基于磁驱动技术的空肠营养管的设计

目的:为解决目前床旁鼻肠管快速置入成功率低这一临床难题,该文提出一种基于磁驱动技术的空肠营养管的设计。方法:分析了现有空肠营养管置管过程中的动力因素,结合磁驱动技术原理,提出了通过体外旋转磁场带动体内感应磁体螺旋式前进的设计方案,以期缩短空肠营养管的飘管时间。结果:该设计包括磁性空肠营养管和体外磁力驱动装置两部分。其中磁性空肠营养管由管体和感应磁头两部分构成,感应磁头包括磁体内核和硅胶外壳。磁力驱动装置由多极磁体和手持式微型电机组成。操作时通过体外磁力驱动装置发出大旋转磁场带动空肠营养管的感应磁头做轴向旋转运动,可加速空肠营养管在肠道内的移动,达到缩短飘管时间的目的。结论:该设计基于磁驱动技术原理,设计巧妙,符合磁力学原理,操作简单,具有临床应用潜力。     

适用于磁压榨吻合的平移钳的设计

目的:提出了磁压榨吻合操作中可用于磁体夹持固定的平移钳的结构设计方案。方法:分析本团队多种原创性磁压榨吻合技术操作中存在的缺陷和不足,认为目前磁压榨吻合操作中依靠术者徒手控制或利用现有血管钳对磁体进行夹持和固定,是造成操作中诸多不便的主要原因。从力学角度分析了常规血管钳夹持磁体易导致磁体滑脱的原因,指出设计加工磁吻合专用钳是解决目前磁吻合操作不便的有效措施。在此基础上提出了利用平移钳来固定磁体的结构设计方案,并从力学角度进行了受力分析,设计出了用于磁压榨吻合操作中磁体夹持固定的平移钳。结果:平移钳的结构设计能够稳定夹持磁体,避免磁体滑脱;同时,借助齿轮传动结构控制钳头的平行移动能够更好地控制磁体的精准对吸和分离,可进一步简化操作,避免副损伤,节省手术操作时间。结论:平移钳能满足多种形状及大小的磁体的夹持和固定,可有效控制磁体的吸合与分离,极大地方便操作。该平移钳加工简单,使用方便,有助于推动磁压榨吻合技术在临床广泛开展。     

趋磁细菌及其应用于生物导航的研究进展

趋磁性细菌是一种由于体内含有对磁场具有敏感性的磁小体,而能够沿着磁力线运动的特殊细菌,本文综述了趋磁细菌的分布、分类、特性、磁小体研究以及趋磁细菌在生物导航方面的研究进展。     

磁压榨技术建立大鼠胃肠吻合模型的实验研究

目的:探讨采用磁压榨技术建立大鼠胃肠吻合模型的可行性。方法:设计加工适用于大鼠胃肠吻合的子、母磁体。将10只SD大鼠采用磁压榨技术进行胃肠吻合,子、母磁体分别经口置入大鼠胃和空肠内,子母磁体相吸压榨胃壁和肠壁,磁体间受压组织缺血坏死后连同磁体从吻合口脱落入肠道,胃肠吻合即建立,磁体最终经消化道自行排出体外,术后2周处死动物,获取吻合口标本,检测吻合口爆破压、肉眼和光镜下观察吻合口愈合情况。结果:10只SD大鼠中,1只因麻醉意外死亡,其余9只大鼠均顺利完成手术操作并存活至术后2周;手术平均操作时间(15.89±3.25)min,磁体排出体外时间(8.56±1.26)天(范围7-11)天;吻合口爆破压均大于200 mm Hg,吻合口组织HE染色和Masson染色可见粘膜层连续性建立,愈合良好。结论:磁压榨技术可用于大鼠胃肠吻合模型制备,具有操作简单、成功率高的优点。     

磁细菌和细菌磁的研究进展

磁细菌具有磁性趋向性,可沿地球磁场磁力线向磁极移动,甚至在磁力较弱的地域也是如此.Blakemore (1975)首先进行了描述,他们分布广泛,主要存在于海水,淡水的生物沉积物中.磁细菌能够合成胞内磁铁颗粒(Fe_3O_4),因而具有磁性趋向性.这些磁粒在50～100nm的特定范围内为膜所包围,10～20个颗粒相连成线状,构成细菌磁.许多研究者已成功研制了生产细菌磁的机械装置,但到目前为止,还设有细菌磁直接应用的报道.     

细菌磁的生物技术开发和利用

细菌磁的生物技术开发和利用任修海（上海大学生物工程系,上海２０１８００）磁细菌即向磁性细菌沿地球磁力线移动,其细菌内含有自身合成的生物磁颗粒,这些颗粒细小均匀,外被生物膜,呈链状排列。最近在磁细菌的分离及培养技术上获得许多进展,为细菌磁的大规模生产奠...     

固体平板磁泳分离细菌新方法的研究

氧化亚铁硫杆菌（Acidithiobacillus ferrooxidans）能够在胞内形成电子致密的磁性颗粒,它的这种特性使利用氧化亚铁硫杆菌合成生物纳米磁性材料成为了可能。本课题组为了筛选出合成磁性颗粒能力强的菌株,对原有的液体磁泳进行了改进,采用了新的固体平板磁泳方法来筛选纯化目的菌株。经过磁泳分离后,细菌中含磁性颗粒的细胞比例由原始菌群的30％上升到90％,胞内含有的磁颗粒数目也由1~2颗增加至2~5颗,筛选得到的细菌在人工磁场下会进行趋磁运动。实验结果表明,氧化亚铁硫杆菌具有较弱的趋磁性,在人工磁场下会进行趋磁运动,但仅在地磁场作用下不能定向运动,利用固体平板磁泳筛选纯化含有磁性颗粒的氧化亚铁硫杆菌的方法是切实可行的,磁泳分离技术的进一步完善和改进为传统的微生物菌种分离提供了新的途径,为研究纯氧化亚铁硫杆菌菌株胞内磁性颗粒的形成条件及机理提供了前提条件,也为今后从浸矿细菌中分离筛选更多的含有磁性颗粒的菌株打下基础。     

红条毛肤石鳖齿舌牙齿内Fe3O4的研究

目的:探讨红条毛肤石鳖齿舌牙齿内磁性纳米物质(Fe3O4)的晶体结构、磁畴及磁晶各向异性等磁学性质.方法:从红条毛肤石鳖齿舌主要横向牙齿中提取出磁性纳米磁性矿物质(Fe3O4),用高分辨透射电子显微镜,扫描电子显微镜研究其外貌及晶体结构,用磁力显微镜观察其磁畴结构,然后利用超导量子干涉磁强计(SQUID)和磁转矩测量仪测量其磁化曲线,探讨它的磁各向异性.结果:①红条毛肤石鳖齿舌中的磁铁矿为长约几微米、宽约100纳米的长条片壮物质,由尺度约为50纳米的磁铁矿小晶粒及有机物质构成.②小晶粒的[111]方向沿着长条片状物质的长度方向,具有沿着厚度方向的单磁畴结构.③SQUID和磁转矩测量均证明长条片状纳米磁性矿物质的长度方向为易磁化方向.红条毛肤石鳖齿舌中的磁性矿物质与自然界中的磁铁矿具有相同的结构.结论:红条毛肤石鳖齿舌中的磁性物质为具有单畴结构、易磁化方向为[111]方向的Fe3O4晶体.     

Nigeiqianlm胃镜引导下放置十二指肠营养管治疗食管癌术后吻合口瘘的临床效果及应用体会

目的:探讨胃镜引导下置入十二指肠营养管治疗食管癌术后并发吻合口瘘的临床效果及其应用体会。方法:在2008年1月至2011年9月入我科治疗的3126例食管癌手术患者中,49例术后并发吻合口瘘,患者经胃镜引导下置营养管于十二指肠降部,给予肠内营养治疗。术前1天、术后第5天、第7天、出院时分别测定患者体重,术后第1天起逐日观察患者肛门排气、排便等胃肠功能恢复情况。结果:49例患者中首次置管成功47例,成功率96%,置管时间10～20min,平均12min,置管及术后未发生严重并发症;鼻肠营养管肠内营养术后第7天体重下降≤2kg;肠道功能恢复快,术后肛门排气时间≤3d。结论:置入营养管的长度要较胃镜观察长约20cm并妥善固定可提高首次置管成功率。胃镜引导下置入十二指肠营养管对食管癌术后并发吻合口瘘的患者是一种安全、方便、有效的肠内营养途径,对此类患者的营养治疗起重要支持作用,具有临床应用价值。     

磁泳分离细菌新方法的研究

从酸性矿坑水中富集培养分离到的嗜酸氧化亚铁硫杆菌（Acidithiobacillus ferrooxidans,A.ferrooxidans）[1-2] 菌同趋磁细菌具有一定的相似性。通过显微镜观察发现,部分浸矿细菌在外加磁场的作用下具有微弱的趋磁性,基于菌种的这种特性,设计了磁泳分离仪,对其在磁场作用下泳动（磁泳）进行分析,经磁泳后的近磁、远磁菌的生理特性有较大的差异。从用涂布平板法获得的近磁菌纯培养A. ferrooxidans菌体中,分离得到纳米磁性颗粒,能谱分析表明,其主要成分为Fe和O元素。实验结果证明,A. ferrooxidans具有微弱趋磁性,采用磁泳分离该类菌体内含有磁性颗粒的细菌是可行的,这一分离技术的进一步完善和改进将为传统的微生物菌种分离提供一种新型分离技术,也将大大促进趋磁细菌的研究,而且它与浸矿工艺的结合将大大促进我国生物冶金的研究步伐。     

Towards MR-guided electron therapy: Measurement and simulation of clinical electron beams in magnetic fields

PurposeIn the current era of MRI-linac radiotherapy, dose optimization with arbitrary dose distributions is a reality. For the first time, we present new and targeted experiments and modeling to aid in evaluating the potential dose improvements offered with an electron beam mode during MRI-linac radiotherapy.MethodsSmall collimated (1 cm diameter and 1.5 × 1.5 cm² square) electron beams (6, 12 and 20 MeV) from a clinical linear accelerator (Varian Clinac 2100C) are incident perpendicular and parallel to the strong and localized magnetic fields (0–0.7 T) generated by a permanent magnet device. Gafchromic EBT3 film is placed inside a slab phantom to measure two-dimensional dose distributions. A benchmarked and comprehensive Monte Carlo model (Geant4) is established to directly compare with experiments.ResultsWith perpendicular fields a 5% narrowing of the beam FWHM and a 10 mm reduction in the 15% isodose penetration is seen for the 20 MeV beam. In the inline setup the penumbral width is reduced by up to 20%, and a local central dose enhancement of 100% is observed. Monte Carlo simulations are in agreement with the measured dose distributions (2% or 2 mm).ConclusionA new range of experiments have been performed to offer insight into how an electron beam mode could offer additional choices in MRI-linac radiotherapy. The work extends on historic studies to bring a successful unified experimental and Monte Carlo modeling approach for studying small field electron beam dosimetry inside magnetic fields. The results suggest further work, particularly on the inline magnetic field scenario.     

Cytological and anatomical observations on the awn and lemma of wheat (Triticum aestivum L. cv. Ofanto)

Abstract

The anatomy and cytology of the awn and lemma of Triticum aestivum cv. Ofanto was studied. Transverse sections of awns showed five vascular bundles, elongated and branched chlorenchyma cells containing protein bodies are lacking in starch; therefore sugars are supposed rapidly translocated. Starch is abundant in the spike. Phytoliths are present.     

A semi-analytical model for calculating the penetration depth of a high energy electron beam in a water phantom with a magnetic field

PurposeAs an electron beam is incident on a uniform water phantom in the presence of a lateral magnetic field, the depth-dose distribution of the electron beam changes significantly and forms the well-known ‘Bragg peak’, with a depth-dose distribution similar to that of heavy ions. This phenomenon has pioneered a new field in the clinical application of electron beams. For such clinical applications, evaluating the penetration depth of electron beams quickly and accurately is the critical problem.MethodsThis paper describes a model for calculating the penetration depth of an electron beam rapidly and correctly in a water phantom under the influence of a magnetic field. The model was used to calculate the penetration depths under different conditions: the energies of electron beams of 6, 8, 12 and 15 MeV and the magnetic induction intensities of 0.75, 1.0, 1.5, 2.0 and 3.0 T. In addition, the calculation results were compared with the results of a Monte Carlo simulation.ResultsThe comparison results indicate that the difference between the two calculation methods was less than 0.5 cm. Moreover, the computing time of the calculation model was less than a second.ConclusionsThe semi-analytical model proposed in the present study enables the penetration depth of the electron beam in the presence of a magnetic field to be obtained with a computational efficiency higher than that of the Monte Carlo approach; thus, the proposed model has high potential for application.     

野生和人工饲喂条件下甘肃鼢鼠肠道细菌多样性比较

[目的] 肠道微生物在宿主代谢和健康方面发挥着重要的作用,已有报道表明甘肃鼢鼠肠道菌群和地域、性别以及季节等因素有关,但对于野生和人工饲喂条件下,取食不同食物的甘肃鼢鼠肠道菌群是否存在差异尚不明确。[方法] 本研究选取苜蓿、樟子松根、油松根和云杉根对甘肃鼢鼠进行分组饲喂,同时以野生个体作为对照,采用16S rRNA V3-V4高通量测序技术对野生和人工饲喂甘肃鼢鼠肠道细菌进行比较。[结果] 野生和人工饲喂条件下,优势菌门均为Firmicutes和Bacteroidetes,但含量却存在显著性差异。在人工饲喂条件下,樟子松根、油松根和云杉根饲喂的三组甘肃鼢鼠肠道细菌群落结构相似度较高,而与苜蓿组和野生组之间均存在较大差异,樟子松组、油松组和云杉组甘肃鼢鼠肠道细菌多样性高于苜蓿组和野生组。[结论] 野生和人工饲喂条件下甘肃鼢鼠肠道菌群组成和结构存在显著性差异。     

口腔种植的新型钛材料生物安全性研究

目的:在动物体内进行新型钛材料的生物安全性研究。方法:采用TAI纯钛板材(Ti≥99.9%,宝鸡英耐特有色金属有限公司),通过对钛材料的喷砂、酸蚀、碱热等处理后,构建微纳双级骨仿生结构。对处理材料进行扫描电镜观察后,再经过兔皮下实验、小鼠急性溶血性实验确定此种材料的体内安全性。结果:1.扫描电镜结果显示:经过喷砂酸蚀碱热处理后的实验组具有微纳复合结构,与骨组织表面形态更为接近,从仿生学出发,更利于骨组织愈合与抑制骨组织周围炎的发生。2.皮下植入实验结果:经过喷砂酸蚀碱热处理后的实验组与只经过喷砂酸蚀的对照组对生物组织无明显刺激,未见明显的周围组织炎。3.急性毒性实验:未见经过喷砂酸蚀碱热处理后的实验组与只经过喷砂酸蚀的对照组出现明显的生物学反应,未见明显体重下降。结论:新型表面处理钛材料在生物安全性的动物体外实验方面无异常,可以进行下一步实验。     

The Effect of Heat Stress on Wheat Leaf and Ear Photosynthesis

The effect of heat-hardening on carbon exchange rate per unitarea (CER) of flag leaves, whole ears, and ears with the awnsremoved, was measured in hexaploid (Triticum aestivum L.) andtetraploid (T. turgidum L. and T. dicoccoides) wheat varieties.The CER for awns was calculated by the difference. For the non-hardened hexaploid cv. ‘H-895’ the CERfor the leaves and glumes had an optimum temperature of 25°C.By contrast, the CER for the awns increased from 25°C to32°C, indicating an optimum at 32°C or more. Heat-hardeningdecreased the CER of leaves and glumes at the optimum temperature,but increased the CER especially in leaves at supra-optimaltemperatures. Thus, leaf CER in hardened plants became essentiallyindependent of temperatures between 25°C and 32°C. AwnCER was little affected by heat-hardening. For all 12 varieties, leaf and ear CER was smaller in hardenedplants at 30°C than in non-hardened plants at 22°C.Leaf and ear CER measured at 30°C differed significantlybetween varieties within a species. Whole ear CER at 30°Cwas negative in most varieties although the calculated valuefor the awns was positive. Thus, the high temperature optimumfor CER of the awns was a major factor in the variation amongwheat varieties in tolerance of ear CER to heat. The biochemicalattributes of the photosynthetic mechanism in awns responsiblefor the high temperature optimum were already present in wildtetraploid wheat. There was a positive correlation across allvarieties between ear CER at 30°C and the percentage ofawns in total ear area (r = 0930, P = 0 This together with previousresults (Blum, 1985a), suggests that a large amount of awnsin the ear is a sensible selection index in wheat for improvedproduction in hot, dry environments. Key words: Carbon exchange rate, photosynthesis, awns, heat, stress, wheat, breeding     

Photosynthesis and Transpiration in Leaves and Ears of Wheat and Barley Varieties

Carbon exchange rate (CER) and transpiration were measured inflag leaves, whole ears, glumes (referring to the total areaof glumes and lemmas) and awns, in six hexaploid spring wheats(Triticum aestivum L.), three cultivated tetraploid spring wheats(T. turgidum L.), four wild tetraploid wheats (T. dicoccoides),eight six-rowed barleys (Hordeum vulgare L.) and five two-rowedbarleys (H. vulgare L.). Differences between varieties and between species in total earCER and transpiration were associated largely with differencesin ear surface area rather than with rates per unit area. Ratesof CER and transpiration per unit area of ears were 40–80%of those of flag leaves, depending on the species. However, since ear surface area was greater than flag leaf areaby a factor of 1.1, 3.9, 5.5 and 4.4, in hexaploid wheat, tetraploidwheat, six-rowed barley, and two-rowed barley, respectively,total ear CER reached up to 90% of that of the flag leaf. The contribution of awns to total ear CER depended largely ontotal awn surface area per ear, rather than on CER per unitawn area. Awns contributed about 40–80% of total spikeCER, depending on the species, but only 10–20% of spiketranspiration. The disproportionately small contribution ofawns to ear transpiration was caused by the very low rate oftranspiration per unit area of awns. Thus, while transpirationratio (CER/transpiration) was about the same in flag leavesand glumes, it was higher by several orders of magnitude inthe awns. A large amount of awns in the ear is therefore a drought adaptiveattribute in these cereals, for which tetraploid wheat exceededhexaploid wheat and six-rowed barley exceeded two-rowed barley. Key words: Carbon exchange rate, Transpiration, Barley, Wheat