片切磨削方法构造的自由曲面磨削支持系统

以操作者高效准确操作数控磨削中心为目的，开发了自由曲面磨削支持系统，进行了基于球头磨具的磨削中心基础研究。讨论了获得高精度曲面的加工要点，并提出了片切磨削方法。     

甘蔗组培绿苗的分化及游离氨基酸库变化

甘蔗品种仙游79/83的心叶愈伤组织在 N_6培养基中能100%一次诱导成完全苗.诱导分化绿苗过程中,不同培养基从诱导分化的第1天开始,氨基酸总量不断增加,到第18天达最大值.一次诱导分化成的完全苗,不论游离氨基酸的组分或含量都比无根苗的少.组氨酸和色氨酸并不是绿苗分化所必需的氨基酸.此外,不同质量的愈伤组织其氨基酸组分和含量都有差异,说明绿苗的分化可能与氨基酸库有密切关系.     

河蚬酶解液抗氧化作用的研究

以河蚬为原料,对六种蛋白酶的酶解液清除羟自由基的能力进行研究。结果表明:河蚬经酶解后可提高清除羟自由基能力;不同蛋白酶酶解液对羟自由基清除率不同,木瓜蛋白酶酶解液清除能力最强;通过正交优化试验条件:底物质量浓度为40 g/L,木瓜蛋白酶用量为22000 U/g蛋白质,酶解温度45℃,pH=7.5,酶解2 h的酶解液,对羟自由基(.OH)的清除率可达到57.89%。     

Effects of N‐source,light intensity and temperature on nitrogen metabolism of bahiagrass

Under greenhouse conditions, a study was made on the effects of nitrogen (N) source (N)O₃ or NH₄), mode of application (single vs. split) and nitrification inhibition on the N‐uptake and metabolism, of bahiagrass.

Variations in light and temperature in the greenhouse affected the N‐metabolism of bahiagrass plants. Nitrate fed plants had nitrate reductase activity (NRA) pattern different from that of NH₄‐fed plants. Amino‐N accumulation patterns were similar for plants under both N‐sources, although amino‐N levels in leaves of NH₄‐fed plants were much smaller than that of NO₃ plants. Nitrate accumulation in leaves showed inverse trend to that of roots in plants fed both NO₃ or NH₄. To the sharp peaks in NO₃ levels in roots due to increases in light and temperature corresponds a sharp decrease of its levels in leaves.

For both both NO₃ or NH₄ treatments, soluble‐N accumulated most in the rhizomes of bahiagrass plants, whereas protein N accumulated most in leaves, suggesting that rhizomes had a buffering effect on the NO₃ fluxes to leaves. This presumably resulted in a lag in the NRA response of the NO₃‐fed plants to increases in light and temperature.     

磁化水灌溉对镉胁迫下欧美杨Ⅰ-107苗期氮素营养代谢的影响

为探究磁化水灌溉对镉(Cd)胁迫下杨树幼苗营养代谢的影响,以一年生欧美杨Ⅰ-107(Populus×euramericana Neva)幼苗为研究对象,通过磁化处理含Cd(NO₃)₂·4H₂O的1/2 Hoagland营养液浇灌幼苗,测定不同组织的氮素含量、氮素关键代谢酶活性、关键氨基酸含量以及根系形态特征。结果表明,磁化水灌溉使得Cd胁迫下叶片中铵态氮($NH_4^+$-N)、硝态氮($NO_3^-$-N)和全氮(TN)含量增加;同样磁化处理也促进根系中$NH_4^+$-N和TN含量升高,但降低了根系中$NO_3^-$-N含量。磁化水灌溉有利于提高叶片中硝酸还原酶(NR)、亚硝酸还原酶(NiR)、谷氨酰胺合成酶(GS)和谷氨酸合成酶(GOGAT)活性,同时提高根系中NR、GS活性,但对根系中NiR和GOGAT活性有明显的抑制作用。磁化水灌溉促进了Cd胁迫叶片半胱氨酸(Cys)、谷氨酰胺(Gln)的合成,但对谷氨酸(Glu)和甘氨酸(Gly)合成有明显的抑制作用。另外,磁化作用均促进了Cys、Glu、Gln和Gly在根系中的合成。磁化水灌溉可促进杨树根系形态建成。综上可知,磁化水灌溉可通过影响根系形态来调节根系对矿质养分的吸收和运输,可通过刺激氮素代谢关键酶活性来提高氮同化和游离氨基酸的合成,这对于提高杨树对镉污染土壤的适应能力具有重要意义。     

Characteristics of free sesquioxides and humic acids in soil distributed under Warm-temperate forest climate in Nyu mountains,Fukui Prefecture,Central Japan

The activity and crystallinity ratios of free iron oxides, and the ΔlogK and RF values of humic acids were analyzed in five soil types in the Nyu mountains, Fukui Prefecture, to examine the relation between the zonality of soils and the bioclimatic conditions under the Warm-temperate deciduous broad-leaved forest climate. The characteristics of free iron oxides and humic acids were as follows: The Dark red soil, Kunimidake series was a Dark Red soil under the Cool-temperate deciduous broad-leaved forest climate; the Dry brown forest soil (reddish), Tega series was a Yellow-Brown Forest soil under the Warm-temperate deciduous broad-leaved forest climate; the Dry brown forest soil, Takasu-1 series and the Yellow soil, Yada series were Yellow-Brown Forest soils under the Warm-temperate lucidophyllous forest climate; and the Red soil, Oshibayama series and the lower parts of the Tega series were paleo-red soils. These results indicated that zonal soils under the Warm-temperate deciduous broad-leaved forest climate were Yellow-Brown Forest soils in the Nyu mountains, Fukui Prefecture. The Dark red soil, Kunimidake series corresponded to a Hyperdystri-Rhodic Cambisol of World Reference Base for Soil Resources, WRB (FAO, ISRIC, and ISSS: World Soil Resources Reports 84, 1998). The Dry brown forest soil (reddish), Tega series, the Dry brown forest soil, Takasu-1 series, and the Red soil, Oshibayama series were compared with the Hyperdystri-Chromic Cambisol (WRB). The Yellow soil, Yada series was a Hypereutri-Chromic Cambisol (WRB).     

Discrepancies in utilization of density fractionation along with ultrasonic dispersion to obtain distinct pools of soil organic matter

Density fractionation along with ultrasonic dispersion is widely applied in soil science to obtain distinct fractions of soil organic matter. Density cut‐off and dispersion energy are crucial parameters to yield fractions closely corresponding to their conceptual definitions. Our literature review revealed methodological discrepancies in the utilization of density‐fractionation schemes. Strikingly, reasons for the selection of specific density or dispersion energy were rarely explained. Thus, it is not known how results of different approaches relate to each other. We therefore recommend testing and reporting effects of fractionation parameters on chemical and physical properties of fractions, to achieve agreement and coherence on parameters to be used and facilitate comparability in future studies.     

White muscle of masu salmon,Oncorhynchus masou masou,smolts possesses a strong buffering capacity due to a high level of anserine

Masu salmon, Oncorhynchus masou masou, fry were fed with diets containing three different levels of protein for 18 weeks, and the levels of free amino acids and related compounds in the white muscle were compared among the dietary groups and between smolts and parr. The anserine level in the white muscle of smolts was always higher than that of parr, while histidine and glycine levels in the former were always lower than those in the latter, irrespective of dietary treatments. A mixed solution of crystalline anserine, histidine and glycine simulating these amino acid levels in the white muscle of the smolts had a stronger buffering capacity in the physiological pH range than that simulating those levels present in parr. These results suggest that even in freshwater conditions, the white muscle of smolts possesses a more potent buffering capacity than the muscle of parr, for anaerobic burst swimming during the downstream migration. Moreover, the white muscle of smolts fed the high-protein diet had a significantly higher level of anserine than that of smolts fed the low- or intermediate-protein diets, and the solution mimicking the white muscle of smolts fed the high-protein diet showed the strongest buffering capacity among the mixed solutions tested. Thus, a diet with high-protein level could improve qualities of smolts.     

Effect of restricted access to demand-feeders on diurnal pattern of liver composition,plasma metabolites and hormone levels in Oncorhynchus mykiss

In order to study the relative importance of the feeding time and the light/dark alternation, as synchronizers of metabolic and endocrine parameters, the hepatosomatic index, liver glycogen contents, plasma glucose, nonesterified fatty acids, cortisol, growth hormone and thyroid hormone concentrations between dawn −2h and dawn + 12h are described in immature rainbow trout (Oncorhynchus mykiss). Trout were held in groups of 30 individuals and given access to a demand-feeder for only 3h per day, between dawn and dawn + 3h for 6 aquaria, and between dawn + 4h and dawn + 7h for another series of 6 aquaria. There was a clear effect of the time of food access on most of the studied parameters, with a decreased amplitude of variation, or a decreased mean level, in the fish eating in the middle of the photophase, compared with the fish eating at dawn. Superimposed on this apparent depressive effect of phase shifting of food access, some parameters also show direct responses to the shift of eating time, with a post-prandial increase or decrease.

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Résumé Afin d'étudier l'importance relative de l'heure des repas et de l'alternance jour/nuit, en tant que synchroniseurs de paramètres métaboliques et endocriniens ches des truites arc-en-ciel (Oncorhynchus mykiss) immatures, 6 lots de 30 individus, avaient accès à un distributeur d'aliments à la demande durant les 3 premières heures du jour (8h–11h), tandis que 6 autres lots de 30 individus n'avaient accès aux distributeurs d'aliments qu'au milieu de la photophase (12h–15h). Durant les 8 derniers jours, l'indice hépatosomatique, le taux de glycogène hépatique, ainsi que les concentrations plasmatiques en glucose, acides gras non-estèrifiès, cortisol, GH et hormones thyroidiennes ont été suivis entre l'aube 2h et l'aube + 12h. Il a alors été observé un effet significatif de l'heure d'accès à la nourriture sur la plupart des paramètres étudiés, se traduisant par une diminution de l'amplitude de variation de ces paramètres, ou encore une diminution de leurs valeurs moyennes, chez les truites ayant accès à la nourriture au milieu de la période d'éclairement par rapport à celles ayant accès aux distributeurs d'aliments à l'aube. Pour certains paramètres, il a aussi été observé une réponse plus directe, avec un changement post-prandrial des valeurs enregistrées, superposé à cet apparent effet dépresseur du décalage de la phase d'alimentation.

     

Evaluation of feed protein quality by measuring plasma free amino acids in Atlantic salmon (Salmo salar L.) after dorsal aorta cannulation

Two successive experiments were conducted in order to assess plasma free amino acid (FAA) profiles as a method for evaluating protein quality of fish feeds for Atlantic salmon, Salmo salar (L.). In experiment 1, the importance of meal size and inter‐fish variation was assessed by using dorsal aorta cannulated fish and diets that contained different sources of fishmeal (menhaden versus herring) which in the case of herring, had been dried at either 70 or 100 °C. In experiment 2, an attempt was made to mimic a production situation by comparing the FAA profiles in salmon fed diets containing two commercially available fishmeals that had been produced in accordance with industrial standards (Norse‐LT94® and NorSeaMink®; Norsildmel AL, Fyllingsdalen, Norway). FAA profiles in plasma 6 h after feeding were compared with feed true protein digestibility as determined in mink. Cannulated fish, held in individual tanks, were hand‐fed twice daily to pellet rejection (satiety) and daily records of the actual rations consumed were maintained. A total of 24 different amino acids and other amino‐containing compounds were detected using high‐pressure liquid chromatography. Morning and evening meal size showed significant correlations. Meal size had a significant effect on blood levels of the majority of essential free amino acids (EAA) as well as the total sum of FAA (TFAA). In experiment 1, a marked inter‐individual effect was found, possibly because of incipient sexual maturation. FAA profiles were therefore corrected for meal size by linear regression while repeated sampling via the permanently implanted cannula allowed paired comparisons of the different test diets, minimizing inter‐individual variation. Significant differences in plasma FAA profile, EAA and TFAA were detected between fish fed all diets in both experiments. The preceding parameters for fish ingesting each feed were directly related to their respective mink protein digestibility in experiment 1, but not in experiment 2. Our results show that dietary protein quality can be differentiated by the aforementioned protocol, and by using fish with a low metabolic rate feed qualities could be ranked correctly as in experiment 1.