An update on the electrolytic conductivity values for the primary standard KCl solutions: Conversion to the ITS-90 temperature scale

A new international temperature scale has replaced the 1968 scale. Here, we report the changes required in our previous results for primary conductivity standards for 0.01, 0.1 and 1.0 Demal KCl solutions at 0,18 and 25°C.     

三元配合物[Cu(L-tyr)(TATP)(H_2O)]ClO_4·H_2O的合成、晶体结构及芳环堆积作用

合成了新的三元配合物 [Cu(L tyr) (TATP) (H2 O) ]ClO4 ·H2 O (L tyr=L 酪氨酸 ,TATP =1,4,8,9 四氮三联苯 ) ,并用红外光谱和电子顺磁共振谱进行了表征 .用X射线单晶衍射测定了配合物结构 ,晶体属单斜晶系 ,空间群P2 1,晶胞参数 :a =0 .786 2 (2 )nm ,b=1.0 5 10 (5 )nm ,c=1.476 8(3)nm ,β =97.74(3)° ,Z =2 ,V =1.2 0 92 (5 )nm3 ,R1=0 .0 34 1,wR2 =0 .0 919.中心Cu(Ⅱ )离子具有变形四方锥配位结构 ,与TATP中两个氮原子、L tyr的氨基氮和羧基氧原子及一个水分子配位 .晶体中芳环堆积及氢键作用类似于稳定DNA双螺旋结构的碱基之间的作用 ,具有分子识别的特点 .     

Total synthesis of cytotoxic anhydrophytosphingosine pachastrissamine (jaspine B)

Starting from L-serine, a stereoselective synthesis of pachastrissamine, a structurally novel anhydrosphingosine derivative, is reported in this Letter. [structure: see text]     

Grafting miniature DNA binding proteins

Miniature proteins serve as leads for biological and medicinal applications by positioning all amino acids necessary for biomolecular recognition on a compact protein structure. Protein grafting was recently used to create miniature helical proteins with high DNA binding affinity and specificity.     

A comparison of the intramolecular and intermolecular hydrogen bonding of N,N′-ethylenebis(aminobenzylidene) in the solid state with its salen analogue

The crystal structure of H₂amben has been elucidated for the first time. The close NH?N contact between neighbouring molecules supports strongly the notion that intermolecular hydrogen bonding exists within the crystal lattice, creating a series of molecular chains, which are crosslinked in a three-dimensional array. This intermolecular bonding is suggested to account for the anomalously high melting point of H₂amben (176-178 °C) compared to its H₂salen counterpart (126-128 °C). Although strong intramolecular forces are present in both ligands, H₂salen contains no intermolecular hydrogen bonds.     

pH位移法评定阻垢剂的阻垢性能

介绍了一种评定阻垢剂性能的新方法，即在某一pH范围内，通过测定加入阻垢剂后Ca(HCO3）2过饱和溶液的起始PH与一定时间后的稳定PH之差，根据差值的变化评定阻垢的阻垢性能，通过与国内普遍采用的评定阻垢剂性能的方法－静态阻垢法和鼓泡法的比较，证明此法简便、快捷，重现性好，可信度高。     

Resonance-enhanced,multiphoton-ionization spectroscopy of NH3

The multiphoton-ionization spectroscopy of NH₃ has been explored using three-photon ionization through a two-photon resonant intermediate state. This method provides greatly increased sensitivity when compared to three-photon excitation to the intermediate state.