Aha1 Exhibits Distinctive Dynamics Behavior and Chaperone-Like Activity

Aha1 is the only co-chaperone known to strongly stimulate the ATPase activity of Hsp90. Meanwhile, besides the well-studied co-chaperone function, human Aha1 has also been demonstrated to exhibit chaperoning activity against stress-denatured proteins. To provide structural insights for a better understanding of Aha1’s co-chaperone and chaperone-like activities, nuclear magnetic resonance (NMR) techniques were used to reveal the unique structure and internal dynamics features of full-length human Aha1. We then found that, in solution, both the two domains of Aha1 presented distinctive thermal stabilities and dynamics behaviors defined by their primary sequences and three-dimensional structures. The low thermal stability (melting temperature of Aha1^28–162: 54.45 °C) and the internal dynamics featured with slow motions on the µs-ms time scale were detected for Aha1’s N-terminal domain (Aha1N). The aforementioned experimental results suggest that Aha1N is in an energy-unfavorable state, which would therefore thermostatically favor the interaction of Aha1N with its partner proteins such as Hsp90’s middle domain. Differently from Aha1N, Aha1C (Aha1’s C-terminal domain) exhibited enhanced thermal stability (melting temperature of Aha1^204–335: 72.41 °C) and the internal dynamics featured with intermediate motions on the ps-ns time scale. Aha1C’s thermal and structural stabilities make it competent for the stabilization of the exposed hydrophobic groove of dimerized Hsp90’s N-terminal domain. Of note, according to the NMR data and the thermal shift results, although the very N-terminal region (M1-W27) and the C-terminal relaxin-like factor (RLF) motif showed no tight contacts with the remaining parts of human Aha1, they were identified to play important roles in the recognition of intrinsically disordered pathological α-synuclein.     

脱水催化剂的改性对浆态床一步法合成二甲醚的影响

 以Cu(NO3)2为前驱体,以水、丙酮或乙二醇为溶剂,以γ-Al2O3为载体,采用等体积浸渍法制备了用于合成气一步法制二甲醚的脱水-变换双功能催化剂,并对其还原性能、晶态分布、还原态的酸性及催化性能进行了研究. H2-TPR结果表明,以乙二醇为溶剂制备的催化剂上可还原氧化铜的量最多. XRD结果表明,以水为溶剂制备的催化剂上,氧化铜并未完全均匀地分散在氧化铝表面,而是有一部分以单质铜或铜铝化合物的形式存在; 而以丙酮或乙二醇为溶剂制备催化剂时,氧化铜分布均匀. 还原态催化剂NH3-TPD结果表明,以乙二醇为溶剂制备的催化剂上,酸性中心主要集中在弱酸位上. 浆态床搅拌釜中合成反应的结果表明,用氧化铜对脱水催化剂进行改性,能改善催化剂的催化性能,提高CO转化率和产物中二甲醚的选择性,抑制副反应的发生. 非水溶剂的使用对CO转化率没有明显的影响,但可改变催化剂上酸中心的分布,提高二甲醚的选择性,并抑制副反应的发生.     

Preparation of cuprous oxides with different sizes and their behaviors of adsorption,visible-light driven photocatalysis and photocorrosion

Cuprous oxide (Cu₂O) nanoparticles and microparticles have been prepared by liquid phase chemical synthesis. The samples were characterized by means of SEM, XRD, UV/DRS and XPS. It was presented that as-prepared Cu₂O nanoparticles are substantially stable in ambient atmosphere and the Cu⁺ as main state exists on the surface of Cu₂O nanoparticles. As-prepared Cu₂O microparticles can exist stably as a Cu₂O/CuO core/shell structure; and the Cu²⁺ as main state exists on the surface of Cu₂O microparticles. The behaviors of adsorption, photocatalysis and photocorrosion of Cu₂O particles with different sizes were investigated in detail. The results show that Cu₂O nanoparticles are very easy to photocorrosion during the photocatalytic reaction, which cannot be used as photocatalyst directly to degrade organic compound, although as-prepared Cu₂O nanoparticles exhibit special property of adsorption. Cu₂O microparticles have a higher photocatalytic activity than Cu₂O nanoparticles because of its slower photocorrosion rate, although Cu₂O microparticles have much lower adsorption capacity than Cu₂O nanoparticles. The mechanisms of photocatalysis and photocorrosion for Cu₂O under visible light were also discussed.     

Synergistic flame-retardant effects of ammonium polyphosphate and AC-Fe2O3 in epoxy resin

Journal of Thermal Analysis and Calorimetry - The synergistic flame-retardant and smoke suppression properties of ammonium polyphosphate (APP) and activated carbon-supported Fe2O3 (AC-Fe2O3) on...     

Low temperature CO oxidation over unsupported nanoporous gold

Supported Au nanoclusters are well-known for their unusual properties in catalysis. We describe here that nanostructured porous Au made via dealloying represents a new class of unsupported catalysts with extraordinary activities in important reactions such as CO oxidation. Although nanoporous Au may contain some oxides on the surface, our results demonstrate that it is metallic Au that plays the main role in this catalytic reaction. Furthermore, this material has good low-temperature catalytic stability and is extremely CO tolerant.     

Mechanism study on adsorption of acidified multiwalled carbon nanotubes to Pb(II)

Adsorption of acidified multiwalled carbon nanotubes (MWCNTs) to heavy metal using Pb(II) as a model was investigated and characterized by many techniques. The main adsorption mechanism of acidified MWCNTs to Pb(II) is proposed on the basis of adequate analysis. The results show that the oxygenous functional groups can be formed on MWCNTs after MWCNTs were treated by concentrated nitric acid. The oxygenous functional groups play an important role in Pb(II) adsorption to form chemical complex adsorption, which accounts for 75.3% of all the Pb(II) adsorption capacity. The Pb(II) in the form of PbO, Pb(OH)(2), and PbCO(3) adsorbed on the surface of the acidified MWCNTs is only 3.4% of the total Pb(II) adsorption capacity. The Pb(II) species adsorbed on acidified MWCNTs mainly aggregate on the ends and at the defects sites on the acidified MWCNTs.     

An accurate analytical formula for the van der Waals potentials of homonuclear rare-gas dimers with one adjustable parameter

In the present article, the Tang–Toennies–Yiu (TTY) potential model is modified by introducing one adjustable parameter. Then, the van der Waals potentials of He₂, Ne₂, Ar₂, Kr₂, and Xe₂ are calculated by this model with the adjustable parameter being determined by the well determined well depth D_e of these systems. Based on the derived potentials, the vibrational energy spacings of these systems are also calculated. It is shown that the present derived potentials and vibrational energy spacings agree well with experiment and other theoretical calculations. Finally, the normalization constant A in the asymptotic wave function of rare-gas atoms is estimated. The present derived normalization constant A is very close to the one by calculating the ratio between the Hartree–Fock function and the asymptotic wave function. The results confirm that absorbing the first-order polarization energy into the exchange energy expression is a well approximation for the present systems.     

气相色谱法测定新型多元复合液肥中二羧酸

建立了新型多元复合液肥中丁二酸、戊二酸、己二酸的气相色谱分析方法。色谱条件：５％ＳＥ－３０不锈钢填充柱,程序升温,内标物为丙二酸二乙酯,３种二元酸二乙酯分别在２．３～９．３μｇ,１０．８～４３．２μｇ和２．８～１１．０μｇ质量范围内,其样品质量与样品峰面积和内标峰面积之比呈良好的线性关系,相关系数ｒ≥０．９９５５。     

A cancer cell turn-on protein-CuSMn nanoparticle as the sensor of breast cancer cell and CH3O-PEG-phosphatide

A cancer activated protein-inorganic nanoparticle was used as breast cancer cell turn-on fluorescence sensor and NIR activated attenuator.     

A simple preparation of nitrogen doped titanium dioxide nanocrystals with exposed (001) facets with high visible light activity

Nanoscaled nitrogen doped anatase TiO(2) with dominant (001) facets, which exhibited high photocatalytic activity and excellent photoelectrochemical properties under visible light irradiation, was successfully synthesized by solvothermal treatment of TiN in acidic NaBF(4) solution for the first time.