一种三元共聚物磷酸盐的合成及性能研究

由丙烯酰胺、丙烯酸、3-二甲胺基烯丙基磷酸在过硫酸铵-亚硫酸氢钠氧化还原引发体系下合成了一种新型的AM/AA/DMAAPA三元共聚物.确立了最佳反应条件:AM/AA= 3/1(wt％),引发剂用量0.5wt％,pH为7,反应温度为40℃;并通过红外光谱分析确认了AM/AA/DMAAPA三元共聚物结构.当Na+;Cab,...     

Centrality and energy dependence of rapidity correlation patterns in relativistic heavy ion collisions

The centrality and energy dependence of rapidity correlation patterns are studied in Au+Au collisions by using AMPT with string melting,RQMD and UrQMD models.The behaviors of the shortrange correlation(SRC)and the long-range correlation(LRC)are presented clearly by two spatial-position dependent correlation patterns.For centrality dependence.UrQMD and RQMD give similar results as those in AMPT,i.,e., in most central collisions,the correlation structure is flatter and the correlation range is larger,which indicates a long range rapidity correlation.A long range rapidity correlation showing up in RQMD and UrQMD implies that patton interaction is not the only source of long range rapidity correlations.For energy dependence,AMPT with string melting and RQMD show quite different results.The correlation patterns in RQMD at low collision energies and those in AMPT at high collision energies have similar structures,i.e.aconvex curve.while the correlation patterns in RQMD at high collision energies and those in AMPT at low collision energies show fiat structures,having no position dependence.Long range rapidity correlation presents itself at high energy and disappears at low energy in RQMD,which also indicates that long range rapidity correlations may come from some trivial effects,rather than the parton interactions.     

Ablation mechanism of PTFE under 157 nm irradiation

We report time- and mass-resolved measurements on neutral particles emitted from polytetrafluoroethylene (PTFE) during exposure to 157-nm laser radiation at fluences where etching is observed. By comparing the time-of-flight signals over a range of masses, we conclude that (CF₂) _N fragments for N=1–6 are emitted directly from the surface in substantial quantities. In contrast, the monomer (N=2) is the principal product during irradiation at 248 nm, where thermal decomposition is important. The time-of-flight signals of all the (CF₂) _N fragments show fast components with kinetic energies on the order of an electron volt. These high kinetic energies are consistent with photochemical scission of the polymer backbone, where a fraction of the excitation energy is delivered to the fragment as kinetic energy. Although clean etching is observed under these conditions, the great majority of the mass removed from the target appears as much larger fragments that do not reach our detector. The nature of this material and its affect on the velocity distribution of the observed (CF₂) _N fragments is discussed.     

The effects of vacuum annealing on the structure and surface chemistry of iron nanoparticles

In order to increase the longevity of contaminant retention, a method is sought to improve the corrosion resistance of iron nanoparticles (INP) used for remediation of contaminated water and thereby extend their industrial lifetime. A multi-disciplinary approach was used to investigate changes induced by vacuum annealing (<5 × 10^?8 mbar) at 500 °C on the bulk and surface chemistry of INP. The particle size did not change significantly as a result of annealing but the surface oxide thickness decreased from an average of 3–4 nm to 2 nm. BET analysis recorded a decrease in INP surface area from 19.0 to 4.8 m² g^?1, consistent with scanning electron microscopy (SEM) and transmission electron microscopy (TEM) observations which indicated the diffusion bonding of previously discrete particles at points of contact. X-ray diffraction (XRD) confirmed that recrystallisation of the metallic cores had occurred, converting a significant fraction of poorly crystalline iron to bcc α-Fe and Fe₂B phases. X-ray photoelectron spectroscopy (XPS) indicated a change in the surface oxide stoichiometry from magnetite (Fe₃O₄) towards wüstite (FeO) and the migration of boron and carbon to the particle surfaces. The improved core crystallinity and the presence of passivating impurity phases at the INP surfaces may act to improve the corrosion resistance and reactive lifespan of the vacuum annealed INP for environmental applications.     

CLASSIFICATION OF SOLUTIONS TO HIGHER FRACTIONAL ORDER SYSTEMS

Let 0 ＜ α,β ＜ n and f,g ∈ C([0,∞) ×[0,∞)) be two nonnegative functions.We study nonnegative classical solutions of the system{(-Δ)α/2u=f(u,v) in Rn,(-Δ)β/2 v =g...     

ChemInform Abstract: Polymorphism of CsAlF4. Synthesis and Structure of Two New Crystalline Forms.

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.     

三元混配铜(Ⅱ)配合物的晶体结构、DNA作用及其生物活性

利用溶剂缓慢挥发法合成了以5-氯-2-(2'-吡啶基)苯并咪唑为主配体、L-苯丙氨酸根为辅助配体的三元混配铜(I)配合物:[Cu(HPBC)(L-Phe)(H2O)]C1O4(简称为1,HPBC=5-氯-2-(2'-吡啶基)苯并咪唑,L-Phe=L-苯丙氨酸根).采用元素分析、红外光谱、紫外可见光谱、摩尔电导率测定和电...