Diversity and distribution of soil micro-fungi along an elevation gradient on the north slope of Changbai Mountain

Elevational changes in patterns of diversity are important to understanding of the influence of global changes, yet few studies have addressed the distribution of microorganisms, e.g. soil micro-fungi. We studied the diversity of the forest soil micro-fungi in four vegetation belts along an elevation gradient on the north slope of Changbai Mountain in Changbai National Nature Reserve. The four belts were characterized as coniferous-deciduous mixed forest, coniferous forest, Erman's birch forest, and alpine tundra. We estimated the quantity and distribution of the fungal species in each belt and calculated three indices, viz. Shannon-Wiener diversity (H'), Pielou's evenness (J'), and Margalef's abundance (E), to depict fungal species diversity. A total of 932 strains were recorded and identified, representing 53 genera, and 108 species. Among these, Penicillium, Aspergillus, Trichoderma, Mucor, Rhizopus and Fusarium were the dominant genera. With increasing elevation, the quantity of fungi and values of H', E, and J' gradually declined.

Vibration and wave propagation analysis of twisted micro-beam using strain gradient theory

In this research, vibration and wave propagation analysis of a twisted micro- beam on Pasternak foundation is investigated. The strain-displacement relations （kine-matic equations） are calculated by the displacement fields of the twisted micro-beam. The strain gradient theory （SGT） is used to implement the size dependent effect at micro-scale. Finally, using an energy method and Hamilton＇s principle, the governing equations of motion for the twisted micro-beam are derived. Natural frequencies and the wave prop- agation speed of the twisted micro-beam are calculated with an analytical method. Also, the natural frequency, the phase speed, the cut-off frequency, and the wave number of the twisted micro-beam are obtained by considering three material length scale parameters, the rate of twist angle, the thickness, the length of twisted micro-beam, and the elastic medium. The results of this work indicate that the phase speed in a twisted micro-beam increases with an increase in the rate of twist angle. Moreover, the wave number is in- versely related with the thickness of micro-beam. Meanwhile, it is directly related to the wave propagation frequency. Increasing the rate of twist angle causes the increase in the natural frequency especially with higher thickness. The effect of the twist angle rate on the group velocity is observed at a lower wave propagation frequency.

Effect of strain-gradients of surface micro-beams on frequency-shift of a quartz crystal resonator under thickness-shear vibrations

With introduction of the first-order strain-gradient of surface micro-beams into the energy density function,we developed a two-dimensional dynamic model for a compound quartz crystal resonator（QCR） system,consisting of a QCR and surface micro-beam arrays.The frequency shift that was induced by micro-beams with consideration of strain-gradients is discussed in detail and some useful results are obtained,which have important significance in resonator design and applications.

5-羟色胺转运蛋白显像剂^(11)C-DASB的自动化合成及Micro PET/CT显像

目的:自动化合成5-羟色胺转运蛋白显像剂11 C-DASB并进行大鼠Micro PET/CT显像;方法:通过改变甲基化试剂、溶解前体溶剂及反应条件,得到优化的标记条件作为碳-11多功能合成模块的输入参数,进行自动化合成11 C-DASB,大鼠静脉注射11 C-DASB 45 min后进行显像;结果:采用11 C-CH3-Triflate作为甲基化试剂,通入新配制的含1mg去甲基DASB前体的500μL DMSO溶液内,80℃下加热2min,标准率为63.7%,大鼠显像表明,11 C-DASB特异性的浓聚于SERT富集区域;结论:经优化,11 C-DASB自动化合成可得到较高产率,大鼠显像表明,其特异性浓聚于SERT富集区域,有望作为5-羟色胺转运蛋白显像剂。

^(18)F-氟赤硝基咪唑micro PET/CT评价裸鼠乳腺癌早期放疗疗效实验研究

目的探讨^(18)F-氟赤硝基咪唑micro PET/CT评价裸鼠MDA-MB231乳腺癌早期放疗疗效的价值。方法建立16只裸鼠MDA-MB231乳腺癌模型,将其按照随机对照原则分为两组:对照组(A组)、放疗组(B组),每组8只。每组裸鼠行micro PET/CT显像,测定每只裸鼠肿瘤SUVmax值。完成显像后,常规HE染色观察每组肿瘤组织形态学特征,免疫组化方法测定每组肿瘤细胞乏氧诱导因子-1α(HIF-1α)的表达情况。结果放疗前,对照组与放疗组SUVmax值差异无统计学意义(t=0. 375,P> 0. 05)。放疗组放疗后48 h裸鼠肿瘤组织SUVmax值较放疗前(t=9. 958,P <0. 05)、放疗后24 h(t=16. 506,P <0. 05)明显降低,差异有统计学意义(F=58. 860,P <0. 05)。放疗后24 h SUVmax值也低于放疗前24 h(t=5. 405,P <0. 05),差异有统计学意义。HE染色结果显示放疗组肿瘤细胞坏死较对照组更加明显。免疫组化结果显示放疗组放疗后HIF-1α表达阳性率明显低于放疗前(t=14. 802,P <0. 05),差异具有统计学意义。相关性分析结果显示肿瘤SUVmax与HIF-1α的表达呈明显正相关性(r=0. 865,P <0. 05)。结论^(18)F-氟赤硝基咪唑micro PET/CT可以监测肿瘤内部的乏氧状态,并且可以评价裸鼠MDA-MB231乳腺癌的早期放疗疗效。

Effect of Heat Treatment on Gradient Microstructure and Tensile Property of Laser Powder Bed Fusion Fabricated 15-5 Precipitation Hardening Stainless Steel

This work investigated the gradient microstructure evolution and tensile property of LPBF fabricated 15-5 precipitation hardening stainless steel in post-process direct ageing(DA)and solution treating&ageing(STA).The varied microstructures for austenite and small-sized oxide inclusions at different sample heights in the as-built(AB)condition was generally preserved after DA treatment.However,austenite was almost disappeared,and oxide particle grew significantly after the STA treatment.As a result,the tensile property differences in sample top and bottom for AB and DA conditions did not occur in the STA samples.For the influence of post-process heat treatment,the STA condition had the highest yield strength due to the highest volume fraction of nano-sized Cu precipitates.However,the DA specimen had the highest ultimate tensile strength and elongation owing to the considerable amount of austenite phase and associated transformation induced plasticity effect.

Shape gradient and classical gradient of curvatures:driving forces on micro/nano curved surfaces

Recent experiments and molecule dynamics simulations have shown that adhesion droplets on conical surfaces may move spontaneously and directionally. Besides, this spontaneous and directional motion is independent of the hydrophilicity and hydrophobicity of the conical surfaces. Aimed at this important phenomenon, a gen- eral theoretical explanation is provided from the viewpoint of the geometrization of micro/nano mechanics on curved surfaces. In the extrinsic mechanics on micro/nano soft curved surfaces, we disclose that the curvatures and their extrinsic gradients form the driving forces on the curved spaces. This paper focuses on the intrinsic mechanics on micro/nano hard curved surfaces and the experiment on the spontaneous and directional motion. Based on the pair potentials of particles, the interactions between an isolated particle and a micro/nano hard curved surface are studied, and the geometric foundation for the interactions between the particle and the hard curved surface is analyzed. The following results are derived： （a） Whatever the exponents in the pair potentials may be, the potential of the particle/hard curved surface is always of the unified curvature form, i.e., the potential is always a unified function of the mean curvature and the Gaussian curvature of the curved surface. （b） On the basis of the curvature-based potential, the geometrization of the micro/nano mechanics on hard curved surfaces may be realized. （c） Similar to the extrinsic mechanics on micro/nano soft curved surfaces, in the intrinsic mechanics on micro/nano hard curved surfaces, the curvatures and their intrinsic gradi- ents form the driving forces on the curved spaces. In other words, either on soft curved surfaces or hard curved surfaces and either in the extrinsic mechanics or the intrinsic mechanics, the curvatures and their gradients are all essential factors for the driving forces on the curved spaces. （d） The direction of the driving force induced by the hard curved surface is independent of the hydrophilieity and hydrophobicity of the curved surface, explaining the experimental phenomenon of the spontaneous and directional motion.

Micro-Scanning Error Correction Technique for an Optical Micro-Scanning Thermal Microscope Imaging System

An error correction technique for the micro-scanning instrument of the optical micro-scanning thermal microscope imaging system is proposed. The technique is based on micro-scanning technology combined with the proposed second-order oversampling reconstruction algorithm and local gradient image reconstruction algorithm. In this paper, we describe the local gradient image reconstruction model, the error correction technique, down-sampling model and the error correction principle. In this paper, we use a Lena original image and four low-resolution images obtained from the standard half-pixel displacement to simulate and verify the effectiveness of the proposed technique. In order to verify the effectiveness of the proposed technique, two groups of low-resolution thermal microscope images are collected by the actual thermal microscope imaging system for experimental study. Simulations and experiments show that the proposed technique can reduce the optical micro-scanning errors, improve the imaging effect of the system and improve the system's spatial resolution. It can be applied to other electro-optical imaging systems to improve their resolution.

Effect of Surface Roughness in Micro-nano Scale on Slotted Waveguide Arrays in Ku-band

Modeling of the roughness in micro-nano scale and its influence have not been fully investigated, however the roughness will cause amplitude and phase errors of the radiating slot, and decrease the precision and efficiency of the SWA in Ku-band. Firstly, the roughness is simulated using the electromechanical coupled（EC） model. The relationship between roughness and the antenna＇s radiation properties is obtained. For verification, an antenna proto- type is manufactured and tested, and the simulation method is introduced. According to the prototype, a contrasting experiment dealing with the flatness of the radiating plane is conducted to test the simulation method. The advantage of the EC model is validated by comparisons of the EC model and two classical roughness models （sine wave and fractal function）, which shows that the EC model gives a more accurate description model for roughness, the maxi- mum error is 13%. The existence of roughness strongly broadens the beamwidth and raises the side-lobe level of SWA, which is 1.2 times greater than the ideal antenna. In addition, effect of the EC model＇s evaluation indices is investigated, the most affected scale of the roughness is found, which is 1/10 of the working wavelength. The proposed research provides the instruction for antenna designing and manufacturing.

Signal Efficiency in Gradient Index Lens Based Two Photon Microscopy

Gradient index (GRIN) lenses are often used as an optical relay to a sample at a location that is not accessible for a standard microscope. This capability is turning them into an important enabling technology that extends many optical imaging modalities like harmonic laser scanned imaging with micro endoscopic in vivo capabilities as needed in research and diagnostics. These micro endoscopic imaging variants however rely on the light scattering capability of the underlying tissue. Further complications arise from an increased number of optical interfaces and the overall optical performance of a GRIN rod. We have therefore performed a quantitative comparison of the back-scattered second harmonic generation (SHG) signal intensity generated in skin and low-scattering muscle tissue, both obtained with a standard two photon laser scanning microscope (LSM) and a GRIN lens based LSM. We report that the GRIN lens based system sees approximately 1/4 of the net two photon signal detected by the standard LSM. We expect that this value can be generalized to other LSM techniques enhanced by GRIN technology and encourage its use in experimental situations with standard LSM signal to noise ratios of four or higher.

适宜水工混凝土内环境的矿化微生物梯度驯化优选

水工混凝土内部高碱性环境限制了微生物混凝土的自修复效能。利用梯度驯化方法可提高矿化微生物对高碱度的耐受性,优选出适宜混凝土孔隙内环境并具备高诱导矿化沉积能力的增强嗜碱型微生物。首先,在实验室高碱性环境下,对比巨大、科氏、枯草、巴氏等4种芽孢杆菌的活性及诱导矿化沉积量,初选耐碱性较好的微生物并对其开展耐碱性梯度驯化;随后,综合分析驯化微生物对混凝土力学性能、吸水性、渗透性和自愈能力的影响,通过扫描电子显微镜和X射线衍射对矿化产物微观形态和组成进行分析。结果表明:相较于巨大、科氏和枯草芽孢杆菌,巴氏芽孢杆菌在高碱性条件下表现出更强的活性,梯度驯化技术可进一步提高巴氏芽孢杆菌在高碱性环境中的活性,并证实通过该方法增强的耐碱性具有后代保留的特性;与掺未驯化微生物组试样相比,掺驯化微生物混凝土试样养护28 d的抗压强度提高了16.59%,吸水系数降低了37.74%,渗透系数减小了19.22%;掺驯化微生物混凝土试样的裂缝自修复试验得到裂缝最大修复宽度为0.57 mm,超过了未驯化微生物组的0.44 mm。本研究为基于微生物诱导矿化沉积技术的微生物水工混凝土研发和应用提供理论依据和技术支撑。

PCR-DGGE技术及其在植物微生态研究中的应用

植物中微生物种类较为丰富,在植物微生态系统中发挥重要作用。变性梯度凝胶电泳(denaturinggradient gel electrophoresis,DGGE)技术作为研究微生物物种多样性和种群动态变化的分子检测工具之一,广泛应用于植物微生物群落多样性和群落动态变化研究中。概述了DGGE技术的原理,及其在植物微生物生态学中的应用以及在该领域研究中导致DGGE偏差的因素和相应解决方法,对DGGE检测结果的分析提供参考,为进一步研究植物微生物相互作用提供帮助。

Mn含量对梯度多孔Mg-Mn合金微弧氧化膜组织与性能的影响

研究了Mn含量对梯度多孔Mg-Mn合金微弧氧化过程中电压-时间曲线、微弧氧化膜层显微组织、膜层厚度、物相组成以及耐腐蚀性能的影响。结果表明,随Mn元素含量的增加,微弧氧化电压-时间曲线中的起始电压U1、击穿电压U2和稳定电压U3均下降,但是当Mn含量超过2%后,U1、U2、U3均上升,随着Mn元素含量的增加,微弧氧化膜层厚度先降低而后增加。当Mn含量为2%时,梯度多孔Mg-Mn合金表面形成的氧化膜质量最好,孔隙细小、分布均匀,膜层厚度为39.6μm。结合XRD和EDS分析表明,微弧氧化处理后试样表面膜层由Mg2Si O4和Mg O两相组成。随着在模拟体液中浸泡时间的延长,添加2%Mn元素的梯度多孔Mg-Mn合金的质量损失最少,析氢量最低,耐腐蚀性最佳。

犬累-卡-佩斯病的组织形态学观察

本试验旨在对临床上患累-卡-佩斯病犬的股骨头组织形态学进行观察,对该病的组织病理学变化进行描述。收集中国农业大学动物医院患有累-卡-佩斯病并采取手术切除治疗的犬的股骨头以及正常犬的股骨头,对其进行大体观察,Micro-CT观察股骨头三维微观结构,取股骨头负重区组织进行H.E.染色、甲苯胺蓝染色观察病理变化,扫描电镜观察各组股骨头骨显微结构变化。结果显示,病变组较正常组股骨头结构破坏严重,组织结构疏松、易于凿切,髓腔脂肪细胞增大增多,骨小梁在塌陷、溶解的同时,伴有新小梁骨的形成。

台阶开孔式缓冲结构对隧道气动效应分析

随着列车速度的不断提升,列车由明线驶入隧道所引发的微气压波问题变得日益突出,组合型式缓冲结构较单一型式缓冲结构能更好的缓解微气压波的影响,为了进一步减缓微气压波对隧道周边环境的影响,提出了台阶开孔式组合型缓冲结构。基于κ-ε两方程紊流模型(κ为湍动能,ε为耗散率),运用数值模拟的方法,从开孔距离、开孔率、开孔数量、开孔位置4个方面进行研究,对列车驶入隧道所引起的初始压缩波压力和压力梯度值进行具体分析,得出优化设计参数。台阶开孔式缓冲结构对初始压缩波压力最大值的影响较小,但对初始压缩波压力梯度值影响较大。当开孔距离为4 m、开孔率α为36%、开孔数量为2孔、开孔位置为顶部开孔时,为最优工况,对压力梯度的减缓效果达到了60.14%。

PCR-DGGE分析技术在环境检测中的应用

多聚酶链式反应结合变性梯度凝胶电泳（PCR-DGGE）分析技术是一项基于分子生物学技术的分析方法。文章综述了PCR—DGGE分析技术的产生背景、基本原理和在环境微生物检测中的应用现状，并对该技术的优缺点和今后的应用前景进行了探讨。

miRNA-9过表达对Aβ损伤的PC12细胞的保护作用

目的:探讨micro RNA-9(mi R-9)过表达对β-淀粉样蛋白(Aβ)损伤的PC12细胞及B淋巴细胞瘤-2(Bcl-2)、Bcl-2相关x蛋白(Bax)表达的影响。方法:PC12细胞分为mi R-9过表达组(E组)、空转染对照组(NC组)、不转染的损伤细胞模型组(NT组),采用CCK-8法检测细胞增殖;采用Annexin-V-PE检测细胞凋亡;采用RT-q PCR检测Bcl-2、Bax m RNA的表达,Western-Blot检测Bcl-2、Bax蛋白表达。结果:与NC组及NT组比较,E组的PC12细胞转染48 h后增殖增加,凋亡率降低,Bcl-2表达增加,Bax表达下降(P<0.05)。结论:mi R-9过表达可保护Aβ损伤的PC12细胞。

miR-582-5p在唾液腺腺样囊性癌侵袭、转移中的作用

目的 :探讨micro RNA-582-5p(miR-582-5p)对唾液腺腺样囊性癌侵袭、转移能力的调控作用。方法 :通过q PCR验证腮腺腺样囊性癌与正常组织中miR-582-5p的表达水平差异,以唾液腺腺样囊性癌肺转移细胞株SACC-83为实验对象,通过脂质体介导,将miR-582-5p的拟似物(miR-582-5p mimics)转染至SACC-83细胞,升高miR-582-5p的表达水平。采用荧光实时定量PCR(RT-PCR)检测转染前、后SACC-83中miR-582-5p的表达变化,通过Transwell实验检测细胞侵袭、迁移能力的改变,通过荧光素酶报告实验验证靶基因,Western印迹检测miR-582-5p的靶基因整合素FOXC1的表达变化,免疫组织化学检测FOXC1在癌与正常组织中的差异表达,应用SPSS 16.0软件包对所得数据进行t检验或单因素方差分析。结果:miR-582-5p在唾液腺腺样囊性癌组织中低表达,在正常组织中高表达。转染miR-582-5p mimics后的SACC-83中,miR-582-5p的表达显著上调(P<0.001),SACC-83细胞的侵袭迁移能力显著降低(P<0.001)。Western印迹检测结果显示,在SACC-83中升高miR-582-5p的表达水平后,FOXC1表达显著降低。FOXC1在唾液腺腺样囊性癌组织中高表达,在正常组织中低表达。结论 :低表达miR-582-5p有助于维持腺样囊性癌的侵袭、转移特性;调高其表达水平,能有效抑制SACC-83的侵袭、迁移能力。miR-582-5p可能通过调控其靶基因FOXC1的表达而发挥作用。

SSS-Ⅱ高梯度磁选机回收微细粒钛铁矿的研究

介绍了新型SSS-Ⅱ磁选机的分选原理.通过考查粒级回收率的方法,对SSS-Ⅱ型高梯度磁选机和常规高梯度磁选机精矿产品的各粒级回收率进行了分析.结果表明,SSS-Ⅱ型高梯度磁选机对-0.020mm的高效回收是其分选指标较常规高梯度磁选机好的原因之一.

微纳米空间弯曲诱导的反常驱动力--从泡利的魔鬼谈起

介绍了高度卷曲的微纳米物质空间诱发的反常驱动力,指出构成反常驱动力的基本要素有两个:一个是空间的弯曲程度,即曲率,另一个是空间弯曲的不均匀程度,即曲率的梯度.