nardosinane-type sesquiterpenoids from the formosan soft coral Paralemnalia thyrsoides

Five new nardosinane-type sesquiterpenoids, paralemnolins Q-U (1-5), along with three known compounds (6-8), were isolated from the Formosan soft coral Paralemnalia thyrsoides. The structures of new metabolites were elucidated on the basis of extensive spectroscopic methods, and the absolute configuration of 1 was determined by the application of Mosher's method on 1. Among these metabolites, 1 and 3 are rarely found nardosinane-type sesquiterpenoids, possessing novel polycyclic structures. Compounds 1, 3, 6 and 7 were found to possess neuroprotective activity.     

不同冷链物流过程对金枪鱼品质及组织形态的影响

为研究物流过程中温度变化对金枪鱼品质及组织形态的影响,试验模拟5种不同物流过程,测定金枪鱼肉感官、色差、持水力、质构以及肌纤维间隙。结果表明,超低温冻藏大目金枪鱼肉的品质受物流过程中温度变化影响显著,储运、销售过程始终保持在-55℃的完整冷链下能够使金枪鱼肉保持良好品质;随着储运过程中温度变化次数增多、幅度增大,鱼肉劣化显著,其中,经2次-18℃运输的金枪鱼肉在冻藏末期组织松散、肌纤维间隙达17.20μm,在4℃家用冰箱中贮藏12 h后感官评分、红度值、持水力、硬度和咀嚼性分别为-0.81、5.2、53.08%、1.128 N和58.03,其质量甚至低于物流过程始终保持在-18℃而不产生温度变化的鱼肉。若运输过程不具备超低温冷藏车,仅靠超低温贮藏并不能减缓鱼肉品质劣变,此时应适当调节贮藏温度,尽量避免储运期间的温度变化;相较于2℃冷藏销售,-18℃冷冻柜销售能够使金枪鱼肉保持较好品质。研究结果可为金枪鱼储运和销售提供参考。     

棉花中白色异性纤维的激光成像快速检测方法

现有的棉花异性纤维分拣机采用可见光照明成像,难以识别棉花中混杂的白色异性纤维。为了有效地检测出与棉花颜色相同或相近的白色异性纤维,该文采用线激光照明成像的方法,在固定线激光功率、波长和相机光圈的条件下,利用不同的曝光时间,获取了12种典型的白色异性纤维与皮棉的图像,分析其成像曝光时间与图像对比度之间的关系,发现不同的关系曲线存在一段共有的最优曝光峰值时间。在此曝光时间内,同一图像中的白色异性纤维已经"过曝",而棉花还处于欠饱和状态。二者图像灰度值的明显差异可用于检测棉花中的白色异性纤维。该文在线激光功率为0.8 W,波长650 nm,相机光圈为8C,曝光时间为1.6 ms的条件下获取了1 500幅图像。试验表明,采用简单的固定阈值法,皮棉中12种典型的白色异性纤维的识别率达到了95.8%。研究结果为提高棉花中白色异性纤维的识别率和速度提供了一条新途径。     

Bayesian estimation in maternally ancestral animal models for weaning weight of beef cattle

The Bayesian approach was implemented for fitting several maternally ancestral models for weaning weight data of Angus calves. The goal was to evaluate to what extent genetic evaluation models with additive grand maternal effects (G), or with an ancestrally structured covariance matrix for maternal environmental effects (E), or with a sire × year interaction (ISY), or combinations thereof (GE, GSY, ESY, GESY), redistribute the additive variability and reduce the negative magnitude of the additive correlation between direct and maternal effects (r(AoAm)), when compared with the regular maternal animal model (I). All animals with records had known dams and maternal granddams. The sampling scheme induced low autocorrelations among all variables and tended to converge quickly. The signs of the estimates of r(AoAm) were consistently negative for all models fitted. The magnitudes of the estimates of r(AoAm) from models E, G, GE, ESY, and GESY were almost one-third of those from models I and ISY. Inclusion of the sire × year interaction had some effect in reducing the negative magnitude of r(AoAm), but also reduced the size of the estimates of direct (h(0)(2)) and maternal (h(m)(2)) heritabilities. In comparison, models E or G reduced the negative magnitude of r(AoAm) by 0.50 units and produced more favorable estimates of H(0)(2) and h(m)(2) than models I and ISY. The estimate of h(0)(2) from G was similar to the one from I; however, the estimated h(m)(2) was 0.04 units greater, whereas the estimate of r(AoAm) was much less negative (-0.21 vs. -0.71) than the respective estimates from I. The environmental correlation between the weaning weights of dams and their daughters (λ) was estimated to be -0.28 ± 0.03 in E and ESY, and -0.21 ± 0.03 in GE and GESY. Inclusion of the sire × year interaction effect by itself did not have much of an impact in the reduction of the estimated magnitude of r(AoAm). Rank correlations among EBV for direct effects were larger than 0.94 and did not show any appreciable difference among models, whereas the rank correlation among maternal breeding values displayed differences in the ranking between I and the other models. Models E and ESY recovered the largest amount of total additive variability with maternal effects.     

Immunoadjuvant activities of a recombinant chicken IL-12 in chickens vaccinated with Newcastle disease virus recombinant HN protein

Recombinant fowlpox virus (rFPV/HN) expressing Newcastle disease virus (NDV) HN gene and rFPV/HN/chIL-12 co-expressing chicken IL-12 (chIL-12) and HN (rHN/chIL-12) genes have been characterized. rHN/chIL-12 or rchIL-12, expressed by our previous construct rFPV/chIL-12, co-administered with rHN was assessed for adjuvant activities of chIL-12. Chickens were vaccinated with various amounts of rHN/chIL-12 mixed with mineral oil (MO), intramuscularly. Levels of hemagglutination-inhibition (HI) antibody production depended on the concentration of the injected rHN or rHN/chIL-12. The lower HI antibody titers were obtained in chicken groups rHN/chIL-12/7-rHN/chIL-12/9, receiving 60ng rHN/8ng chIL-12 with MO, 30ng rHN/4ng chIL-12 with MO or 15ng rHN/2ng chIL-12 with MO, respectively, compared to those in chicken groups rHN/7-rHN/9, receiving rHN with MO alone. However, chickens in group rHN/chIL-12/7 or rHN/chIL-12/8 and rHN with MO alone showed the same effective protection. Chicken group rHN/chIL-12/9 was even more protective than that in group rHN/9. When rchIL-12 was co-injected with 15ng rHN plus MO, chickens produced low levels of HI antibody titers; while higher levels of IFN-γ production and an effective protection rate (83%) were obtained. On the other hand, low levels of IFN-γ production and low protection response (50%) were obtained in chickens injected with rHN with MO alone. Taken together, when the concentration of rHN decreased to certain levels, rchIL-12 reduced HI antibody production. The increase in the induction of IFN-γ production might suggest the enhancement of the cell-mediated immunity which conferred the protection from the NDV challenge.     

山地果园索道张紧调节自动控制装置的设计

为进一步提高山地果园中果品农资运输的安全性和可靠性,解决传统索道张紧调节依赖于人力或机械的方法受到使用强度限制,无法对索道运行过程中驱动链张紧进行实时检测,导致张紧调节具有滞后性、自适应不强等问题,该文设计了一种山地果园索道张紧调节自动控制装置,张紧调节采用PID控制算法,可适用于不同负载条件下,实时检测驱动链张紧力变化调整索道驱动链张紧程度。试验结果表明：索道运行过程中,张紧控制系统工作在无控制和PID控制条件下,驱动链分别承受的张紧力均值变化范围为：653.5944～763.4059 N和508.1988～568.7609 N,能有效地实现驱动链张紧自动调节,控制系统最大跟踪误差为104 N,平均误差为13.6417 N。     

单片机在柴油机燃油系检测与诊断中的应用

介绍了由８０３１单片机控制实现的柴油机燃油系性能动态检测与故障诊断系统的结构组成和数据采集方法。系统通过对高压油管内压力波信号与上止点信号的采集、分析，进行燃油系动态性能的检测与故障诊断，并输出检测与诊断数据。     

玉米不同收获期的子粒品质研究

通过３个玉米杂交种、２个播期、４次收获的研究表明：在玉米生理成熟即玉米子粒千粒重最大时，粗脂肪含量最高，质量最佳、尽管粗蛋白相对含量有所降低，但由于子粒产量的增加，使单位面积收获的蛋白产量仍有提高。因此，适时收获不仅可以提高玉米的产量，而且可以改善玉米的品质。     

黄土高原北部坡梁地微地形气候的温度变化特征研究

用多个热敏电阻温度计对准格尔旗五道敖包坡梁地不同部位离地面30,80,150cm的气温进 行测定,结果表明,黄土高原的沟壑地形中,同海拔高度南坡的温度较北坡高,有的高出0．3-0．5℃。近 地面30cm的日平均气温一般高于150cm,有的位点白天温度平均高1．0℃,尤以光照条件好地方明 显;而夜间近地面的温度相对较低。地形影响到温度差异,同时影响到降水的重新分配,进而将影响 到作物的生长发育。     

中华蜜蜂对不同距离和高度的饲喂点的反应

在八叶五加流蜜期和外界缺蜜期，观察中蜂工蜂对不同距离设置的人工饲喂点的采集反应．结果表明，５０只标记蜂对不同距离给饲点的信息传递的有效率和准确率有显著的差异（Ｐ＜０．０１），外界有蜜源会降低标记蜂信息传递的有效性．另一观察表明，中蜂工蜂的信息传递能在一定范围表达食物源的相对高度．