低胶材钢筋混凝土碳化对钢筋锈蚀影响研究进展

在国家积极推进碳达峰、碳中和目标背景下,水泥混凝土行业减少碳排放势在必行。文中重点综述了低水泥用量高掺合料对混凝土碳化行为的影响机理研究现状,涉及碳化行为对混凝土内部钢筋锈蚀的影响机理、混凝土内部钢筋锈蚀的评价方法及优缺点,并指明了进一步的研究方向,这对于改善高掺合料钢筋混凝土耐久性和降低建筑行业碳排放具有重要意义。

Characterization of Embryonic Stages through Variations in the Egg＇s Contents in Spodoptera fitura

This paper describes the embryonic development of the common cutworm Spodoptera litura （Fabricius） （Lepidoptera： Noctuidae） which is divided into eight embryonic stages, through variations in the egg＇s contents. Experiments were conducted on the eggs ofS. litura under laboratory conditions. The highest concentration of the protein （min.-max.： 32-! 40 lag/egg） and the lowest of the carbohydrate （min.-max.： 3.0-44.0 lag/egg） were obtained; similarly, the DNA content was smaller （min.-max.： 1.0-38.2 lag/egg） than the RNA （min.-max.： 9.2-360.0 lag/egg） throughout the embryogenesis. Three peaks of ecdysteroid titre were observed which were responsible for appearance of particular events during embryogenesis. The last highest peak of 400_＋33.4 lag/egg was appeared at 84 h after oviposition when larva was ready to hatch. Therefore, it is concluded that eight embryonic stages in S. litura were characterized by fluctuation in the egg＇s contents, which were responsible for gradual-progressive embryonic development. The egg-larval development did not show a normal distribution of embryonic developmental-time.

Synthesis of Bisphenols Carrying Long Hydrocarbon Side Chains

Bisphenols containing long aliphatic hydrocarbon side chains were synthesized by the condensation of phenol with aldehyde or ketone in the presence of heteropolyacid. Their structures were characterized by IR, 1H NMR, 13C NMR and element analysis. The experiment results show that when heteropolyacid was used as a catalyst, these bisphenols were obtained in high selectivity and high yields.

Representation of phase behavior of associating fluids using EOS

Associating fluids containing water and alkanols show a strong non-ideal behaviour on thermodynamic properties Simple cubic equations of state （EOS）. such as the Peng-Robinson （PR） equation, with conventional mixing rules are popular lbr its simplicity and eas3＇ implementation. However it is incapable of reliably representing the phase behaviour of associating mixtures. An effort has been made in this study to develop a new model in which the non-densit3＇-dependent mixing rules are applied to the PR EOS to represent the phase behaviour of associating fluids. The proposed model takes into account of the polarity in the attractive term of the EOS by including both the conventional random mixing term and the asymmetric interaction term. The proposed model has been successfully applied to the calculation of the vapor-liquid equilibrium （VLE） and liquid-liquid equilibrium （LLE） of fluids containing water, alkanols, acid gases, and hydrocarbons. A satisfactory agreement between the predictions of the proposed model and the experimental data in the literature is reached.

Characterization of foreign grain on 6H-SiC facet

6H-SiC single crystals were grown by sublimation method. It is found that foreign grains occur frequently on the facets of the crystals. To characterize the foreign grain, a longitudinal and a sectional cut samples were prepared by standard mechanical processing method. Raman spectrum confirms that the foreign grain is actually a mis-oriented 6H-SiC grain. The surface structure of the foreign grain was studied by chemical etching and optical microscopy. It is shown that etch pits in foreign grain region take the shape of isosceles triangle, which are different from those in mono-crystalline region, and high density stacking faults are observed on the surface of the foreign grain. The orientation of foreign grain surface is determined to be （10]-4） plane by back-scattering X-ray Laue image. The X-ray powder diffraction reveals that the powder is partly graphitized after a long crystal growth rim. Therefore it is believed that the loss of Si results in the formation of C inclusions, which is responsible for the nucleation of foreign grain in the facet region.

Synthesis and Characterization of Cobalt-Carbon Core-Shell Microspheres in Supercritical Carbon Dioxide System

The synthesis of cobalt-carbon core-shell microspheres in supercritical carbon dioxide system was investi- gated. Cobalt-carbon core-shell microspheres with diameter of about 1μm were prepared at 350 ℃ for 12 h in a closed vessel containing an appropriate amount of bis（cyclopentadienyl）cobalt powder and dry ice. Characterization by a variety of techniques, including X-ray powder diffraction, X-ray photoelectron spectroscopy, TransmissiOn electron microscope, Fourier transform infrared spectrum and Raman spectroscopy analysis reveals that each cobalt-carbon core-shell microsphere is made up of an amorphous cobalt core with diameter less than 1 μm and an amorphous carbon shell with thickness of about 200 nm. The possible growth mechanism of cobalt-carbon core-shell microspheres is discussed, based on the pyrolysis of bis（cyclopentadienyl）cobalt in supercritical carbon dioxide and the deposition of carbon or carbon clusters with odd electrons on the surface of magnetic cobalt cores due to magnetic attraction. Magnetic measurements show 141.41 emu/g of saturation magnetization of a typical sample, which is lower than the 168 emu/g of the corresponding metal cobalt bulk material. This is attributed to the considerable mass of the carbon shell and amorphous nature of the magnetic core. Control of magnetism in the cobalt-carbon core-shell microspheres was achieved by annealing treatments.

Synthesis and TEM structural characterization of C60-flattened carbon nanotube nanopeapods

A fully flattened carbon nanotube （FNT）, a graphene nanoribbon （GNR） analogue, provides a hollow space at edges for endohedral doping. Due to the unique shape of the hollow space of FNTs, novel types of low-dimensional arrangements of atoms and molecules can be obtained through endohedral doping into FNTs, which provides a new type of nanopeapods. FNT-based nanopeapods have been synthesized through endohedral doping of C60, and their structural characterization with transmission electron microscopy （TEM） performed. The doping of C60 into the inner hollow space of FNTs has been carried out via the gas-phase filling method, where open-ended FNTs are sealed in a glass ampoule and heated at 723-773 K for two days. TEM observations show that most of the encapsulated C60 molecules align as single molecular chains along the edges of FNTs and that some of the C60 forms two-dimensional close-packed structures inside FNTs.