用四种离散变换主组分回归方法分辨重叠吸收光谱

将离散小波变换、小波包变换、傅里叶变换和离散余弦变换与主组分回归方法结合构成4种离散变换主组分回归方法,编制了离散变换主组分回归方法的计算程序。将离散变换主组分回归方法用于处理对硝基甲苯、对硝基酚和对硝基苯胺混合物的重叠紫外吸收光谱数据。结果表明,离散变换主组分回归方法优于主组分回归方法,试样质量浓度的预测值与实际值的相对预测标准误差由3.81%降至约1.11%。     

双向拉伸聚对苯二甲酸乙二醇酯驻极体的分立陷阱

用热释电极化温度扫描法在温度间隔为５℃的条件下研究了经过双向拉伸具有不同平面取向度的聚对苯二甲酸乙二醇酯ＰＥＴ驻极体试样，分离出对解俘获电流峰贡献的各分立陷阶电流峰．随平面取向度和脂肪链反式构象含量的提高，各分立陷阶深度增加．结构缺陷种类的增多使分立陷阱数由二个增至六个，并导致分立陷阱深度分布加宽．     

A stepwise approach to the formation of heterometallic discrete complexes and infinite architectures

A strategy for the controlled construction of heterobimetallic discrete complexes and 1-D coordination networks is presented. The organic ligand based on the methanedithiolate group and the 4,5-diazafluorene moiety behaving as primary and secondary coordination poles respectively leads to the formation of a series of discrete metal complexes with various geometries via binding through the dithiolate site. The observed coordination geometries range from square-planar for Ni(ii) and Pd(ii) to distorted tetrahedral for Zn(ii) and Hg(ii). The square-planar Pd(ii) complex affords a discrete bimetallic trinuclear complex when treated with a capped Ni(ii) center. All three Ni(ii), Pd(ii) and Hg(ii) discrete complexes have been also shown to behave as metallatectons leading to the generation of infinite networks in the presence of bridging cations such as sodium.     

Equation of state for monomolecular films of melittin at air-water interface

The spread monolayers of proteins at the air-water interface have been reported to be very useful model membrane systems. The charged protein monolayers have been analyzed by using the Gouy-Chapman (-Stern) models. These models gave satisfactory analyses of “non-membrane” proteins, but could not be used for the data of charged melittin monolayers (“membrane protein”). In order to describe these data, a new discrete (net) charge model is developed, and the equation of state for these two-dimensional films is discussed herein. This study shows, for the first time, that discrete (net) charges are present in charged melittin (a peptide with 26 amino acids) monolyers. The measured surface pressure,Π, and surface potential,Δψ, are analyzed with the help of the discrete charge model.     

Ambidentate ligands capable of variable bond angles in the coordination-driven self-assembly of discrete Pt macrocycles

Flexible, ambidentate pyridyl-carboxylate based donor ligands such as sodium 3-(3-pyridyl)benzoate, sodium 4-(3-pyridyl)benzoate, and potassium 4-(3-pyridyl)ethynylbenzoate self-assemble into discrete [2 + 2] macrocyclic species instead of infinite networks when combined with a 90 degrees platinum-containing acceptor. In each case, only one isomeric ensemble is selectively formed in high yield. All products are characterized by electrospray ionization mass spectrometry (ESI-MS) and 31P{1H} and 1H NMR spectroscopy. They are the first examples of discrete supramolecules incorporating flexible, ambidentate donor ligands. Despite their potential versatility, these pyridyl-carboxylate donors adjust their bonding directionality to accommodate a rigid platinum acceptor in the formation of one discrete ensemble.     

Discrete Stimuli‐Responsive Multirotaxanes with Supramolecular Cores Constructed through a Modular Approach

The synthesis of discrete multirotaxanes with well‐defined structures remains a great challenge. Herein, we present the successful construction of diverse discrete multirotaxanes with well‐defined supramolecular metallacycles as cores by a modular approach. Moreover, these novel multirotaxanes featured a stimuli‐responsive property that enabled the introduction and removal of the bromide anion by taking advantage of dynamic nature of the supramolecular metallacycle scaffold. Through the combination of rotaxane‐containing prefunctionalized building blocks with the corresponding different organoplatinum(II) acceptor building blocks (60, 120, or 180°), diverse discrete multirotaxanes with well‐defined metallacycles (rhomboid or hexagon) as cores as well as certain numbers of rotaxane units were successfully obtained quantitatively by means of coordination‐driven self‐assembly. Furthermore, owing to the existence of a dynamic metallacycle as the supramolecular cores, the resultant multirotaxanes showed anion‐induced disassembly and reassembly properties, which allowed for the reversible transformation between multirotaxanes and the corresponding individual rotaxane‐containing building blocks. Therefore, this research not only enriches the family of discrete multirotaxanes, but also provides a novel strategy for the construction of “smart” stimuli‐responsive multirotaxane systems.     

Environmental effects on the spectroscopic properties of gallic acid: a combined classical and quantum mechanical study

The solvation of gallic acid (in water and acetonitrile) is studied by means of its spectroscopic properties. IR, UV, and NMR spectra are predicted by using various solvation models obtained in terms of both purely classical and density functional approaches. Comparison with experiments is used to validate solvation models. Hydrogen-bond and long-range (or bulk) effects are evaluated by comparing different solvation models. A continuum-only approach, a purely discrete, and a mixed continuum/discrete approach based on quantum-mechanical and classical molecular-dynamics solute-solvent clusters are tested.     

A complete macroion-"blackberry" assembly-macroion transition with continuously adjustable assembly sizes in {Mo132} water/acetone systems

A complete, continuous transition from discrete macroions to blackberry structures, and then back to discrete macroions, is reported for the first time in the system of {Mo132}/water/acetone, with {Mo132} (full formula (NH4)42[Mo132O372(CH3COO)30(H2O)72].ca.300H2O.ca.10CH3COONH4) as the C60-like anionic polyoxomolybdate molecular clusters. Laser light scattering studies reveal the presence of the self-assembled {Mo132} blackberry structures in water/acetone mixed solvents containing 3 vol % to 70 vol % acetone, with the average hydrodynamic radius (Rh) of blackberries ranging from 45 to 100 nm with increasing acetone content. Only discrete {Mo132} clusters are found in solutions containing <3 vol % and >70 vol % acetone. The complete discrete macroion (cluster)-blackberry-discrete macroion transition helps to identify the driving forces behind the blackberry formation, a new type of self-assembly process. The charge density on the macroions is found to greatly affect the blackberry formation and dissociation, as the counterion association is very dominant around blackberries. The transitions between single {Mo132} clusters and blackberries, and between the blackberries with different sizes, are achieved by only changing the solvent quality.     

Synthesis and crystal structure of two new discrete, neutral complexes of manganese and zinc using a rigid organic clip

Two discrete neutral dimanganese(II) and tetrazinc(II) complexes were synthesized from a rigid organic clip and the corresponding metal acetates. The compounds were characterized by elemental analysis and single crystal X-ray diffraction study. The manganese species is a dinuclear discrete product with two disordered acetates bridging two manganese centers, while the zinc one consists of two octahedral and two tetrahedral Zn(II) centers with both bridging acetates and triply micro(3)-hydroxides. Variable temperature magnetic measurement reveals the existence of weak antiferromagnetic interaction (J = -1.6 cm(-)(1); H = -2JS(1).S(2)) within the manganese complex.     

The influence of discrete surface charges on the force between charged surfaces

The force between two parallel charged flat surfaces, with discrete surface charges, has been calculated with Monte Carlo simulations for different values of the electrostatic coupling. For low electrostatic coupling (small counterion valence, small surface charge, high dielectric constant, and high temperature) the total force is dominated by the entropic contribution and can be described by mean field theory, independent of the character of the surface charges. For moderate electrostatic coupling, counterion correlation effects lead to a smaller repulsion than predicted by mean field theory. This correlation effect is strengthened by discrete surface charges and the repulsive force is further reduced. For large electrostatic coupling the total force for smeared out surface charges is known to be attractive due to counterion correlations. If discrete surface charges are considered the attractive force is weakened and can even be turned into a repulsive force. This is due to the counterions being strongly correlated to the discrete surface charges forming effective, oppositely directed, dipoles on the two walls.     

Two Discrete Cu-Complexes Constructed from a Multidentate N-Containing Dinucleating Ligand

Two comparable discrete complexes [CuⅡ(CH3CN)2L2]·2(ClO4) 1 and [CuI2I2L2]·(DMF)2 2 were successfully synthesized by the reaction of CuⅡ and CuⅠ salts with a novel dinucleating ligand 2,5-bis(3-pyridinylmethylthio)-1,3,4-thiadiazole)(L),respectively.Complex 1 presents a single nuclear structure while 2 has a dimeric structure where two CuI ions are doubly bridged by halide ions in a μ2-fashion.Both discrete molecules were outspreaded into a one-dimensional supramolecular chain via aromatic interactions such as C-H…π and π…π interactions.     

Intensity analysis of overlapped discrete and continuous absorption by spectral simulation: the electronic transition moment for the B-X system in I2

The spectrum of I(2) is examined anew in the wavelength region 520-640 nm, where discrete absorption in the B-X transition is prominent. The spectrum is recorded with high quantitative precision at moderate resolution (0.1 nm) and is analyzed by least-squares spectral simulation, yielding the B-X electronic transition strength ∣μ(e)∣(2) with unprecedented precision (<2% relative standard error) over most of the studied region. The analysis also yields directly new estimates of the continuous absorption in this region, which support previous assessments of the A ← X transition but lower the C((1)Π(u)) ← X transition strength by 25%. The new analysis method is applicable to any situation where the discrete spectrum can be simulated reliably.     

Ag(I) complexes with alkylidene-bis(2-aminopyrimidines) as building units for discrete metallomacrocyclic frames. A structural and solution study

Alkylidene-bis(2-aminopyrimidines) (pyr2Cx, x = 2-5) are useful ligands to interact with Ag(I) yielding discrete metallocycles. Crystal structures of the [(pyr2C2)Ag(NO3)]2 and [(H-pyr2C4)Ag(NO3)2]2 have been isolated where each macrocyclic moiety interacts with their surroundings through weak interactions, yielding 3D discrete structures, On the other hand, the solution study shows that the equilibrium constants for the formation of Ag(pyr2Cx)+ complexes are higher than the literature values for Ag(I) complexes with single pyrimidines, although the differences could be explained by invoking the solid-state structures of the Ag(I)-pyr2Cx complexes.     

Superbase route to supertetrahedral chalcogenide clusters

Supertetrahedral Tn clusters are exact fragments of a cubic ZnS type lattice. Thus far, Tn clusters up to T4 with 20 metal sites can be synthesized in a discrete molecular form. Yet, synthesis of larger discrete supertetrahedral clusters still remains a great challenge, likely due to the rapidly increasing negative charge on the cluster as the size goes up. By using organic superbases (DBN and DBU) to help stabilize the negative charge, a family of discrete supertetrahedral chalcogenide clusters with sizes spanning from T3 (10 metal sites) to T5 (35 metal sites) have been made. The T5 cluster represents the largest molecular supertetrahedral Tn cluster known to date.     

Incremental solvation of nonionized and zwitterionic glycine

Microsolvation and combined microsolvation-continuum approaches are employed in order to examine the structures and relative energies of nonionized (N) and zwitterionic (Z) glycine clusters. Bridging structures are predicted to be the global minima after 3-5 discrete water molecules are included in the calculations. Calculations incorporating electron correlation stabilize the zwitterionic structures by about 7-9 kcal/mol relative to the N structures regardless of the number of discrete water molecules considered. Continuum calculations stabilize the Z structures relative to N structures; this effect decreases as the number of discrete water molecules is increased. Eight water molecules do not appear to fully solvate glycine.     

Mechanical properties of thermoplastic polyester elastomer controlled by blending with poly(butylene terephthalate)

Thermoplastic polyester elastomer (TPEE) blends with poly(butylene terephthalate) (PBT) were prepared by melt compounding for the phase morphology and mechanical property studies. Although PBT is immiscible with the continuous soft poly(tetramethylene glycol) (PTMEG) phase of TPEE, it is miscible with the discrete hard PBT one of TPEE. Therefore, PBT and TPEE are compatible and their blends reveal very low level of interfacial tension and very small size of discrete domains, as well as good interfacial adhesion between two phases, which provide high possibility to prepare TPEE alloys with controllable properties. Mechanical test results reveal that both the modulus and yield and tensile strengths increase with increasing weight ratios of PBT. The increased system rigidity and decreased system plasticity are further confirmed by the cyclic tensile tests. The main objective of this work is to provide useful information on the structure and property control of TPEE by simple mixing with aromatic polyesters.     

Discrete π‐Stacks from Self‐Assembled Perylenediimide Analogues

The formation of well‐defined finite‐sized aggregates represents an attractive goal in supramolecular chemistry. In particular, construction of discrete π‐stacked dye assemblies remains a challenge. Reported here is the design and synthesis of a novel type of discrete π‐stacked aggregate from two comparable perylenediimide (PDI) dyads ( PEP and PBP ). The criss‐cross PEP ‐ PBP dimers in solution and ( PBP ‐ PEP )‐( PEP ‐ PBP ) tetramers in the solid state are well elucidated using single‐crystal X‐ray diffraction, dynamic light scattering, and diffusion‐ordered NMR spectroscopy. Extensive π–π stacking between the PDI units of PEP and PBP as well as repulsive interactions of swallow‐tailed alkyl substituents are responsible for the selective formation of discrete dimer and tetramer stacks. Our results reveal a new approach to preparing discrete π stacks that are appealing for making assemblies with well‐defined optoelectronic properties.     

Controlled Self-Assembly of Metallacycle-Bridged Gold Nanoparticles for Surface-Enhanced Raman Scattering

In this work, well-defined two-dimensional metallacycles have been successfully employed for the well-controlled self-assembly of gold nanoparticles (AuNPs) into discrete clusters such as dimers, trimers, tetramers, pentamers and even hexamers at the water–oil interface for the first time. Furthermore, the modular construction of metallacycle molecules allows precise control of spacing between the gold nanoparticles. Interestingly, it was found that interparticle spacing below 5 nm created by molecular metallacycles in the resultant discrete gold nanoparticle clusters led to a strong plasmon coupling, thus inducing great field enhancement inside the gap between the NPs. More importantly, different discrete clusters with precise interparticle spacing provide a well-defined system for studying the hot-spot phenomenon in surface-enhanced Raman scattering (SERS); this revealed that the SERS effects were closely related to the interparticle spacing.     

Analysis of droplet behavior in a de-oiling hydrocyclone

A mechanical separation process in a de-oiling hydrocyclone is described in which disperse oil droplets are separated from a continuous water phase. This separation process is influenced by droplet breakage and coalescence. Based on experimental data and simulation results in a stirred tank, a modified breakage model, which can be applied to droplet breakage in the de-oiling hydrocyclone, is developed. Then, a simulation model is developed coupling the numerical solution of the flow field in the hydrocyclone based on computational fluid dynamics (CFD) with population balances. The homogenous discrete method and the inhomogeneous discrete method are applied for solving the population balance model (PBM). The investigations show that the numerical results obtained by the simulation model coupled with the modified PBM using the inhomogeneous discrete method are in good accordance with experimental data under a high flow rate. According to this simulation model, the effect of three different inlet designs on the separation efficiency of the de-oiling hydrocyclone has been discussed. The results indicate that the separation efficiency of the de-oiling hydrocyclone can be improved with an appropriate inlet design.