3种饲料添加剂对吉富罗非鱼幼鱼生长性能、消化酶活性和肝、肠组织结构的影响

为探讨中草药提取物、胆汁酸、微生态制剂对吉富罗非鱼(Oreochromis niloticus)生长性能、消化酶活性和肝、肠组织结构的影响,以基础饲料为对照,分别在每千克基础饲料中添加中草药提取物(1、2 g)、胆汁酸(0.1、0.2 g)、微生态制剂(1、2 g)配制成6种试验饲料,选取平均体质量为(32.75±5.75)g的吉富罗非鱼幼鱼483尾,随机分为7处理,每处理3平行,每平行23尾,共进行养殖实验45 d。结果显示:与对照组相比,低剂量使用此3种添加剂均有改善实验鱼生长和饲料利用的趋势。饲料中添加胆汁酸显著提高了吉富罗非鱼的增重率和特定增长率;饲料中添加微生态制剂组的吉富罗非鱼的肥满度最大,但各处理组之间差异不显著;中草药组的增重率与特定生长率与对照组之间无差异。饲料中添加微生态制剂和0.1 g/kg胆汁酸的实验鱼肠道脂肪酶活性显著高于中草药提取物2 g/kg的处理组;各组间的肠道淀粉酶、蛋白酶活性差异不显著。与对照组相比,各处理组实验鱼的前肠绒毛个数和肌肉层厚度有增加的趋势;添加1 g/kg微生态制剂的实验鱼中肠绒毛长度显著高于中草药组。结果表明:饲料中添加1 g/kg中草药提取物,0.2 g/kg胆汁酸,1 g/kg微生态制剂可在一定程度上提高吉富罗非鱼幼鱼的生长性能。大北农水产科技集团企业自立项目(DBN-A-E20160001

Acoustic inspection of wall hollowing based on SPCE61A single-chip microcomputer

针对建筑外墙空鼓的检测要求,利用振动与声学理论进行敲击过程的建模和敲击声学特性分析,在此基础上设计了一个基于16位凌阳单片机SPCE61A的嵌入式墙体无损检测系统。由于SPCE61A片内资源有限,通过片内资源的高效调配设计及算法优化实现多点数快速傅立叶计算,提高系统检测性能。实验数据表现的敲击声中低频段能量比与墙体结构的关系与理论分析基本吻合。门限检测方法对墙体进行识别,取100个好墙体的敲击声在9kHz处平均能量的0.6倍作为门限进行检测。实测200次敲击,正确识别率高达99%。如果环境噪声较大,而仍利用门限检测方法,则正确率识别率下降较大。实验结果表明了该系统的有效性。To tackle the safety threats caused by the wall hollowing,this paper designs an acoustic no-ndestructive inspection system based on embedded Sunplus SPCE61A single-chip microcomputer. The imp-act process and the resulting sound emission are analyzed theoretically to obtain the relationship between the hollow wall and the corresponding acoustic feature. Due to the limited on-chip memory capacity of the SPCE61A,the present system adopts the memory distribution and Fast Fourier Transform (FFT) algorithm optimization to realize 256-point FFT computation to ensure the detection performance. Experimental res-ults demonstrate the effectiveness of the present system,which has the potential of being developed as a portable,convenient,accurate and low-cost inspection tool.福建省科技计划重点项目(No.2007H0030);; 香港特区政府RGC项目(No.CityU 1166/02E)资助

锂氧电池双功能还原石墨烯-LaFeO复合纳米催化剂的制备及性能

制备具有氧还原（ORR）与氧释放（OER）双功能催化活性的特殊孔道结构电催化剂是锂氧电池研究的挑战之一。本文以氧化石墨烯、硝酸铁、硝酸镧、柠檬酸为原料,结合溶胶凝胶和水热合成方法,制备出还原氧化石墨烯（RGO）与铁酸镧（LaFeO）复合的双功能催化剂（RGO-LaFeO）。X射线衍射（XRD）、傅里叶变换红外（FTIR）光谱和Raman光谱分析结果确认该复合催化剂由纯相钙钛矿结构LaFeO和还原氧化石墨烯组成,扫描电子显微镜（SEM）观察到LaFeO纳米颗粒均匀地负载在RGO片层表面。锂氧电池测试结果指出,相对于LaFeO纳米粒子（NP-LaFeO）,RGO-LaFeO催化剂具有更好的ORR和OER催化活性,归因于RGO特殊的三维导电多孔结构与LaFeO纳米粒子的协同催化作用。以RGO-LaFeO作为阴极催化剂的锂氧电池在限1000 m Ah?g比容量、100 m A?g电流密度条件下,可实现36周稳定的充放电循环,展示出良好的应用前景。国家自然科学基金(21621091)；国家重点研发计划(2016YFB0100202)资助项目~~

Reduced Graphene Oxide-LaFeO3 Composite Nanomaterials as Bifunctional Catalyst for Rechargeable Lithium-Oxygen Batteries

制备具有氧还原(ORR)与氧释放(OER)双功能催化活性的特殊孔道结构电催化剂是锂氧电池研究的挑战之一。本文以氧化石墨烯、硝酸铁、硝酸镧、柠檬酸; 为原料,结合溶胶凝胶和水热合成方法,制备出还原氧化石墨烯(RGO)与铁酸镧(LaFeO_3)复合的双功能催化剂(RGO-LaFeO_3)。X射线; 衍射(XRD)、傅里叶变换红外(FTIR)光谱和Raman光谱分析结果确认该复合催化剂由纯相钙钛矿结构LaFe03和还原氧化石墨烯组成,扫描电子; 显微镜(SEM)观察到LaFe03纳米颗粒均匀地负载在RGO片层表面。锂氧电池测试结果指出,相对于LaFe03纳米粒子(NP-LaFeO_3),; RGO-LaFeO_3催化剂具有更好的ORR和OER催化活性,归因于RGO特殊的三维导电多孔结构与LaFeO_3纳米粒子的协同催化作用。以RGO; -LaFeO_3作为阴极催化剂的锂氧电池在限1000 mAh·g~(-1)比容量、100; mA·g~(-1)电流密度条件下,可实现36周稳定的充放电循环,展示出良好的应用前景。Development of electrocatalysts is one of the challenges in the development of the lithium-oxygen battery, especially the synthesis of catalysts with special pore structures and excellent bifunctional catalytic performance for both the oxygen reduction reaction (ORR) and the oxygen evolution reaction (OER). In this article, a reduced graphene oxide-LaFeO3 (RGO-LaFeO3) nanocomposite electrocatalyst was synthesized by combining sol-gel and hydrothermal methods and using graphene oxide, lanthanum nitrate, ferric nitrate, and citric acid as raw materials. The prepared samples were characterized by X-ray diffraction, Fourier transform infrared spectroscopy, Raman spectroscopy, and scanning electron microscopy. The results confirmed that the RGO-LaFeO3 was composed of pure phase LaFeO3 with a perovskite structure and RGO and that the LaFeO3 nanoparticles were loaded uniformly on the RGO layer surface. In comparison with a LaFeO3 nanoparticle (NP-LaFeO3) catalyst, RGO-LaFeO3 exhibited superior activity for both the ORR and the OER when it served as the cathode of a lithium-oxygen battery. The higher catalytic activity of the RGO-LaFeO3 is attributed to the synergistic effect of the special three-dimensional electronic conductive structure of RGO and the intrinsic catalytic property of LaFeO3. It was shown that the lithium-oxygen battery with the RGO-LaFeO3 cathode can be cycled stably up to 36 reversible cycles under conditions of a limit discharge depth of 1000 mAh.g(-1) and a 100 mAg(-1) current density for charge-discharge. The study illustrates that the RGO-LaFeO3 bifunctional electrocatalyst is a promising candidate for the cathode in lithium-oxygen batteries.National Natural Science Foundation of China [21621091]; National Key; Research and Development Program of China [2016YFB0100202

HBV整合的致癌性研究

HBV的4个亚基因产物中,HBx具有反式激活、介导细胞凋亡作用,HBs具有反式激活因子的作用。肝细胞癌(HCC)的发生与HBV的整合及整合后染色体重排有关。为探讨HBV整合及HBx、HBs亚基因在HCC发生中的可能作用,我们制备了HBV亚基因探针,并以此对肝细胞癌中HBV整合及亚基因转录进行了研究,以期为阐明HBV感染后HCC发生机制提供一定的实验资料和依据。本研究中,首先以BamHⅠ、BglⅡ酶切扩增回收的HBVDNA ,回收其HBV亚基因HBx、HBc、HBs、PreSDNA片段,以地高辛甙元随机引物法标记成敏感性与特异性俱佳的HBV亚基因探针,再以HBV探针点杂交检测HCC标本中HBVDNA的阳性率,对阳性的标本,继以Southern转膜杂交检测其整合情况,最后取HBVDNA阳性的HCC标本,按经典方法抽提其mRNA ,分别以HBV亚基因探针Northern转膜杂交检测亚基因的表达率。结果显示:4 4例HCC标本中,75 %的标本显示有HBVDNA的存在;Southern杂交分析,HBV纯整合型HCC为6 3.6 % ,混合型HCC为36 .4 % ,未见单纯游离型HCC标本存在;17例HBVDNA阳性..

第十八届美国理论与应用力学大会总结

1会议概况2018年6月5—9日,第18届美国理论与应用力学大会(18th U.S. National Congress of Theoretical and Applied Mechanics, USNCTAM2018)在美国芝加哥召开.本次大会由美国力学国家委员会和中国力学学会联合主办,旨在探讨和交流近四年世界范围内在理论和应用力学领域的基础研究、创新技术的最新进展,吸引了来自世界各地的近千名专家学

A High Precision Ultrasonic Ranging Method under Misalignment of Transducer Pairs

针对移动机器人超声定位中超声收发传感器角度偏向造成的测距精度下降,本文提出了一种基于归一化波形参数特征修正的超声测距系统.传统的增益控制、可变阈值等抗起伏措施对抑制传播过程中的幅度起伏造成的测距误差效果较好,但如果传感器角度偏向使波形发生畸变,此类方法仍将造成较大误差.本文通过对传感器角度偏向造成接收信号波形畸变及测距精度下降的理论分析及实验研究,建立了超声接收信号归一化波形特征脉宽与前沿变化的关系,设计了基于单片机实现误差校正的大偏向角高精度超声波测距系统.测距实验结果表明本系统显著减小了传感器角度偏向引起的测距误差,在不同的距离上使测距精度平均提高了1.6%,同时具有成本低、使用简单、方便的特点.To tackle the precision degradation caused by misalignment of transducer pairs in mobile robot localization,an adjustment strategy based on normalized waveform parameter is proposed to derive a high precision method for wide-field ultrasonic ranging.Presently most investigation on high precision ultrasonic ranging focused on the amplitude fluctuation induced by random air medium.Nonetheless,previous research indicated that the impact of transducer misalignment on reception signal waveform can be modeled as a low-pass filter,which will cause waveform distortion of reception signal.Thus the performance of traditional approaches to improve the ultrasonic ranging precision such as automatic gain control(AGC) or variable threshold will be seriously affected under misalignment of transducer pairs.In this paper,with theoretical analysis and experimental research on the impacts of transducer misalignment,the relationship between the rising edge and characteristic width of normalized waveform is investigated,which is used to develop an adjustment approach and design a SCM(Single Chip Microcomputer) based high precision wide-field ultrasonic ranging system.The experimental results show this system greatly improves the ranging precision under transducer misalignment,validating the effectiveness and convenience of the proposed scheme.Compared with traditional AGC type method,it improves the ranging precision by about 1.6%.国家自然科学基金(D0602-40476018);; 厦门大学科技创新基金(0050-K70013)资

促控技术对当雄北京杨生长发育及耐寒性影响

以西藏当雄引种北京杨(Populus×beijingensis)1年生扦插苗为实验材料,用复合磷酸二氢钾和多效唑进行交替的促控处理,并在-50～-5℃低温条件下贮藏;通过生长量和生物量测试、物候期比较,评价促控技术对生长发育及耐寒性影响。结果显示:1)当雄北京杨具很强耐寒性;春季根施肥料可明显促进生长和生物量积累;2)秋季每20 d喷施0.1%多效唑明显抑制株高生长、促进生物量积累、改变生物量分配;3)增加多效唑喷施次数能更有效抑制株高生长、促进地径和根系生长及生物量积累,且多效唑对各部位茎段比重的调节效果非常显著;4)秋季施肥不利于生长和生物量积累;5)生长促控措施对植株的物候期调控作用明显,能推迟落叶和萌动期、缩短展叶进程。由此认为:在气候寒冷、生长期短暂的西藏那曲,引进当雄北京杨进行容器育苗生长促控栽培,有利于苗木生长发育和生物量积累,推迟萌动、加速展叶、调节落叶,有效规避低温寒冷造成的伤害,从而加强耐寒性、提高适应能力

带三维凹槽火焰稳定器的燃烧室放热分布规律研究

本文采用数值方法研究了具有三维凹槽的超燃发动机燃烧室燃烧放热分布规律。研究结果表明，受主流超声速流的影响燃烧室内燃烧放热的速率较慢，燃烧室内的总温沿流向逐渐增加，同时伴随着气流总压的严重损失。在较高的进口静温条件下，燃烧室总压损失较小；在较高的燃料注射压力条件下，燃烧室总压损失严重

research on an image deformation algorithm based on calculus and its implementation

图象变形是图象处理中的基本问题,不仅要求图象变形效果好,而且要求变形算法效率高.目前已有的变形算法,大多采用基于象素点的填充方法,这种方法有比较明显的缺点:(1)当变形的图象区域是一个非规则区域时,图象变形处理所花费的时间增加,即算法的时间复杂度加大,效率低;(2)在对象素点作映射变换时,可能出现变形后的图象区域中一个象素点对应变形前的图象区域中多个象素点,因此造成取舍困难,甚至造成取舍错误.为解决这一问题,本文提出了一种基于微分思想的图象变形算法,该算法先将复杂的变形区域划分为一系列子区域,再将每个子