density (ovendry), relative moisture content, water content of the xylem and cross-sectional area of conductive tissue in the sapwood. The results show clearly, that

• - the sapwood-area in the affected trees is lower than in the vital trees. The relative sapwood area increased from the bottom to the top of all trees, independent from their vitality.
• - the density raised from the pit to the bark of the stem, subvital trees showed higher densities.
• - the moisture content of the sapwood of the vital trees was higher than that of the subvital trees.
• - there is a clear distinction in moisture content between heartwood, inner sapwood and outer sapwood. This supports the hypothesis, that the latter is primarily responsible for the water conduction.
• - there was an inverse correlation between the area of the lumina of tracheids (“pores”) and the density, the subvital trees showed a lower area of pores compared with the vital trees.
• - the sapwood area showed high correlation with the ovendry weight of the total needles of the tree, this correlation can be even improved if the proportion of pores within the sapwood area and its water content are calculated as additional variables.

     

Effect of enzyme treatment with β-glucosidase on antioxidant capacity of mulberry (Morus alba L.) leaf extract

This study was carried out to investigate the effect of enzyme treatment with β-glucosidase on antioxidant capacity of the mulberry leaf extract (MLE) using oxygen radical absorbance capacity (ORAC) and cellular antioxidant capacity (CAC) assay. The MLE was prepared by autoclaving at 121°C for 15 min and treated with β-glucosidase for 9 hr. High pressure liquid chromatography (HPLC) analysis showed that only qercetin-3-β-d-glucose (QT-G) among quercetin (QT) glycosides of MLE, including QT-G, quercetin-3-O-glucose-6″-acetate (QT-GA), and rutin (RT), was converted into QT by 3 hr treatment with β-glucosidase. The in vitro peroxyl radical- and hydroxyl radical scavenging capacity significantly increased after the enzyme treatment using β-glucosidase for 6 and 9 hr, respectively. The metal chelating activity increased after the enzyme treatment using β-glucosidase for 3 hr. The intracellular antioxidant capacity of MLE to protect AAPH- and Cu²⁺-induced oxidative stress in HepG2 cells significantly increased after the enzyme treatment using β-glucosidase for 3 and 6 hr, respectively, indicating that QT may be released from QT-G by β-glucosidase and penetrate into cell membrane so that it can contribute to the intracellular antioxidant capacity of MLE.     

玉米象(Sitophilus Zeamais Motschulsky 1855)

玉米象是属于象鼻虫科的一种害虫,为害贮粮甚烈。近200年来,各国昆虫分类学家,对于玉米象、米象(Sitophilus oryzae Linne 1763)、小米象(Sitophilus sasakii Takahashi 1928)进行了详细的研究,对这一类种群才逐步澄清,认为是独立的种。对于这三种学名混用,特征混淆,习性交错使用的情况在国内外的文献中屡见不鲜。米象是林奈于1763年在法国的Surinum地方的大米中发现,并定名为Curculio oryzae Linne。这是米象的最初记录。 Motschulsky于1855年发现南美粮食中的是林奈所描述的米象(C.oryzae)的大型种     

甜菜(Beta Vulgaris L.)染色体组型的研究

研究甜菜(Beta Vulgaris L.)的染色体组型,对甜菜的分类、进化、遗传和育种等都有重要的意义,同时也是细胞生物学和细胞遗传学的基础工作之一。甜菜染色体较小,多数染色体总长和臂比等仅存在较小     

石莼(Ulva lactuca L.)营养成分及多糖组成分析

为使人们对石莼的食用价值有更加深入的了解,扩展其消费市场,促进石莼资源的开发及高值化利用,本文对石莼的主要营养成分、氨基酸组成、部分微量元素含量进行了测定,同时对其主要活性成分石莼多糖进行了红外光谱与单糖组成分析。结果表明,石莼中蛋白质、碳水化合物、粗纤维、脂肪、灰分含量分别为(%):22.03、38.00、8.77、1.11、30.09,富含人体必需的Ca、Mg、Fe等微量元素,氨基酸种类齐全且必需氨基酸含量高达5.90 g/100 g;经红外光谱与高效液相色谱分析表明,从石莼提取出的石莼多糖的主要单糖组成为鼠李糖(45.23%)、木糖(26.04%)和葡萄糖(23.73%),且有糖醛酸与硫酸基存在。     

SPME-GC-MS法测定朝鲜蓟(Cynara scolymus L.)中的风味成分

采用固相微萃取-气相色谱-质谱联用法(SPME-GC-MS)测定朝鲜蓟中的挥发性成分.通过对朝鲜蓟的3个部分(可食中、可食边、不可食)的分析,分别得到17、17、21种挥发性成分.3个部分中所含相同的成分为4(14),11-桉叶二烯和石竹烯,且4(14),11-桉叶二烯的含量较高(约50%).     

甜菜(Beta vulgaris L.)愈伤组织的创造

绪言在农作物的组织培养中,用菸草(Nic—otiana tabacum)来培养单倍体以及用原生质融合和植株再生的体细胞杂交来培养单倍体已引起育种工作者的很大关注。有几个植物属已创造了单倍体,在其他植物属已确定了组织培养创造单倍体。     

紫皮豇豆(Vigna unguiculata L.)花色苷的研究

首次应用高效液相色谱-二极管阵列检测器-质谱联用技术(HPLC-DAD-MS)鉴定出紫皮豇豆主要含有三种花色苷,分别为飞燕草色素、矢车菊色素、天竺葵色素的葡萄糖苷,其中矢车菊葡萄糖苷相对百分含量达到93.4%;应用pH示差法测定出其单体花色苷的含量为57.15mg/100g鲜重;应用DPPH法测定结果显示,花色苷粗提液有较强的抗氧化能力。