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Bench-top aqueous two-phase extraction of isolated individual single-walled carbon nanotubes

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Nano Research 2015年第5期8卷 1755-1769页

作者： Navaneetha K. Subbaiyan A. Nicholas G. Parra-Vasquezt Sofie Cambre Miguel A. Santiago Cordoba Sibel Ebru Yalcin Christopher E. Hamilton nathan H. Mack Jeffrey l. Blackburn Stephen K. Doorn Juan G. Duque Chemistry Division Physical Chemistry and Applied Spectroscopy Group (C-PCS) Center for Integrated Nanotechnologies (CINT) and Materials Science & Technology Division (MST-7) Los Alamos National Laboratory Los Alamos New Mexico 87544 USA Experimental Condensed Matter Physics laboratory University of Antwerp Antwerp B-2610 Belgium National Renewable Energy laboratory Golden Colorado 80401 USA

Isolation and purification of single-walled carbon nanotubes （SWCNTs） are prerequisites for their implementation in various applications. In this work, we present a fast （-5 min）, low-cost, and easily scalable bench-top approach to the extraction of high-quality isolated SWCNTs from bundles and impurities in an aqueous dispersion. The extraction procedure, based on aqueous two-phase （ATP） separation, is widely applicable to any SWCNT source （tested on samples up to 1.7 nm in diameter） and independent of defect density, purity, diameter, and length. The extracted dispersions demonstrate that the removal of large aggregates, small bundles, and impurities is comparable to that by density gradient ultracentrifugation, but without the need for high-end instrumentation. Raman and fluorescence-excitation spectroscopy, single-nanotube fluorescence imaging, atomic force and transmission electron microscopy, and thermogravimetric analysis all confirm the high purity of the isolated SWCNTs. By predispersing the SWCNTs without sonication （only gentle stirring）, full-length, pristine SWCNTs can be isolated （tested up to 20 μm）. Hence, this simple ATP method will find immediate application in the generation of SWCNT materials for all levels of nanotube research and applications, from fundamental studies to high-performance devices.

关键词： carbon nanotubes aqueous two-phase (ATP)separation aggregate removal isolation sorting

The AFB1 auxin receptor controls the cytoplasmic auxin response pathway in Arabidopsis thaliana

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Molecular Plant 2023年第7期16卷 1120-1130页

作者： Shiv Mani Dubey Soeun Han nathan Stutzman Michael J.Prigge Eva Medvecka Matthieu Pierre Platre Wolfgang Busch Matyas Fendrych Mark Estelle Department of Experimental Plant Biology Faculty of SciencesCharles UniversityPragueCzech Republic Section of Cell and Developmental Biology University of California San DiegoLa JollaCAUSA Plant Molecular and Cellular Biology laboratory and Integrative Biology laboratory Salk Institute for Biological StudiesLa JollaCAUSA Department of Biology Chungbuk National UniversityCheongjuKorea

The phytohormone auxin triggers root growth inhibition within seconds via a *** members of the TIR1/AFB auxin receptor family,AFB1 has a primary role in this rapidresponse. However, the unique features that confer this specific function have not been *** we show that the N-terminal region of AFB1, including the F-box domain and residues thatcontribute to auxin binding,is essential and sufficient for its specific role in the rapid response. Substitutionof the N-terminal region of AFB1 with that of TIR1 disrupts its distinct cytoplasm-enriched localizationand activity in rapid root growth inhibition by auxin. Importantly, the N-terminal region of AFB1 isindispensable for auxin-triggered calcium influx, which is a prerequisite for rapid root growth ***, AFB1 negatively regulates lateral root formation and transcription of auxin-induced genes,suggesting that it plays an inhibitory role in canonical auxin signaling. These results suggest that AFB1may buffer the transcriptional auxin response, whereas it regulates rapid changes in cell growth thatcontributeto rootgravitropism.

关键词： gravitropism calcium auxin signaling Arabidopsis lateral root

Exploiting rotational asymmetry for sub-50 nm mechanical nanocalligraphy

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Microsystems & Nanoengineering 2021年第5期7卷 61-68页

作者： Nikolaos Farmakidis Jacob l.Swett nathan Youngblood Xuan li Charalambos Evangeli Samarth Aggarwal Jan A.Mol Harish Bhaskaran Department of Materials University of OxfordParks RoadOxford 0X13PHUK Department of Physics Queen Mary University of LondonLondon El 4NSUK

Nanofabrication has experienced extraordinary progress in the area of lithography-led processes over the last decades,although versatile and adaptable techniques addressing a wide spectrum of materials are still *** probe lithography(SPl)offers the capability to readily pattern sub-100 nm structures on many surfaces;however,the technique does not scale to dense and multi-lengthscale ***,we demonstrate a technique,which we term nanocalligraphy scanning probe lithography(nc-SPl),that overcomes these ***-SPl employs an asymmetric tip and exploits its rotational asymmetry to generate structures spanning the micron to nanometer lengthscales through real-time linewidth *** specialized tip geometries and by precisely controlling the patterning direction,we demonstrate sub-50 nm patterns while simultaneously improving on throughput,tip longevity,and reliability compared to conventional SPl We further show that nc-SPl can be employed in both positive and negative tone patterning modes,in contrast to conventional *** underlines the potential of this technique for processing sensitive surfaces such as 2D materials,which are prone to tip-induced shear or beam-induced damage.

关键词： lithography tuning versatile

Helical Covalent Polymers with Unidirectional Ion Channels as Single lithium-Ion Conducting Electrolytes

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CCS Chemistry 2021年第12期3卷 2762-2770页

作者： Yiming Hu nathan Dunlap Hai long Hongxuan Chen lacey J.Wayment Michael Ortiz Yinghua Jin Abdulrahiman Nijamudheen Jose l.Mendoza-Cortes Se-hee lee Wei Zhang Department of Chemistry University of Colorado BoulderBoulderCO 80309 Department of Mechanical Engineering University of Colorado BoulderBoulderCO 80309 National Renewable Energy laboratory GoldenCO 80401 Department of Chemical Engineering and Materials Science Michigan State UniversityEast LansingMI 48824

Single-ion conducting polymer electrolytes have attracted great attention as safe alternatives to liquid electrolytes in high energy density lithium-ion ***,we report the first example of a crystalline anionic helical polymer as a single lithium-ion conducting solid polymer electrolyte(SPE).Single-crystal X-ray analysis shows that the polymer folds into densely packed double helices,with bundles of unidirectional negatively charged channels formed that can facilitate lithium-ion transportation.

关键词： helical covalent polymer spiroborate single-ion conducting electrolyte

Management of distal humeral coronal shear fractures

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World Journal of Clinical Cases 2015年第5期3卷 405-417页

作者： Shahram S Yari nathan l Bowers Miguel A Craig lee M Reichel Baylor College of Medicine Medical School One Baylor Plaza Houston TX 77030 United States Baylor College of Medicine Department of Orthopedic Surgery Ben Taub General Hospital Houston TX 77030 United States

Coronal shear fractures of the distal humerus are rare,complex fractures that can be technically challenging to manage. They usually result from a low-energy fall and direct compression of the distal humerus by the radial head in a hyper-extended or semi-flexed elbow or from spontaneous reduction of a posterolateral subluxation or dislocation. Due to the small number of soft tissue attachments at this site, almost all of these fractures are displaced. The incidence of distal humeral coronal shear fractures is higher among women because of the higher rate of osteoporosis in women and the difference in carrying angle between men and women. Distal humeral coronal shear fractures may occur in isolation, may be part of a complex elbow injury, or may be associated with injuries proximal or distal to the elbow. An associated lateral collateral ligament injury is seen in up to 40% and an associated radial head fracture is seen in up to 30% of these fractures. Given the complex nature of distal humeral coronal shear fractures, there is preference for operative management. Operative fixation leads to stable anatomic reduction, restores articular congruity, and allows initiation of early range-of-motion movements in the majority of cases. Several surgical exposure and fixation techniques are available to reconstruct the articular surface fol owing distal humeral coronal shear fractures. The lateral extensile approach and fixation with countersunk headless compression screws placed in an anterior-to-posterior fashion are commonly used. We have found a two-incision approach(direct anterior and lateral) that results in less soft tissue dissection and better outcomes than the lateral extensile approach in our experience. Stiffness, pain, articular incongruity, arthritis, and ulnohumeral instability may result if reduction is non-anatomic or if fixation fails.

关键词： Coronal Shear Fractures Distal Humerus Management Approach Two-incision

Transforming growth factor-β and toll-like receptor-4 polymorphisms are not associated with fibrosis in haemochromatosis

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World Journal of Gastroenterology 2013年第48期19卷 9366-9376页

作者： Marnie J Wood lawrie W Powell Jeannette l Dixon V nathan Subramaniam Grant A Ramm Hepatic Fibrosis Group QIMR Berghofer Medical Research Institute Brisbane 4006Australia Faculty of Medicine and Biomedical Sciences The University of Queensland Brisbane 4006 Australia Department of Gastroenterology and Hepatology Royal Brisbane and Women’s HospitalBrisbane 4029 Australia Centre for the Advancement of Clinical Research Royal Brisbane and Women’s Hospital and the University of Queensland Centre for Clinical Research Brisbane 4029 Australia Iron Metabolism laboratory QIMR Berghofer Medical Research Institute Brisbane 4006 Australia Membrane Transport laboratory QIMR Berghofer Medical Research Institute Brisbane 4006 Australia

AIM:To investigate the role of genetic polymorphisms in the progression of hepatic fibrosis in hereditary ***:A cohort of 245 well-characterised C282Y homozygous patients with haemochromatosis was studied,with all subjects having liver biopsy data and DNA available for *** study assessed the association of eight single nucleotide polymorphisms(SNPs)in a total of six genes including toll-like receptor 4(TlR4),transforming growth factor-beta(TGF-β),oxoguanine DNA glycosylase,monocyte chemoattractant protein 1,chemokine C-C motif receptor 2 and interleukin-10 with liver disease *** was performed using high resolution melt analysis and *** results were analysed in relation to the stage of hepatic fibrosis in multivariate analysis incorporating other cofactors including alcohol consumption and hepatic iron ***:There were significant associations between the cofactors of male gender(P=0.0001),increasing age(P=0.006),alcohol consumption(P=0.0001),steatosis(P=0.03),hepatic iron concentration(Plymorphisms studied,none showed a significant association with hepatic fibrosis in univariate or multivariate analysis incorporating *** also specifically studied patients with hepatic iron loading above threshold levels for cirrhosis and compared the genetic polymorphisms between those with no fibrosis vs cirrhosis however there was no significant effect from any of the candidate genes ***,in this large,well characterised cohort of patients there was no association between SNPs for TGF-βor TlR4and the presence of fibrosis,cirrhosis or increasing fibrosis stage in multivariate ***:In our large,well characterised group of haemochromatosis subjects we did not demonstrate any relationship between candidate gene polymorphisms and hepatic fibrosis or cirrhosis.

关键词： Haemochromatosis Genetic polymorphism liver fibrosis Toll-like receptor 4 Interleukin 10 Monocyte chemoattractant protein 1 Chemokine(C-C motif) ligand 2 Transforming growth factor beta 8-oxoguanine DNA glycosylase

Maize Carbohydrate Partitioning Defective33 Encodes an MCTP Protein and Functions in Sucrose Export from leaves

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Molecular Plant 2019年第9期12卷 1278-1293页

作者： Thu M.Tran Tyler J.McCubbin Saadia Bihmidine Benjamin T.Julius R.Frank Baker Martin Schauflinger Clifford Weil nathan Springer Paul Chomet Ruth Wagner Jeff Woessner Karen Grote Jeanette Peevers Thomas l.Slewinski David M.Braun Division of Biological Sciences’Interdisciplinary Plant Group Missouri Maize CenterUniversity of MissouriColumbiaMO 65211USA Division of Plant Sciences University of MissouriColumbiaMO 65211USA Electron Microscopy Core Facility University of MissouriColumbiaMO 65211USA Department of Agronomy Purdue UniversityWest LafayetteIN 47907USA Department of Plant and Microbial Biology University of MinnesotaSaint PaulMN 55108USA NRGene Inc. 8910 University Center Lane\r\n S u ite 400San DiegoCA 92122USA Bayer Crop Science ChesterfieldMO 63017USA National Key laboratory for Plant Cell Technology Agricultural Genetics InstituteHanoiVietnam

To sustain plant growth,development,and crop yield,sucrose must be transported from leaves to distant parts of the plant,such as seeds and *** identify genes that regulate sucrose accumulation and transport in maize(Zea mays),we isolated carbo/iydrafe part/f/ofi/ngf defecf/Ve33(cpd33),a recessive mutant that accumulated excess starch and soluble sugars in mature *** cpd33 mutants also exhibited chlorosis in the leaf blades,greatly diminished plant growth,and reduced ***33 encodes a protein containing multiple C2 domains and transmembrane *** localization experiments showed the CPD33 protein localized to plasmodesmata(PD),the plasma membrane,and the endoplasmic *** also found that a loss-of-function mutant of the CPD33 homolog in Arabidopsis,QUIRKY,had a similar carbohydrate hyperaccumulation *** labeled sucrose transport assays showed that sucrose export was significantly lower in cpd33 mutant leaves relative to wild-type ***,PD transport in the adaxial-abaxial direction was unaffected in cpd33 mutant ***,transmission electron microscopy revealed fewer PD at the companion cell-sieve element interface in mutant phloem tissue,providing a possible explanation for the reduced sucrose export in mutant ***,our results suggest that CPD33 functions to promote symplastic transport into sieve elements.

关键词： carbohydrate accumulation companion cells phloem, plasmodesmata sieve elements symplastictransport

Q245R碳钢A-TIG焊接的数值模拟与实验研究

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Q245R碳钢A-TIG焊接的数值模拟与实验研究

作者： nathan Debucquois 哈尔滨工业大学

学位级别：硕士

活性钨极惰性气体保护焊(A-TIG)是最近一种类型的等离子焊接,其特征在于使用非自耗电极和由有源元件制成的涂层焊剂。因其与TIG焊接有相似的高质量焊接引起了最先进行业的兴趣,但与TIG焊接相比,其穿透深度有所增加。通过数值模拟和实验... 详细信息

活性钨极惰性气体保护焊(A-TIG)是最近一种类型的等离子焊接,其特征在于使用非自耗电极和由有源元件制成的涂层焊剂。因其与TIG焊接有相似的高质量焊接引起了最先进行业的兴趣,但与TIG焊接相比,其穿透深度有所增加。通过数值模拟和实验研究了用于Q245R钢的不同氧化物涂层的使用。还研究了焊接强度对焊接的影响。目的是通过数值模拟发现这两个参数对Q245R碳钢焊接的重要性。在了解了有关A-TIG模拟的现有文献后,提出并开发了用于模拟的不同模型,本论文所选用的模型是热力学平衡假设。然后在分析仿真结果后,给出了所测试的不同参数的影响。接着完成了实验过程以及对这些实验结果的分析。然后通过不同纵横比的视觉差异简单地对不同焊接效果进行了比较。根据最终目标,可以使用两种不同的方法来模拟等离子体。如果目的是确定焊接后板内的应力或相变,采用第一种方法热机械和冶金方法(TMM)。这种方法可以与特定的软件一起使用,并将侧重于凝固效果。如果更倾向于确定熔池的形成以及等离子体和熔池之间的相互作用,使用第二种方法热流体流动方法(HFF)。对于HFF方法,热物理,等离子体物理,流体物理和电磁物理必须一起解决。HFF方法用于该数值模拟,并且可以使用不同的模型进行模拟。实际上存在不同模型可用于模拟A-TIG焊接。其中一个模型包括单独模拟板,通过计算方式在正常等离子体和板之间的边界处近似不同参数,所需的不同参数,压力、热通量和电流密度可以用高斯方法近似。所用不同的输入参数,例如强度、效率、效果半径和高斯参数。另一种方法是以实验方式获取这些数据。然后,可以通过计算流体动力学软件(CFD)简单地模拟板内焊接,以便了解焊池的行为或使用特定软件来确定焊接的机械效果。本文选用第二种方法,即lTE方法(局部热力学平衡),它假定等离子体内的电子和离子的动能在局部平衡时由于足够高的碰撞水平而产生。该方法在等离子体内确认为真实,但不在边界处时需要特殊处理。该假设允许简单地使用麦克斯韦方程来解决等离子体内电子的电导率。该方法的不便之处在于该方法给出的结果高度依赖于所选择的网格划分。最后一个模型是使用非lTE假设的模型,这个模型不考虑简化,需要在扩散中使离子和电子之间产生差异。该方法解决了边界处的问题,但计算起来更复杂,并且在边界处需要更多数据。这些数据大多数都是通过实验获得的,这使得从头开始工作几乎不可能,需要使用文献中的数据或通过实验来测量这些数值。另一个模型可以用作lTE或非lTE模型的扩展。该模型的特殊性在于模拟焊接过程中形成的金属蒸汽。实际上,在焊接过程中,焊接板会释放出一些金属烟雾。这些烟雾的比例非常低,但对等离子体的热物理性质影响很大,尤其是在焊缝的周围。该模型实际上正在研究中,因为最近的研究只能模拟2种元素对等离子体的影响。尽管这些变化不容忽视,但如果没有这种模型,模拟效果会很好。为了减少计算时间模拟,在2D中使用轴对称模型完成。模拟在静态下完成,简化计算,避免了移动电极的繁重计算。这种模型不能用于精确的焊接模拟,因为不能模拟焊盘沿板的熔化和凝固,但由于焊接速度不是研究的参数,因此模拟时间不会以定性的方式对所研究的参数产生影响,只有确切的结果才能与实验相比较。在模拟中,纵横比,焊道尺寸,热影响区(HAZ)的尺寸以及熔池和等离子体内的流速将引起重视。热影响区对应于未熔化但由于受热而导致微观结构变化的区域,该温度称为Ac1。该温度已经通过计算确定,以便根据焊接参数比较该过渡区域的尺寸变化。模拟的目的是找出不同参数对焊池形状的影响。为此,计算了2组模拟,第一组模拟了焊接电流对焊池形状的影响。为此,模拟了3种不同的焊接强度,130A,150A和200A。第二组实验通过改变焊池中的氧浓度,研究涂层对焊池形状的影响。这会影响表面张力梯度。制备了3个选择的涂层,一个只有表面相变浓度的一半,一个与表面相变浓度相同,一个是表面相变浓度的一倍半。模拟结果表明,焊接强度的增加使等离子体温度升高,导致的穿透深度加深,从而使熔池的热通量增加,而且由于焊池内的焦耳效应更高,因电流导致的焊池加热。但是这种穿透深度的增加损害热影响区域的尺寸而变得更宽。此处未模拟的其他效应猜想也会影响焊池的温度,例如由于涂层对等离子体的电离引起的电弧收缩以及产生高电流的熔池顶部的熔渣的影响。电流对焊池内的流体流动有轻微影响,但效果只是最大速度范围,这是由洛伦兹力引起的,但是对流体流动的方向没有影响。模拟还表明,通过Marangoni效应,氧化物的数量正在推动焊池中的流动方向,实际上,一定量的氧化物低于表面相变量(SPT),同时导致表面张力梯度为负,因此,在焊池中向外流动,而等于或大于SPT量的氧化物含量将导致向内流动,从而导致焊接深度的急剧增加。由于选择了稳定模拟的事实,未模拟在该模拟上的影响是焊接点前后之间的阻力差。然

关键词： A-TIG 数值模拟 Q245R l.T.E假设

Outcomes following operative vs. non-operative management of blunt traumatic pancreatic injuries: a retrospective multi-institutional study

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Burns & Trauma 2016年第4期4卷 316-322页

作者： Poppy Addison Toni Iurcotta leo I.Amodu Geoffrey Crandall Meredith Akerman Daniel Galvin Annemarie Glazer nathan Christopherson Jose Prince Matthew Bank Christopher Sorrentino Joaquin Cagliani Jeffrey Nicastro Gene Coppa Ernesto P.Molmenti Horacio l.Rodriguez Rilo Department of Surgery Hofstra-Northwell School of MedicineHempsteadNYUSA Pancreas Disease Center Northwell HealthManhassetNYUSA Department of Surgery Hofstra-Northwell School of MedicineHempsteadNYUSA Department of Biostatistics Feinstein Institute for Medical ResearchManhassetNYUSA Pancreas Disease Center Northwell HealthManhassetNYUSA Department of Surgery Hofstra-Northwell School of MedicineHempsteadNYUSA Pancreas Disease Center Northwell HealthManhassetNYUSA Northwell Health 900 Northern BoulevardSuite 150Great NeckNY 11020USA

Background:Traumatic pancreatic injuries are rare,and guidelines specifying management are controversial and difficult to apply in the acute clinical *** to sparse data on these injuries,we carried out a retrospective review to determine outcomes following surgical or non-surgical management of traumatic pancreatic *** hypothesize a higher morbidity and mortality rate in patients treated surgically when compared to patients treated ***:We performed a retrospective review of data from four trauma centers in New York from 1990–2014,comparing patients who had blunt traumatic pancreatic injuries who were managed operatively to those managed *** compared continuous variables using the Mann-Whitney U test and categorical variables using the chi-square and Fisher’s exact *** analysis was performed to determine the possible confounding factors associated with mortality in both treatment ***:Twenty nine patients were managed operatively and 32 *** was a significant difference between the operative and non-operative groups in median age(37.0 vs.16.2 years,P=0.016),grade of pancreatic injury(grade I;30.8 vs.85.2%,P value for all comparisonslood transfusion(55.2 vs.15.6%,P=0.0012),other abdominal injuries(79.3 vs.38.7%,P=0.0014),pelvic fractures(17.2 vs.0.00%,P=0.020),intensive care unit(ICU)admission(86.2 vs.50.0%,P=0.003),median length of stay(lOS)(16.0 vs.4.0 days,Plity(27.6 vs.3.1%,P=0.010).Conclusions:Patients with traumatic pancreatic injuries treated operatively were more severely injured and suffered greater complications than those treated *** greater morbidity and mortality associated with these patients warrants further study to determine optimal triage strategies and which subset of patients is likely to benefit from surgery.

关键词： Injury Management Non-operative Operative Pancreas Trauma