西北地区常见的6种植物挥发性物质抑菌效果研究

选取西北地区常见的月季、连翘、冬青卫矛、紫叶李、国槐、大叶女贞等6种园林植物,测定其叶片挥发性物质对大肠杆菌、金黄色葡萄球菌、枯草芽孢杆菌及酵母菌的抑制作用.结果表明:除紫叶李、大叶女贞对酵母菌无抑制作用外,其他4种植物对供试菌均有较强的抑制作用.月季对4种供试菌的抑制率均在30.00以上,是一种良好的抑菌植物.同时,用2种植物(紫叶李+国槐、紫叶李+大叶女贞、月季+冬青卫矛、紫叶李+连翘)做交叉试验,其对杆菌的抑菌效果较好,交互作用促进了抑菌,抑菌率均在38.00以上,但对于球菌的抑菌作用减弱.     

Within-stem variations in mechanical properties of <Emphasis Type="Italic">Melia azedarach</Emphasis> planted in northern Vietnam

Within-stem variations in the mechanical properties of 17–19-year-old Melia azedarach planted in two sites in northern Vietnam were examined by destructive and nondestructive methods. Wood samples were collected from 10, 50, and 90% of the radial length from pith on both sides (North and South) at 0.3, 1.3, 3.3, 5.3, and 7.3 m heights above the ground. The mean values in whole trees of wood density (WD), modulus of rupture (MOR), modulus of elasticity (MOE), and dynamic modulus of elasticity (E_d) at 12% moisture content were 0.51 g/cm³, 78.58 MPa, 9.26 GPa, and 10.93 GPa, respectively. Within the stem, the radial position was a highly (p?<?0.001) significant source of variation in mechanical properties. MOR, MOE, and E_d increased from pith to bark. WD had a strong positive linear relationship with both MOR (r?=?0.85, p?<?0.001) and MOE (r?=?0.73, p?<?0.001). This suggests that it is potentially possible to improve mechanical properties through controlling WD. MOR had also a strong linear relationship with E_d (r?=?0.84, p?<?0.001). This indicates that E_d is a good indicator to predicting the strength of wood if the density of measured element is known. Besides, the stress wave method used in this study provides relatively accurate information for determining the stiffness of Melia azedarach planted in northern Vietnam.     

多菌种混合发酵玉米秸秆生产含酶蛋白饲料的研究

采用多荫种混合共发酵方式,将选育出的高活性黑曲霉、康氏木霉、瘤胃细菌、瘤胃酵母分步接种于用氨化法和白腐真菌前处理过的玉米秸秆上共发酵.结果表明,分步接种最佳时间为:白腐真菌接种3 d后接种康氏木霉、黑曲霉和瘤胃细菌,再发酵3 d后接种酵母,最后共发酵2 do利用正交试验得出最佳培养基配比为:玉米秸秆粉:麸皮为1:1,物料:水为1:4,(NH<,4>)<,2>SO<,4>用量为3.0%,微量元素混合液0.02%(Fe:Zn:Co:Mn=5.0:4.5:3.8:3.8),MgSO<,4>·7H<,2>O 0.02%,KH<,2>PO<,4> 0.4%,CaS04 0.4%.pH为5.5,发酵温度为30℃时,发酵8 d后,纤维素降解率为52.67%,粗蛋白含量可达29.41%,提高了3.93倍.     

Determination of polychlorinated biphenyls by GC/MS with ultrasound-assisted extraction from shellfish

An efficient extraction method by ultrasound-assisted extraction (UAE) was developed for the extraction of polychlorinated biphenyls (PCB 28, 52, 101, 118, 130, 153, 180) from various shellfish. Analytes were determined by gas chromatography-mass spectrometry in selected ion monitoring (SIM) mode. All the samples were extracted by n-hexane and decontaminated by concentrated sulfuric acid. The resulting samples were determined by quantitative detection by comparing with external standards. The average recoveries of seven kinds of PCBs ranged from 80.92% to 93.89%, and the lowest detectable limit was 0.08-0.03 μg·kg⁻¹. The average concentrations of total PCBs were 14.12–30.61 μg·kg⁻¹ in the samples. This method was highly effective in reducing the cost and time for the pretreatment of samples. This method may be applied for the screening and monitoring of shellfish for organic pollutants in coastal waters.     

活性硒元对油茶产量的影响及其在果实中的分布

生物活性硒元是近年开发的一种全新的有机富硒植物营养素。为了探讨活性硒元对油茶产量和品质的影响与作用,以优良油茶品种的2～4年生幼林和10年生成熟林为研究对象,共设3个随机区组、6个处理(即CK0、CK1、CK2、Ⅰ、Ⅱ、Ⅲ,其中以处理Ⅱ为推荐处理),就富硒肥的施用效果问题进行了校验试验。结果表明:以活性硒元土壤赋存复合肥(以下简称为"活性硒元")处理Ⅰ、Ⅱ、Ⅲ的油茶成林与幼林的果实产量明显高于各对照(CK)组,且推荐施肥处理Ⅱ的增产效果最为明显,不同处理间油茶产量的差异显著(p<0.05),说明活性硒元的施用对油茶产量有显著的影响,而尤以处理Ⅱ的影响最为显著;活性硒元各处理组油茶果实中的硒含量明显高于各对照(CK)组,且其含硒量随着硒元水平的增加而增加,其中,种仁的含硒量最高,成林种仁中的含硒量为0.127～1.042 mg/kg,幼林种仁中的含硒量为0.119～0.866 mg/kg,果皮中的次之,种皮中的含硒量最低。     

Application of ELISA-based kit for detecting AOZ and determining its clearance in eel tissues

Furazolidone, an antibacterial drug that was once widely used in the livestock industry and aquaculture, is now prohibited in numerous countries. It is difficult to detect residual furazolidone because it is readily metabolized in animal tissues but, by using and liquid chromatography coupled with tandem mass spectrometry, its metabolite, 3-amino-2-oxazolidinone (AOZ) can be detected. Here we describe the validity of an enzyme-linked immunosorbent assay (ELISA) kit to detect AOZ in Japanese eel Anguilla japonica tissue. ELISA is capable of detecting AOZ at 1.0 μg/kg in an eel sample with excellent accuracy and precision. Our results show that ELISA is suitable for regulatory purposes and for studying the fate of AOZ residues in eel treated with furazolidone. To measure the persistence of AOZ in eel tissues, eels (1.4–6.5g) were immersed in tanks containing 2 and 10 mg furazolidone/L for 3 h, and then maintained in a tank supplying well water for the next 160 days. The half-lives of AOZ, calculated from the linear terminal part of the excretion curve, were 25.0 days in muscle and 21.6 days in liver from fish exposed to 2 mg/L furazolidone. In the eels treated with 10 mg/L furazolidone, by contrast, high levels of AOZ were detected in liver and muscle, but the half-lives of AOZ were similar to those in fish treated with 2 mg/L furazolidone. The half-lives of AOZ in eel tissues were prolonged by the condition of low water temperature.     

Mechanical insights into the effect of fluctuation in soil moisture on nitrous oxide emissions from paddy soil

Paddy fields are subjected to fluctuating water regimes as a result of the alternate drying and wetting water management, which often incurs a sensitive change in N₂O emissions from paddy soils. However, how the soil moisture regulates the emission of N₂O from paddy soil remains uncertain. In this study, three incubation experiments were designed to study the effects of constant and fluctuating soil moisture on N₂O emission and the sources of N₂O emission from paddy soil. Results showed that the N₂O emission from paddy soil at 100 % WHC (water-holding capacity) was higher than that at 40, 65, 80, 120, and 160 % WHC, indicating that 100 % WHC was the optimum soil moisture content for N₂O emission under the incubation experiment. Small peak of N₂O flux appeared when the soil moisture content from 250 % WHC decreased near to 100 % WHC, lower than that triggered by nitrogen (N) fertilization, which was mainly owing to the low NH₄ ⁺ concentration at this period. Nitrification dominated the emissions of N₂O from paddy soil at 250 % WHC (54.96 %), higher than that of nitrification-coupled denitrification (6.74 %) and denitrification (38.3 %). The contribution of denitrification to N₂O emissions (44.10 %) was equivalent to that of nitrification (44.45 %) in soil at 100 % WHC, which was higher than that of 250 % WHC treatment. In conclusion, the finding suggested that the peak of N₂O in paddy soils during midseason aeration could be attributed to the occurrence of optimum soil moisture under sufficient N availability, favorable for the production and accumulation of N₂O.     

Prevalence and risk factors of mycobacterial infections in farm and trade cattle in southwestern Nigeria

We evaluated the prevalence of mycobacterial infections (i.e., Mycobacterium bovis and non-tuberculous mycobacteria [NTM]) and their associated risk factors among cattle herds and trade cattle in southwestern Nigeria. Through cross-sectional study design, cattle herds from three locations were screened using the single intradermal comparative cervical tuberculin test based on two diagnostic standards; more than 4 mm (? 4 mm) and more than 2 mm (? 2 mm) cut-off points. Abattoir study involved screening trade cattle for tuberculous lesions. Overall, 515 cattle from 45 herds were screened. Using >?4 mm, animal level and herd prevalence of 11.7 and 46.7% were recorded, respectively. Applying the ? 2 mm cut-off, animal level and herd prevalence increased to 31.1 and 60.0%, respectively. Significantly, using the ? 2 mm cut-off, cattle in medium size herds/extensive management system (OR?=?1.6; 95% CI 1.1–2.5) and Sokoto Gudali (OR?=?2.3; 95% CI 1.4–3.8) were more at risk of being positive reactors, while Rahaji (OR?=?0.3; 95% CI 0.1–0.7) breeds of cattle and cows in the peri-urban area (OR?=?0.4; 95% CI 0.2–0.9) were less at risk of being positive reactors. Again, M. avium reactor of 21.7% was observed. In the abattoir, 1797 cattle were examined with 126 lesions suggestive of tuberculosis (TB). Culture/molecular analyses confirmed 2.2% M. bovis and 0.9% NTM infections. Risk factors associated with bovine TB among trade cattle were sex (OR?=?4.0; 95% CI 1.2–13.5) and age (OR?=?0.3; 95% CI 0.1–0.9). We confirm 11.7% prevalence of mycobacterial infections among populations of cattle screened with breed and herd size being major risk factors.     

不同水分处理对冬小麦产量和水分利用效率的影响

为探明甘肃河西走廊地区不同水分处理对冬小麦产量和水分利用效率的影响,以冬小麦临抗2号为试验材料,在冬灌水(180mm)相同的条件下,其他生育期以灌水量和灌水次数不等共设置5个处理。结果表明,返青期各层土壤有效含水量(AWC)均较低(2.37mm),至拔节期突增(9.88mm),随着生育期的推进,逐渐降低,成熟期降至2.54mm,特别是处理W1和W2在成熟期0～60cm层处于萎蔫点以下。处理间AWC的差异在灌浆期表现最为明显,尤其处理W1和W3,在0～60cm层AWC呈显著(P<0.05)和极显著(P<0.01)差异。冬小麦日耗水强度最大的时期是抽穗～开花期,阶段耗水量最大的时期是播种～返青,冬灌水充足是保证出苗率和后期冬小麦的正常生长基本条件。处理W3具有最高籽粒产量(6296.52kg/hm²)、千粒重(53.12g)和单位面积穗数(61.83万穗/hm²),但相对灌水较少的处理W4(籽粒产量6240.37kg/hm²)而言,其水分利用效率(WUE)和灌溉水利用效率(IWUE)均较低。相关分析表明,产量与千粒重(R=0.99^**)、WUE(R=0.97^**)、开花期～成熟期耗水量(CA_m)(R=0.88^*)、全生育期耗水量(CA_t)(R=0.88^*)呈极显著(P<0.01)正相关,表明生育后期水分胁迫,加速了冬小麦的衰老进程,灌浆期缩短,千粒重下降,最终表现为产量下降。综合考虑各种因素,处理W4具有重要的推广价值。     

乌鲁木齐市动物源性食品中兽药残留分析与评价

为了解乌鲁木齐市动物源性食品中的兽药残留情况,采用高效液相色谱法(HPLC)对14种兽药在动物源性食品中的残留量进行检测.结果表明:伊维菌素、呋喃唑酮、磺胺嘧啶、磺胺间甲氧嘧啶、磺胺二甲嘧啶、磺胺甲基异口恶唑均有不同程度的残留量,其余未见检出.检出率依次为89;、30;、28;、4;、70;和22;.其中磺胺类药物与呋喃唑酮残留问题较突出,超标率分别为66;和30;,将其作为乌鲁木齐市兽药残留监控的主要药物是很必要的.