Reorientation of anisotropy in a square well quantum hall sample

We have measured magnetotransport at half-filled high Landau levels in a quantum well with two occupied electric subbands. We find resistivities that are isotropic in perpendicular magnetic field but become strongly anisotropic at nu = 9/2 and 11/2 on tilting the field. The anisotropy appears at an in-plane field, B(ip) approximately 2.5 T, with the easy-current direction parallel to B(ip) but rotates by 90 degrees at B(ip) approximately 10 T and points now in the same direction as in single-subband samples. This complex behavior is in quantitative agreement with theoretical calculations based on a unidirectional charge density wave state model.     

Super-hydrophobic, highly adhesive, polydimethylsiloxane (PDMS) surfaces

Super-hydrophobic surfaces have been fabricated by casting polydimethylsiloxane (PDMS) on a textured substrate of known surface topography, and were characterized using contact angle, atomic force microscopy, surface free energy calculations, and adhesion measurements. The resulting PDMS has a micro-textured surface with a static contact angle of 153.5° and a hysteresis of 27° when using de-ionized water. Unlike many super-hydrophobic materials, the textured PDMS is highly adhesive, allowing water drops as large as 25.0 μL to be inverted. This high adhesion, super-hydrophobic behavior is an illustration of the "petal effect". This rapid, reproducible technique has promising applications in transport and analysis of microvolume samples.     

Surface-initiated synthesis of poly(3-methylthiophene) from indium tin oxide and its electrochemical properties

Poly(3-methylthiophene) (P3MT) was synthesized directly from indium tin oxide (ITO) electrodes modified with a phosphonic acid initiator, using Kumada catalyst transfer polymerization (KCTP). This work represents the first time that polymer thickness has been controlled in a surface initiated KCTP reaction, highlighting the utility of KCTP in achieving controlled polymerizations. Polymer film thicknesses were regulated by the variation of the solution monomer concentration and ranged from 30 to 265 nm. Electrochemical oxidative doping of these films was used to manipulate their near surface composition and effective work function. Doped states of the P3MT film are maintained even after the sample is removed from solution and potential control confirming the robustness of the films. Such materials with controllable thicknesses and electronic properties have the potential to be useful as interlayer materials for organic electronic applications.     

Solid-Phase Synthesis of a Monofunctional trans-a(2)Pt(II) Complex Tethered to a Single-Stranded Oligonucleotide

Cross-linking ability is possible with the oligonucleotide-tethered, monofunctional trans-Pt(II) complex shown. It was synthesized by a novel solid-phase approach comprising conjugation of immobilized tetrathymidylic acid with a trans-a(2)Pt(II) building unit, ammonolysis, and transformation of the resulting complex (R=1-N-cyclohexylmethylthyminate) into the chloro derivative (R=Cl). a=NH(2)CH(3), T=thymine.     

Direct imaging of aligned neurofilament networks assembled using in situ dialysis in microchannels

We report a technique to produce aligned neurofilament networks for direct imaging and diffraction studies using in situ dialysis in a microfluidic device. The alignment is achieved by assembling neurofilaments from protein subunits confined within microchannels. Resulting network structure was probed by polarized optical microscopy and atomic force microscopy, which confirmed a high degree of protein alignment inside the microchannels. This technique can be expanded to facilitate structural studies of a wide range of filamentous proteins and their hierarchical assemblies under varying assembly conditions.     

内蒙古地区天然植物沙棘果中黄色素的提取工艺及性质研究

以内蒙古地区沙棘果实为原料，研究了提取黄色素的工艺条件，同时对该色素的性质进行了初步探讨。结果表明，以95％的乙醇溶液作浸提剂，提取的黄色素浓度最高，工艺流程简单易行，且无毒，无污染。对提取的黄色素进行的性质试验表明，沙棘黄色素对光、热具有较好的稳定性，适用于酸性或弱碱性的食品中，葡萄糖、氧化剂(H2O2)、还原剂(Na2SO3)等食品添加剂均无明显影响以上结果为这种优良天然色素的开发与应用提供了参考。     

Noninvasive imaging of cell death using an Hsp90 ligand

Cell death plays a central role in normal physiology and in disease. Common to apoptotic and necrotic cell death is the eventual loss of plasma membrane integrity. We have produced a small organoarsenical compound, 4-(N-(S-glutathionylacetyl)amino)phenylarsonous acid, that rapidly accumulates in the cytosol of dying cells coincident with loss of plasma membrane integrity. The compound is retained in the cytosol predominantly by covalent reaction with the 90 kDa heat shock protein (Hsp90), the most abundant molecular chaperone of the eukaryotic cytoplasm. The organoarsenical was tagged with either optical or radioisotope reporting groups to image cell death in cultured cells and in murine tumors ex vivo and in situ. Tumor cell death in mice was noninvasively imaged by SPECT/CT using an (111)In-tagged compound. This versatile compound should enable the imaging of cell death in most experimental settings.     

Stable heteroleptic complexes of divalent lanthanides with bulky pyrazolylborate ligands--iodides, hydrocarbyls and triethylborohydrides

The reaction of YbI(2) with KTp(Me2) gives (Tp(Me2))YbI(THF)(2) (1-Yb) as a thermally unstable product. Use of the more hindered KTp(tBu,Me) gave (Tp(tBu,Me))LnI(THF)(n) (Ln = Sm, n = 2, 2-Sm; Ln = Yb, n = 1, 2-Yb). The crystal structures of both these compounds are reported. Adducts with neutral ligands such as pyridines and isonitriles can be prepared and the crystal structures of [(Tp(tBu,Me))YbIL(n)] (L = CN(t)Bu, n = 1; L = 3,5-lutidine, n = 2) are described. 2-Sm can be oxidized using AgBPh(4) to give [(Tp(tBu,Me))SmI(THF)(2)]BPh(4). Compounds 2-Sm and 2-Yb are useful starting materials for the preparation of heteroleptic compounds by metathesis with appropriate potassium reagents. The preparations and characterization of the hydrocarbyls (Tp(tBu,Me))Ln{CH(SiMe(3))(2)} (Ln = Sm, 5-Sm; Yb, 5-Yb) and [(Tp(tBu,Me))Ln{CH(2)(SiMe(3))}(THF)] (Ln = Yb, 6a-Yb) and the triethylborohydrides [(Tp(tBu,Me))Ln(HBEt(3))(THF)(n)] (Ln = Sm, n = 0, 7-Sm; Yb, n = 1, 7-Yb) are reported, as well as the crystal structures of 5-Sm and 5-Yb, and the THF adducts 6a-Yb and [(Tp(tBu,Me))Sm{CH(SiMe(3))(2)}(THF)], 5a-Sm.     

An MRI‐Sensitive,Non‐Photobleachable Porphysome Photothermal Agent

Photothermal therapy makes use of photothermal sensitizers and laser light to thermally ablate diseased tissues. Porphysome nanoparticles offer a nontoxic alternative to inorganic nanocrystals for the efficient conversion of light into heat. Mn³⁺ ions were incorporated directly into the building blocks of our porphysome nanoparticles, thus imparting MRI sensitivity while simultaneously improving photostability and maintaining high photothermal efficiency. Mn porphysomes are as photothermally effective as free‐base porphysomes and can rival gadolinium diethylenetriaminepentaacetate (Gd‐DTPA) for MRI contrast generation. Their MRI contrast generation, photothermal efficiency, and photostability are unprecedented for an all‐organic nanoparticle composed of a single functional component.     

种植沙生植物--沙棘改善内蒙古地区生态环境

结合内蒙古地区现状，对沙棘的生物学和生态学特性、沙棘属植物化学成分和微量元素及种植沙生植物——沙棘的重要性和必要性进行了详细的研究和探讨。研究表明，沙棘属植物具有极强的生态适应性并富含多种营养成分和生物活性物质，并以耐干旱、耐瘠薄、萌蘖及固氮能力强等特点被称为治理非宜林地水土流失、改善生态环境的先锋树种。种植沙棘是治理内蒙古脆弱生态环境最经济、最有效的措施，是贫瘠的不毛之地发展经济、增加收入的经济树种。另外．种植沙棘的技术简便，容易掌握，投资少，见效快。