浸渍碱密度在线监控

浸渍碱溶液浓度是化纤行业的一个重要质量指标,我国化纤工业生产过程自动化装备水平普遍不高,基本停留在离线分析、手工调整、经验控制阶段,导致企业生产效率低、资源消耗大、质量不稳定,制约着化纤工业的发展。为解决上述问题,在粘胶生产制备过程中,通过应用密度仪将碱液密度信息传输给生产控制人员和自动化设备,从而达到准确监测碱液密度的良好效果。

水滑石型固体碱碱性位的内标CO2-程序升温脱附-MS表征

通过共沉淀法制备了一系列不同镁铝比的水滑石样品,依据物相分析与热失重实验结果确认了合成的样品具有水滑石结构。以方解石型CaCO3为内标,对水滑石样品碱性位的CO2-程序升温脱附(TPD)定量表征进行校正,并比较了不同实验参数对方法精密度的影响。经过各测试参数的敏感性分析证实,用CaCO3脱附峰面积校正后,水滑石碱密度测量结果的RSD分别由9.7%、12.3%下降为4.3%、7.3%,而汇总分析的RSD可从29.6%下降至6.6%。CO2-TPD定量分析精密度明显提高,证实了内标法的优势及其应用于固体碱定量表征的可行性。将内标法所得结果与固体碱催化酯交换反应的性能关联,结果发现,水滑石催化性能受到活性相的碱强度与碱密度双重指标的调控,碱强度和碱密度越大,酯交换催化效率越高。

DFT Study of Alkali Metal Atom Adsorption on Defect-Free MgO（001）Surface

The adsorption of isolated alkali metal atoms （Li, Na, K, Rb, and Cs） on defect-free sur- face of MgO（001） has been systemically investigated with density functional theory using a pseudopotential plane-wave approach. The adsorption energy calculated is about -0.72 eV for the lithium on top of the surface O site and about one third of this value for the other alkali metals. The relatively strong interaction of Li with the surface O can be explained by a more covalent bonding involved, evidenced by results of both the projected density of states and the charge density difference. The bonding mechanism is discussed in detail for all alkali metals.

Effect of planting density on plant growth and camptothecin content of Camptotheca acuminata seedlings

C. acuminata seedlings cultivated in greenhouse were transplanted into the fields with 5 designed planting densities (11, 16, 25,44 and 100 plants·m^-2) in May of 2004 and were harvested in the middle of September of 2004. The seedling growth indexes including plant height and crown width, biomass allocation, camptothecin (CPT) content and CPT yield of different organs (young leaf, old leaf, stem,and root) were studied. For the 5 selected planting densities, the plant biomass, height, crown width, and total leaf area of C. acuminata seedlings all showed highest values at the planting density of 25 plants ·m^-2. CPT content in young leaves was higher than that in other organs of seedlings and presented an obvious change with the variation of planting densities and with the highest value at density of 100plants·m-2, while for other organs no significant variation in CPT content was found with change of planting density. The accumulation of CPT was enhanced significantly at the planting density of 25 plants·m^-2. It is concluded that for the purpose to get raw materials with more CPT from C. acuminata, the optimal planting density of C. acuminata seedlings should be designed as 25 plants·m^-2.

Facilitating active species by decorating CeO_(2)on Ni_(3)S_(2)nanosheets for efficient water oxidation electrocatalysis

In the pursuit of stable,high performance Ni-based oxygen evolution reaction(OER)electrocatalysts,modifying the local chemical compositions or fabricating hybrid nanostructures to generate abundant interfaces for improving the water oxidation activity of electrocatalysts has emerged as an effective strategy.Herein,we report the facile development of a Ni_(3)S_(2)-CeO_(2)hybrid nanostructure via an electrodeposition method.Benefiting from the strong interfacial interaction between Ni_(3)S_(2)and CeO_(2),the electron transfer is notably improved and the water oxidation activity of Ni_(3)S_(2)nanosheets is significantly enhanced.In 1.0 M KOH,the Ni_(3)S_(2)-CeO_(2)electrocatalyst achieves a current density of 20 mA cm-2 at a low overpotential of 264 mV,which is 92 mV lower than that of Ni_(3)S_(2).Moreover,Ni_(3)S_(2)-CeO_(2)exhibits superior electrochemical stability.Density functional theory calculations demonstrate that the enhanced OER electrocatalytic performance of Ni_(3)S_(2)-CeO_(2)can be ascribed to an increase in the binding strength of the reaction intermediates at the Ni_(3)S_(2)-CeO_(2)interface.

Effects of current density on preparation of grainy electrolytic manganese dioxide

Grainy electrolytic manganese dioxide was prepared by electrodeposition in a 0.9 mol/L MnSO4 and 2.5 mol/LH2SO4 solution. The structure, particle size and appearance of the grainy electrolytic manganese dioxide were determined by powder X-ray diffraction, laser particle size analysis and scanning electron micrographs measurements. Current density has important effects on cell voltage, anodic current efficiency and particle size of the grainy electrolytic manganese dioxide, and the optimum current density is 30 A/dm2. The grainy electrolytic manganese dioxide electrodeposited under the optimum conditions consists of γ-MnO2 with an orthorhombic lattice structure; the grainy electrolytic manganese dioxide has a spherical or sphere-like appearance and a narrow particle size distribution with an average particle diameter of 7.237 μm.

Self-assembled three-dimensional carbon networks with accessorial Lewis base sites and variational electron characteristics as efficient oxygen reduction reaction catalysts for alkaline metal-air batteries

Heteroatom-doped carbon has been demonstrated to be one of the most promising non-noble metal catalysts with high catalytic activity and stability through the modification of the electronic and geometric structures.In this study,we develop a novel solvent method to prepare interconnected N,S co-doped three-dimensional（3D）carbon networks with tunable nanopores derived from an asso-ciated complex based on melamine and sodium dodecylbenzene sulfonate（SDBS）.After the intro-duction of silica templates and calcination,the catalyst exhibits 3D networks with interconnected 50-nm pores and partial graphitization.With the increase of the number of Lewis base sites caused by the N doping and change of the carbon charge and spin densities caused by the S doping,the designed N,S co-doped catalyst exhibits a similar electrochemical activity to that of the commercial 20-wt%Pt/C as an oxygen reduction reaction catalyst.In addition,in an aluminum-air battery,the proposed catalyst even outperforms the commercial 5-wt%Pt/C catalyst.Both interconnected porous structures and synergistic effects of N and S contribute to the superior catalytic perfor-mance.This study paves the way for the synthesis of various other N-doped and co-doped carbon materials as efficient catalysts in electrochemical energy applications.

Controllable synthesis of a self-assembled ultralow Ru,Ni-doped Fe_(2)O_(3) lily as a bifunctional electrocatalyst for large-current-density alkaline seawater electrolysis

Highly efficient and stable bifunctional electrocatalysts that can be used for large-current-density electrolysis of alkaline seawater are highly desirable for carbon-neutral economies,but their facile and controllable synthesis remains a challenge.Here,self-assembled ultralow Ru,Ni-doped Fe_(2)O_(3) with a lily shaped morphology was synthesized on iron foam(RuNi-Fe_(2)O_(3)/IF)via a facile one-step hydrothermal process,in which the intact lily shaped RuNi-Fe_(2)O_(3)/IF was obtained by adjusting the ratio of Ru/Ni.Benefitting from the Ru/Ni chemical substitution,the as-synthesized RuNi-Fe_(2)O_(3)/IF can act as free-standing dual-function electrodes that are applied to electrocatalysis for the hydrogen evolution(HER)and oxygen evolution reactions(OER)in 1.0 mol L^(-1) KOH,requiring an overpotential of 75.0 mV to drive 100 mA cm^(-2) for HER and 329.0 mV for OER.Moreover,the overall water splitting catalyzed by RuNi-Fe_(2)O_(3)/IF only demands ultralow cell voltages of 1.66 and 1.73 V to drive 100 mA cm^(-2) in 1.0 mol L^(-1) KOH and 1.0 mol L^(-1) KOH seawater electrolytes,respectively.The electrodes show remarkable long-term durability,maintaining current densities exceeding 100 mA cm^(-2) for more than 100 h and thus outperforming the two-electrode system composed of noble catalysts.This work provides an efficient,economical method to synthesize self-standing bifunctional electrodes for large-current-density alkaline seawater electrolysis,which is of significant importance for ecological protection and energy exploitation.

A Theoretical Study on the Interactions of Crown Tetraalanylpeptide with Small Metal Cations

The density functional theory based on hybrid-method B3LYP was used to investigate the interaction of the alkaline-earth cations or alkali cations with crown tetraalanylpeptide which was the coronary structures of homothetic cyclotetraalapeptide and was represented as the model basic. Many properties including binding energy, optimum geometry structures and population analysis were calculated. It was shown that there was little change on the coronary structure before and after C4-AIa combination with small I A or ｜I A cations, and the electrons moved from C4-AIa to alkaline-earth cations or alkali cations during this process. Combination with C4-Ala, Be2~ was more predominant than Mg2~ and Ca2~ remarkably, but Li~ was not more predominant than Na＋ and K＋. The distances between alkaline-earth cations and the center of C4-Ala were 0.000 nm, 0.150 nm and 0.225 nm, respectively, when the binding energy at minimum, and that for alkali cations were 0.225 nm, 0.250 nm and 0.300 nm.

Anharmonic Vibrational Signatures of DNA Bases and Watson-Crick Base Pairs

Changes of molecular structure and associated charge distributions, and changes of anharmonic vibrational parameters from DNA base monomers to the Watson-Crick base pairs, have been investigated at the density functional theory level. Through examination of the NH2, N H, and C=O stretching vibrational modes that are involved in the multiple H-bonds in the base pairs, sensitivity of their diagonal and off-diagonal anharmonicities, as well as anharmonic vibrational couplings, to the structure change are predicted. Our results reveal the intrinsic connection between the anharmonic vibrational potentials, H-bonding, and electrostatic interactions in DNA bases.

Pros and Cons in Therapeutic Evaluation of Paraoxonase 1 in Nerve Agent Toxicity

PON 1 （Paraoxonase 1） has been proposed as an efficient catalytic bioscavenger to combat against OP （organophosphate） and CWNA （chemical warfare nerve agent） toxicity. Unlike stoichiometric bioscavengers such as butyrylcholinesterase, catalytic bioscavengers are cost effective with the advantage of eliminating all the OPs/CWNAs at low doses. Analysis of catalytic bioscavenger efficacy of PONI showed promising results by various group of researchers. Still, there are large numbers of grey areas which are not addressed so far. One of the major areas of interest is the pharmacokinetic analysis of infused PON 1 in multiple animal models. It is shown that previous studies in mice significantly increased half-life of PONI, while recent studies in guinea pigs from our group showed reduced half-life of PON1. Similar results were reported by other research groups in guinea pigs and non-human primates. The short half-life of exogenously administered PON1 in multiple animal models may be due to poor association of PON1 with its endogenous carrier, high density lipoprotein or lower doses of PON 1 or a reflection of species difference. These observations warrant the significance of thorough pharmacokinetic analysis of infused PON 1 and the development of alternative approaches for successful utility of PON 1 as an efficient medical countermeasure against OP/CWNA toxicity.

Berberine promotes the development of atherosclerosis and foam cell formation by inducing scavenger receptor A expression in macrophage

Berberine is identified to lower the serum cholesterol level in human and hamster through the induction of low density lipoproteins （LDL） receptor in hepatic cells. To evaluate its potential in preventing atherosclerosis, the effect of berberine on atherosclerosis development in apolipoprotcin E-deficient （apoE^-/-） mice was investigated. In apoE^-/- mice, berberine induced in rivo foam cell formation and promoted atheroselerosis development. The foam cell formation induced by berberinc was also observed in mouse RAW264.7 cells, as well as in mouse and human primary macrophages. By inducing scavenger receptor A （SR-A） expression in macrophages, berberine increased the uptake of modified LDL （DiO-Ac-LDL）. Bcrberine-induced SR-A expression was also observed in macrophage foam cells in vivo and in the cells at atherosclerotic lesion. Analysis in RAW264.7 cells indicated that berberine induced SR-A expression by suppressing PTEN expression, which led to sustained Akt activation. Our results suggest that to evaluate the potential of a cholesterol-reducing compound in alleviating atherosclerosis, its effect on the ceils involved in atherosclerosis development, such as macrophages, should also be considered. Promotion of foam cell formation could counter-balance the beneficial effect of lowering serum cholesterol.

Density function theory study on the interaction between camptothecin and cytosine

Density function M06 method has been used to optimize the geometries of camptothecin-cytosine at 6-3 I＋G＊ basis. Finally, thirteen stabilized complexes have been obtained. Theories of atoms in molecules （AIM） and natural bond orbital （NBO） have been utilized to investigate the hydrogen bonds involved in all the complexes. The interaction energies of all the complexes are corrected by basis set superposition error （BSSE）. By the analysis of complexes interaction energy, charge density, second- order interaction energies E（2）; it is indicated that the complex 6 is the most stable structure.

First Principles Study on Encapsulation of Alkali Metals into ZnO Nanocage

Encapsulation of alkali metals （Li, Na, K, and Rb） into Zn12O12 nanocage has been inves- tigated using density functional theory. Encapsulation of Li and Na atoms is found to be thermodynamically favorable at 298 K and 100 kPa, with negative Gibbs free energy change AG of about -130.12 and -68.43 kJ/mol, respectively. By increasing the size of encapsu- lated atom the process become less favorable so that in the cases of K and Rb encapsulations the AG values are positive. The results indicate that the LUMO, Fermi level, and specially HOMO of the cluster are shifted to higher energies so that the HOMO-LUMO gap of the cluster is significantly narrowed in all the cases. After encapsulation of the alkali metals the work function of cluster is decreased due to the shift of the Fermi level to higher energies. Therefore, the emitted electron current density from the Zn12O12 cluster will be increased.

Application of the HSAB principle for the quantitative analysis of nucleophilicity/basicity of organic compounds with lone-pair electrons

Based on the density functional theory,we described here a method to investigate the quantitative relationship between nucleophilicity/basicity and HSAB-theory-based properties of compounds with lone-pair electrons.Descriptors including global softness,Fukui function,local softness and local mulliken charge were calculated at SVWN/DN~* level of DFT with PC Spartan Pro.Nucleophilicity and basicity of 28 selected compounds were classified based on intensity.BP algorithm of artificial neural network(ANN) was employed to study the relationship between the descriptors and nucleophilicity/basicity.Cross-validation was carried out to avoid the over-fitting in training of ANN.A BP network was trained to quantify the relationship between HSAB-theory-based properties and nucleophilicity/basicity of compounds with lone-pair electrons.The results show that the prediction based on the network matches with the experimental results well.The local softness and Fukui function have a better relationship with nucleophilicity and local mulliken charge than with the basicity.The trained BP network could be utilized for predicting the nucleophilicity/basicity of compounds or functional groups with lone-pair electrons.

Highly efficient oxygen evolution and stable water splitting by coupling NiFe LDH with metal phosphides

It is a great challenge to develop highly active oxygen evolution reaction(OER)electrocatalysts with superior durability.In this study,a NiFe layered double hydroxidedecorated phosphide(NiFe LDH@CoP/NiP_(3))was constructed to display satisfactory OER activity and good stability for water splitting in alkaline media.At an overpotential of 300 mV,NiFe LDH@CoP/NiP_(3) achieved a current density of 82 mA cm^(-2) for the OER,which was 9.1 and 2.3 times that of CoP/NiP_(3) and NiFe LDH,respectively.Moreover,the reconstruction behavior,during which oxyhydroxides formed,was studied by a combination of X-ray photoelectron spectroscopy,Raman spectroscopy,and scanning electron microscopy.A synergistic effect between NiFe LDH and CoP/NiP_(3) was also observed for the hydrogen evolution reaction.Furthermore,when NiFe LDH@CoP/NiP_(3) acted as both the cathode and anode for overall water splitting,a high current density of 100 mA cm^(-2) was maintained for more than 275 h.In addition,under Xe light irradiation,a solar-to-hydrogen efficiency of 9.89% was achieved for solar-driven water splitting.This work presents the coupling of different active compositions,and can provide a reference for designing bifunctional electrocatalysts.

Ternary PtRuTe alloy nanofibers as an efficient and durable electrocatalyst for hydrogen oxidation reaction in alkaline media

Sluggish kinetics of anodic hydrogen oxidation reaction(HOR)in alkaline media,which arises from the two orders of magnitude lower HOR activity in alkali than that in acid media for platinum group metals,hinders the commercial implementation of anion exchange membrane fuel cells(AEMFCs).Consequently,the development of platinum-based catalysts combined with high efficiency and durability is urgently required.Herein,we report a facile route for the synthesis of ternary PtRuTe alloy nanofibers with Pt atomic ratio of only 11%via a simple galvanic replacement reaction.We optimize the adsorption strength of platinum and ruthenium towards hydrogen and hydroxyl species by regulating the electron donation from tellurium to platinum and ruthenium.Hence,the obtained trimetallic alloy catalyst exhibits an impressive kinetic current density of 30.6 mA cm^(−2)_(geo) at 50 mV and an exchange current density of 0.426 mA cm^(−2)_(metal),which shows 3.0-and 2.5-fold enhancement compared with the commercial Pt/C in alkaline electrolyte,respectively.Moreover,the catalyst also demonstrates excellent stability with merely 5%activity attenuation after 2000 potential cycles.This work offers new pathways to boost alkaline HOR by rationally designing multicomponent alloys.