Hydration and Expansion Characteristics of MgO Expansive Agent in Mass Concrete.

Based on the underground reinforced concrete wall of subway stations (Hangzhou, China), this paper studied the influence of a MgO expansive agent (MEA) on deformation and mechanical properties of a reinforced concrete wall. The results show that the effect of the MEA with different activities to compensate for the shrinkage of reinforced concrete walls is different. For MEA-R (60 s), because the activity is too high, its hydration rate is too fast, and many expansions occur at the plastic state of the concrete, which cannot effectively compensate for the shrinkage of concrete. For MEA-S (220 s), due to its low activity, the early hydration rate is so slow that it cannot compensate for the shrinkage, but it compensates well at the later stage due to the continuous hydration expansion of MEA. For MEA-M (140 s), the shrinkage of concrete is well compensated for the shrinkage at the early, middle and late stages due to its moderate activity. After using MEA to partially replace fly ash and mineral powder, the compressive strength of concrete was lower at the early stage (0-28 days). However, in the later stage, the porosity of concrete decreased rapidly, and the compressive strength of concrete would also be significantly improved. Therefore, choosing a suitably active MEA can compensate for the shrinkage of mass concrete without reducing its strength.

Effect of LiNO3 on Expansion of Alkali⁻Silica Reaction in Rock Prisms and Concrete Microbars Prepared by Sandstone.

The aim of this research is to investigate the effect of LiNO3 on the alkali⁻silica reaction (ASR) expansion of reactive sandstone and the mechanism through which this occurs. This paper presents the results from tests carried out on rock prisms and concrete microbars prepared by sandstone and LiNO3. The findings show that LiNO3 does not decrease the expansion of these samples unless the molar ratio of [Li]/[Na + K] exceeds 1.66, and the expansion is greatly increased when its concentration is below this critical concentration. The expansion stress test proves that Li2SiO3 is obviously expansive. X-ray diffraction (XRD) and scanning electron microscope (SEM) results indicate that LiNO3 reacts with the microcrystalline quartz inside sandstone, inhibiting the formation of ASR gel, and the formation of Li2SiO3 causes larger expansion. A high concentration of LiNO3 might inhibit the ASR reaction in the early stages, and the formation of Li2SiO3 causes expansion and cracks in concrete after a long period of time.

NMDA GluN2B receptors involved in the antidepressant effects of curcumin in the forced swim test.

The antidepressant-like effect of curcumin, a major active component of Curcuma longa, has been previously demonstrated in the forced swimming test. However, the mechanism of this beneficial effect on immobility scores, which is used to evaluate antidepressants, remains largely uncharacterized. The present study attempts to investigate the effects of curcumin on depressive-like behavior with a focus upon the possible contribution of N-methyl-D-aspartate (NMDA) subtype glutamate receptors in this antidepressant-like effect of curcumin. Male mice were pretreated with specific receptor antagonists to different NMDA receptor subtypes such as CPP, NVP-AAM077 and Ro25-6981 as well as to a partial NMDA receptor agonist, D-cycloserine (DCS), prior to administration of curcumin to observe the effects on depressive behavior as measured by immobility scores in the forced swim test. We found that pre-treatment of mice with CPP, a broad-spectrum competitive NMDA receptor antagonist, blocked the anti-immobility effect of curcumin, suggesting the involvement of the glutamate-NMDA receptors. While pretreatment with NVP-AAM077 (the GluN2A-preferring antagonist) did not affect the anti-immobility effect of curcumin, Ro25-6981 (the GluN2B-preferring antagonist) was found to prevent the effect of curcumin in the forced swimming test. Furthermore, pre-treatment with a sub-effective dose of DCS potentiated the anti-immobility effect of a sub-effective dose of curcumin in the forced swimming test. Taken together, these results suggest that curcumin shows antidepressant-like effects in mice and the activation of GluN2B-containing NMDARs is likely to play a predominate role in this beneficial effect. Therefore, the antidepressant-like effect of curcumin in the forced swim test may be mediated, at least in part, by the glutamatergic system.

Curcumin produces antidepressant effects via activating MAPK/ERK-dependent brain-derived neurotrophic factor expression in the amygdala of mice.

The potential antidepressant effects of curcumin have been demonstrated in various animal models of depression, however, there is little information regarding the site and mechanisms of curcumin in promoting antidepressant effects. The present study attempts to explore the mechanisms underlying the antidepressant-like action of curcumin by measuring the contents of brain derived neurotrophic factor (BDNF) in the amygdala of animal model of depression. The results showed that treatment with curcumin (40 mg/kg, i.p.) significantly reduced depressive-like behaviors of mice in the forced swim test. Chronic administration of curcumin (40 mg/kg, i.p., 21 days) increased BDNF protein levels in the amygdala and this enhancement was suppressed by pretreatment with the extracellular signal-regulated kinase (ERK) inhibitor SL327. Additionally, the increased levels of ERK phosphoryation in the amygdala by curcumin were blocked by the ERK inhibitor, and inhibition of this kinase prevented the antidepressant effects of curcumin. All of these effects of curcumin, were essentially identical to that observed with the clinical antidepressant, fluoxetine. These results suggest that the antidepressant-like effects of curcumin in the forced swim test are mediated, at least in part, by an ERK-regulated increase of BDNF expression in the amygdala of mice.

[The clinical and pathological changes following anterior-ethmoid neurotomy in treating perennial allergic rhinitis with plasma].

OBJECTIVE: To research the therapy effect of perennial allergic rhinitis (PAR) with anterior-ethmoid neurotomy, and to observe the pathological changes of SP nerve fibres. METHOD: In 46 cases (neurotomy group, NG) of PAR anterior-ethmoid neurotomy were performed, the surgery effect was evaluated according to the Chinese Hai Kou allergic rhinitis diagnosis and curative access standard (1997) and compared with 17 cases simulating operation without neurotomy (non-neurotomy group, NNG) by clinical symptoms controlled counting-scores. The substance P in nasal mucous membrane of NG was observed with immunohistochemical test, meanwhile the square of positive-stained nerve fibres on the sections were measured with a quantitative analysis method after and before operation, which also were compared with that of 14 cases patients without rhinopathy (normal controlled group, NCG). RESULT: The average score reduced from 12.93 pre-operation to 6.14 post-operation (P < 0.01) in NG, but in NNG there is no significant different before and after therapy. The squares of SP immune response (SP-IR) positive-stained fibers were significant different between pre-operation and post-operation in NG. The quantities of SP-IR positive-stained fibers in nasal mucous membrane were more in PAR patients (before operation) that that in the NCG. CONCLUSION: The anterior-ethmoid neurotomy with plasm technique is an effective and simple therapical method for treating PAR. The SP of anterior--ethmoid nerve plays an important role in the pathological mechanism of PAR.