取代聚苯乙炔环状三聚体的合成

以对溴苯酚为原料,经四步反应合成一种取代苯乙炔单体4-乙炔基-(2,6)二羟甲基-1-十二烷基酚醚。利用手性的铑催化剂引发聚合,得到高分子量的螺旋聚合物,通过GPC和CD对分子量和螺旋结构进行表征。最后通过光环化反应高效合成了环状三聚体,并通过1HNMR和GPC确认其化合物结构。     

Mass transfer and holdup in gas-liquid cocurrent flow packed beds containing water-repellent particles

Water-repellent particles were prepared by spraying polytetrafluoroethylene (PTFE) on activated carbon. Gas-liquid volumetric mass transfer coefficient and holdup were determined in gas-liquid cocurrent upflow and downflow packed beds from the measurements of gas desorption and volume, respectively. As the PTFE loading increased, the gas-liquid volumetric mass transfer coefficients in both upflow and downflow modes were enhanced. Gas holdup in the upflow mode increased with the PTFE loading, while the dynamic liquid holdup in the downflow mode decreased. The enhancement of the mass transfer rate from gas to liquid can be explained by the effect of water-repellency on the surface of activated carbon.     

Profiling and Imaging of Phospholipids in Brains of Abcd1‐Deficient Mice

ABCD1 is a gene responsible for X‐linked adrenoleukodystrophy (X‐ALD), and is critical for the transport of very long‐chain fatty acids (VLCFA) into peroxisomes and subsequent β‐oxidation. VLCFA‐containing lipids accumulate in X‐ALD patients, although the effect of ABCD1‐deficiency on each lipid species in the central nervous system has not been fully characterized. In this study, each phospholipid and lysophospholipid species in Abcd1‐deficient mice brains were profiled by liquid chromatography‐mass spectrometry. Among the phospholipid and lysophospholipid species that are significantly more enriched in Abcd1‐deficient mice brains, VLCFA were present in 75, 15, 5, 4, and 1 species of phosphatidylcholine, phosphatidylethanolamine, sphingomyelin, lysophosphatidylcholine, and lysophosphatidylethanolamine, respectively. Most VLCFA were incorporated at the sn‐1 position of phosphatidylcholine and phosphatidylethanolamine. Among the phospholipid species that are significantly less enriched in Abcd1‐deficient mice brains, odd‐numbered saturated or mono‐unsaturated fatty acyl moieties are contained in all phosphatidylcholine species. In addition, a number of phosphatidylglycerol, phosphatidylinositol, and phosphatidylserine species contained highly unsaturated fatty acyl moieties. Intriguingly, 44:1 phosphatidylcholine with VLCFA was mainly distributed in the gray matter, such as the cortex, but not in the white matter in the cerebrum and cerebellum. These results show that ABCD1‐deficiency causes metabolic alternation of long‐chain fatty acids and VLCFA. Moreover, our results imply a molecular mechanism for the incorporation of saturated or monounsaturated VLCFA into the sn‐1 position of phospholipids, and also indicate that the distribution of phospholipids with VLCFA may correlate with the development of X‐ALD.     

Current distribution in a two-dimensional narrow gap cell composed of a gas evolving electrode with an open part

On the basis of the observation of gas bubbles evolved by electrolysis, a two-dimensional vertical model cell composed of electrodes with open parts for releasing gas bubbles to the back side is proposed. The model cell consists of two layers. One layer forms a bubble curtain with a maximum volume fraction of gas bubbles in the vicinity of the working electrode with open parts. The other. being located out of the bubble layer, is a convection layer with a small volume fraction distributed in the vertical direction under forced convection conditions. The cell resistance and the current distribution were computed by the finite element method when resistivity in the back side varied in the vertical direction along the cell. The following three cases for overpotential were considered: no overpotential, overpotential of the linear type and overpotential of the Butler-Volmer type. It was found that the cell resistance was determined not only by the interelectrode gap but also by the percentage of open area and in some cases by the superficial surface area. The cell resistance varied only slightly with the distribution of the bubble layer in the back side.Nomenclature b linear overpotential coefficient given byb=/i - C proportionality constant given by Equation 15 - d ₁ distance between front side of working electrode and separator - d ₂ thickness of separator - F Faraday constant - I total current per half pitch - i current density at working electrode - i ₀ exchange current density - L length of a real electrolysis cell - n number of electrons transferred in electrode reaction - O _p percentage of open area given by Equation 1 - p pitch, i.e. twice the length of the unit cell, defined by 2(BC) in Fig. 4 - q thickness of bubble curtain, defined by (AM) in Fig. 4 - R gas constant - r _t total cell resistance - r unit-cell resistance defined by (V – V _eq)/I - r _rs residue ofr from sum ofr ₀ andr - r ₀ ohmic resistance of solution when0 _p=0 - r resistance due to overpotential when0 _p=0 - s electrode surface ratio or superficial surface area given by Equation 2 for the present model - T absolute temperature - t thickness of working electrode defined by EF in Fig. 4 - V cell voltage - V _eq open circuit potential difference between working and counter electrodes - solution velocity in cell - ₀ solution velocity at bottom of cell - w width of working electrode, defined by 2(DE) in Fig. 4 - x abscissa located on cell model - y ordinate located on cell model - anodic transfer coefficient - linear overpotential kinetic parameter defined byb/[_bc(p/2)] - d infinitesimally small length on the boundary - volume fraction of gas bubbles in cell - dimensionless cell voltage defined bynF(V – V _eq)/RT - overpotential at working electrode - Butler-Volmer overpotential kinetic parameter defined by [nFi _0bc(p/2)]/RT - coordinate perpendicular to boundary of model cell - ₁ resistivity of bubble-free solution - ₂ resistivity of separator - _bc resistivity of bubble curtain - potential in cell     

Effects of calcining conditions of kaolinite on pore structures of mesoporous materials prepared by the selective leaching of calcined kaolinite

This paper describes the effects of calcining conditions of kaolinite on pore structures of the porous materials obtained from the selective leaching of calcined kaolinite using KOH solution. Mesoporous -Al₂O₃ was the predominant crystalline phase in the samples calcined in the temperature range between 950°C and 1050°C for 24 h. The mean specific surface area of these samples was approximately 250 m² · g^–1 and the mean total pore volume was approximately 0.8 ml · g^–1. The pore size distribution curves of these samples showed a sharp peak at around 2–3 nm pore radius. This peak was sharper for the sample calcined at 1000°C for 24 h. On the other hand, the pore sizes of the sample calcined at 1100°C for 24 h increased abruptly to 10–20 nm and this change corresponded to the formation of mullite in the sample. The pore sizes of the samples calcined at 1100°C varied with calcining time. The specific surface area and total pore volume decreased, the longer the calcining time of the samples, and this was correlated with an increase in the amount of mullite in the samples.     

Synthesis of stable and soluble one-handed helical poly(substituted acetylene)s without chiral pendant groups via polymer reaction in membrane state

A soluble and stable one-handed helical conjugated polymer without the coexistence of any other chiral moieties was successfully synthesized by asymmetric-induced polymerization of a chiral monomer having two hydroxyl groups followed by desubstitution of the chiral groups in a solid membrane state. The reason for the success was the polymer reaction was carried out in the membrane state. This is an alternative method to obtain such a unique chiral polymer which was obtained only by the helix-sense-selective polymerization (HSSP) we reported before. In addition the efficiency of the chiral induction was higher than that of the HSSP. It is interesting that the “Membrane state” acted like as if a protecting group.     

Study of crater formation and sputtering process with large gas cluster impact by molecular dynamics simulations

Molecular dynamics (MD) simulations of large argon clusters impacting on silicon solid targets were performed in order to study the transient process of crater formation and sputtering. The MD simulations demonstrate that the initial momentum of incident cluster is transferred to target surface atoms through multiple collision mechanism, where the initial momentum, which is along to the surface normal before impact, is deflected to lateral direction. This momentum transfer process was analyzed by the calculation of the velocity at the crater edge (the interface between cluster and target). In the case of Ar₁₀₀₀ cluster impact on Si(1 0 0) target at low energy per atom less than 40 eV/atom, the maximum value of lateral velocity of the crater edge increases in proportional to the velocity of incident cluster atoms. On the other hand, the crater edge velocity saturates over 40 eV/atom of incident energy per atom. In this case, the whole of constituent cluster atoms are implanted into the target and expand in both lateral and reflective directions at the subsurface region of the target. These MD simulations demonstrated that this collisional process result in the high yield sputtering of the target atoms.     

Supplementation of the diet of dairy cows with trehalose results in milk with low lipid peroxide and high antioxidant content

The objective of this study was to investigate the effect of dietary supplementation with the disaccharides trehalose and cellobiose on antioxidant activity in rumen fluid, blood, and milk of dairy cows. Nine Holstein dairy cows housed in a free-stall barn were divided into 3 groups, with each group receiving a different dietary treatment (a control diet, a 1% trehalose-supplemented diet, or a 1% cellobiose-supplemented diet) following a 3 × 3 Latin square design. Feed intake and milk production increased in cows receiving the trehalose-supplemented diet compared with those receiving the control and cellobiose-supplemented diets. The total protozoa numbers in the rumen fluid of cows fed trehalose- or cellobiose-supplemented diets were greater than those of the control group. The C18:0 and C18:1 fatty acid content was increased in the milk of cows fed the trehalose-supplemented diet compared with that of the control group, and the C18:3n-3 fatty acid content in the milk of cows fed the cellobiose-supplemented diet was less than that of the control group. Plasma biochemical parameters were unchanged among the different treatments. In rumen fluid, 1,1-diphenyl-2-picrylhydrazyl radical scavenging activity and superoxide dismutase activity were increased 2 h after feeding in cows receiving the cellobiose-supplemented diet compared with the control group, and the concentration of thiobarbituric acid reactive substances in the rumen fluid of cows fed the cellobiose-supplemented diet was decreased. In contrast, the values of these parameters measured in the milk of cows fed the cellobiose-supplemented diet were no different from those of control cows. Dietary supplementation with trehalose did, however, bring about an improvement of the oxidative status of milk and blood in these animals compared with controls. These results provide the first evidence supporting the use of dietary disaccharides to decrease lipid peroxide levels and increase the antioxidant content of dairy cow milk. The findings suggest that disaccharides, particularly trehalose, might be useful as supplements for reducing oxidative stress and improving the quality of milk for human consumption, as well as possibly impairing the processes that give rise to lipid oxidation odor in dairy cow milk.     

Efficient synthesis and magnetic properties of triphenylamine bearing three nitronylnitroxide radicals

Improved synthesis and reinvestigation of the magnetic properties of triphenylamine bearing three nitronylnitroxide radicals (1) were carried out. Single crystal X-ray crystallographic analysis of 1 established that its molecular shape had a C₃-symmetry. Our newly prepared 1 showed different physical properties from those of reported. SQUID measurements of 1 showed that each of the three spins of 1 behaved independently at room temperature. In contrast, the three spins coupled antiferromagnetically at lower temperature as low as ca. 1.8 K. These spin behaviors can be explained by a regular triangular antiferromagnetic model (J/k_B = ?3.3 K) and interpreted as a spin frustration system.