A qualitative H NMR study of CHCl3 adsorption on conjugated acid–base pairs in cation exchanged Y-zeolites

Solution state ¹H NMR is employed to study the mode and strength of chloroform adsorption on conjugated acid–base pairs of cation-exchanged Y-zeolites. ¹H NMR results indicate that two different surface bonding orientations may exist. An acidic hydrogen site of zeolite favours orientation where the chloroform hydrogen points towards the zeolite cage centre. An exchanged electropositive cation increases the basicity of framework oxygens of zeolite and directs the chloroform to adsorb on framework oxygens with a hydrogen bond. In this adsorption site the chemical shift of the chloroform hydrogen has a linear dependence on the electronegativity of the cation.     

四氯乙烯改性炭黑在橡胶中的分散速度及硫化胶性能影响的研究

应用四氯乙烯对炭黑进行热机械方法处理后，由于四氯乙烯对炭黑粒子起到了表面活化作用和氯原子的空间位阻效应，降低了炭黑粒子间的内聚能，在混炼时提高了炭黑在橡胶中的分散速度，缩短了混炼时间，增多了橡胶大分子链与炭黑粒子间的化学结合点，从而提高了硫化胶的定伸强度、硬度等综合性能。     

非氧化物玻璃形成能力的化学键方法

本文采用化学键方法对卤化物及硫卤玻璃的化学键特性进行了探讨。所有的玻璃组成均可分为3类：硬质玻璃组分,如氟化物;软质玻璃组分,如溴化物、碘化物、硫系化物;中间玻璃组分,如氯化物。具有高正电荷,小离子半径的阳离子适合形成硬质玻璃,而那些低氧化态、大离子半径的阳离子则适合于形成软质玻璃。导致硬质玻璃组分与软质玻璃组分具有不同“赠-受”键的原因是这两种玻璃组分具有不同的聚合机理,玻璃结构中簇间化学键力平衡和热能(温度)平衡也得到了讨论。     

氢键对物质性质与化学反应的广泛影响

氢键是一种特殊的化学键合形式,在很多物质体系中存在着广泛的影响.在无机化学、有机化学、分析化学、生物化学、高分子材料等领域中,氢键都显现了特殊的重要性.讨论了氢键对物质的物理性质、酸碱性、物质结构与化学反应等方面的影响.     

镁合金黑色化学转化膜工艺研究

通过正交试验,优化得出镁合金黑色化学转化膜最佳工艺配方参数。分析了各成分对镁合金黑色化学转化膜耐腐蚀性、附着强度的影响。     

Intrinsic hardness of boron carbide: Influence of polymorphism and stoichiometry

Boron carbide comprises of polymorphs that differ in crystallographic arrangement and stoichiometry. Consequently, specimens extracted from the same batch can exhibit variability in mechanical properties depending on the constituent mixture of polymorphs. In this work, density functional theory simulations and estimates from three models (bond resistance model, bond strength model, and electronegativity model) are utilized to (i) investigate the influence of polymorphism and stoichiometry on the intrinsic hardness of boron carbide, (ii) reveal the sensitivity of the estimates to the model used, and (iii) test their conformance to experimental data. The study finds intrinsic hardness of boron carbide to be primarily a function of stoichiometry, with polymorphism having a lower influence. Furthermore, hardness estimates are shown to exhibit substantial sensitivity to the model used, differing by as much as 9 GPa for the same polymorph. Thus, the search for new superhard materials should be guided by more than just one model. Our analysis finds bond resistance model to offer the best conformance to experimental data, indicating that bond length is a much stronger influencer of intrinsic hardness in covalent crystals than coordination numbers and electronegativities of bonding atoms.     

固相法化学降解等规聚丙烯

在剪切力作用和较低温度下,利用过氧化物对等规聚丙烯（PP）化学降解,得到了具有超高熔体流动速率（MFR）的PP降解产品。考察了降解时间对降解产品的MFR及相对分子质量的影响,发现随着降解时间的增加,MFR提高幅度逐渐减小,相对分子质量下降。用红外光谱和差示扫描量热法表征发现,降解PP出现了羰基和碳碳双键吸收峰．且羰基吸收峰随降解时间的增加而增强;PP降解产品在不同温度下的结晶结构未改变。     

The bondons: the quantum particles of the chemical bond

By employing the combined Bohmian quantum formalism with the U(1) and SU(2) gauge transformations of the non-relativistic wave-function and the relativistic spinor, within the Schrödinger and Dirac quantum pictures of electron motions, the existence of the chemical field is revealed along the associate bondon particle B̶ characterized by its mass (m_B̶), velocity (v_B̶), charge (e_B̶), and life-time (t_B̶). This is quantized either in ground or excited states of the chemical bond in terms of reduced Planck constant ħ, the bond energy E_bond and length X_bond, respectively. The mass-velocity-charge-time quaternion properties of bondons’ particles were used in discussing various paradigmatic types of chemical bond towards assessing their covalent, multiple bonding, metallic and ionic features. The bondonic picture was completed by discussing the relativistic charge and life-time (the actual zitterbewegung) problem, i.e., showing that the bondon equals the benchmark electronic charge through moving with almost light velocity. It carries negligible, although non-zero, mass in special bonding conditions and towards observable femtosecond life-time as the bonding length increases in the nanosystems and bonding energy decreases according with the bonding length-energy relationship Ebond[kcal/mol]×Xbond[A0]=182019, providing this way the predictive framework in which the B̶ particle may be observed. Finally, its role in establishing the virtual states in Raman scattering was also established.     

化学镀镍配方的优化及镀镍过程机理的研究

采用正交设计法,就化学镀镍的配方进行了分析和研究,并根据化学镀镍反应机理的电化学理论,揭示了化学镀镍磷合金实验过程的电化学本质。     

纳米Al2O3,ZnO,CeO2,ZrO2对低温无铅熔块性能的影响

采用正交实验法,研究了在无铅基础熔块中,添加纳米Al2O3,ZnO,CeO2,ZrO2对其抗弯强度、维氏硬度及化学稳定性等性能的影响。结果表明:外加纳米氧化铝等可使无铅熔块抗弯强度提高30%,化学稳定性提高60%～80%,硬度提高10%左右。     

新型铜合金化学去毛刺剂的研制

研制出一种新型铜合金化学去毛刺剂。先通过单因素试验确定各成分的最佳质量分数,再通过正交试验确定最佳配方,最后对化学去毛刺剂的各项性能进行测试。结果表明:该化学去毛刺剂的毛刺去除率、腐蚀率、稳定性等各项性能均能达标。     

Novel Abscisic Acid Antagonists Identified with Chemical Array Screening

Abscisic acid (ABA) signaling is involved in multiple processes in plants, such as water stress control and seed dormancy. Major regulators of ABA signaling are the PYR/PYL/RCAR family receptor proteins, group A protein phosphatases 2C (PP2Cs), and subclass III of SNF1‐related protein kinase 2 (SnRK2). Novel ABA agonists and antagonists to modulate the functions of these proteins would not only contribute to clarification of the signaling mechanisms but might also be used to improve crop yields. To obtain small molecules that interact with Arabidopsis ABA receptor PYR1, we screened 24 275 compounds from a chemical library at the RIKEN Natural Products Depository by using a chemical array platform. Subsequent SnRK2 and PP2C assays narrowed down the candidates to two molecules. One antagonized ABA in a competitive manner and inhibited the formation of the PYR1‐ABA‐PP2C ternary complex. These compounds might have potential as bioprobes to analyze ABA signaling.     

Efficient Synthesis of Peptide and Protein Functionalized Pyrrole-Imidazole Polyamides Using Native Chemical Ligation

The advancement of DNA-based bionanotechnology requires efficient strategies to functionalize DNA nanostructures in a specific manner with other biomolecules, most importantly peptides and proteins. Common DNA-functionalization methods rely on laborious and covalent conjugation between DNA and proteins or peptides. Pyrrole-imidazole (Py–Im) polyamides, based on natural minor groove DNA-binding small molecules, can bind to DNA in a sequence specific fashion. In this study, we explore the use of Py–Im polyamides for addressing proteins and peptides to DNA in a sequence specific and non-covalent manner. A generic synthetic approach based on native chemical ligation was established that allows efficient conjugation of both peptides and recombinant proteins to Py–Im polyamides. The effect of Py–Im polyamide conjugation on DNA binding was investigated by Surface Plasmon Resonance (SPR). Although the synthesis of different protein-Py–Im-polyamide conjugates was successful, attenuation of DNA affinity was observed, in particular for the protein-Py–Im-polyamide conjugates. The practical use of protein-Py–Im-polyamide conjugates for addressing DNA structures in an orthogonal but non-covalent manner, therefore, remains to be established.     

Chemical Reactions Between Dentin and Bonding Agents

The possible interaction between dentin and a proprietary dentin bonding agent (DBA), Gluma, was studied by Phase Photoacoustic FTIR. The determination of the existence and nature of a chemical bond between the DBA and the substrate can be of great importance in explaining the performance of these agents. Human dentin was treated by solutions of 2-hydroxyethyl methacrylate (HEMA), glutaraldehyde and a combination of both (Gluma Primer). Spectra of dentin samples treated with 35% and 100% HEMA as well as Gluma Primer show loss of both the hydroxyl (O-H stretch) and methylene (CH₂ stretches) peaks from HEMA while other peaks are retained, even after thorough washing. This indicates a reaction between HEMA and the collagenous fraction of dentin.     

Structural,Electronic Properties,Hydrogen Bonding Analyses,and Biological Activity of Two Multiple Myeloma Drugs: Lenalidomide and Pomalidomide

In this article, we made a comparative study of two multiple myeloma drugs: lenalidomide and pomalidomide. We calculated and discussed their geometries at DFT/B3LYP method. Intra-molecular hydrogen bonding in these molecules is confirmed and characterized by QTAIM calculations. Electronic parameters along with HOMO-LUMO and MESP surfaces are calculated in order to compare their chemical reactivity. The effect of structure and bonding on electronic properties and biological activities is discussed and it is established that pomalidomide is more biologically active than lenalidomide. The phenyl ring of these molecules show teratogenic effects, making a possibility of finding another new class of drugs.     

Perfluorocarbons in Chemical Biology

Perfluorocarbons, saturated carbon chains in which all the hydrogen atoms are replaced with fluorine, form a separate phase from both organic and aqueous solutions. Though perfluorinated compounds are not found in living systems, they can be used to modify biomolecules to confer orthogonal behavior within natural systems, such as improved stability, engineered assembly, and cell-permeability. Perfluorinated groups also provide handles for purification, mass spectrometry, and ¹⁹F NMR studies in complex environments. Herein, we describe how the unique properties of perfluorocarbons have been employed to understand and manipulate biological systems.     

化工装置设计中的通道与空间设计探讨

介绍通道与空间在化工设计中的重要性,体现在安装、操作、维修等方面以人身与财产安全为根本目的。结合化工设计实例进行介绍、分析与探讨,并对通道与空间设计的流程提出了自己的看法：＂结合条件、逐一分析、安全第一、优化组合＂。     

Chemical Bonding: The Orthogonal Valence-Bond View

Chemical bonding is the stabilization of a molecular system by charge- and spin-reorganization processes in chemical reactions. These processes are said to be local, because the number of atoms involved is very small. With multi-configurational self-consistent field (MCSCF) wave functions, these processes can be calculated, but the local information is hidden by the delocalized molecular orbitals (MO) used to construct the wave functions. The transformation of such wave functions into valence bond (VB) wave functions, which are based on localized orbitals, reveals the hidden information; this transformation is called a VB reading of MCSCF wave functions. The two-electron VB wave functions describing the Lewis electron pair that connects two atoms are frequently called covalent or neutral, suggesting that these wave functions describe an electronic situation where two electrons are never located at the same atom; such electronic situations and the wave functions describing them are called ionic. When the distance between two atoms decreases, however, every covalent VB wave function composed of non-orthogonal atomic orbitals changes its character from neutral to ionic. However, this change in the character of conventional VB wave functions is hidden by its mathematical form. Orthogonal VB wave functions composed of orthonormalized orbitals never change their character. When localized fragment orbitals are used instead of atomic orbitals, one can decide which local information is revealed and which remains hidden. In this paper, we analyze four chemical reactions by transforming the MCSCF wave functions into orthogonal VB wave functions; we show how the reactions are influenced by changing the atoms involved or by changing their local symmetry. Using orthogonal instead of non-orthogonal orbitals is not just a technical issue; it also changes the interpretation, revealing the properties of wave functions that remain otherwise undetected.