Publications

Objective To observe the dose effect of nicardipine used for depressing blood pressure during operation.Methods Fifty patients of selective surgery under general anesthesia were divided into 5 groups including 10 patients respectively at random.When systolic blood pressure(SBP)≥160 mmHg and/or diastolic blood pressure(DBP)≥95 mmHg in operation,nicardipine was infused.The changes of SBP,DBP and HR at different stages were observed and recorded before and after nicardipine was given.Results The SBP?DBP decreased obviously in all groups after nicardipine infused intravenously.But the time of blood pressure decreasing to normal value was different.The time is 6 min in group Ⅰ, 4 min in group Ⅱ, 2 min in group Ⅲ,2 min in group Ⅳ,1 min in group Ⅴ respectively.There was no difference in HR before and after nicardipine infused intravenously.Conclusion The time that nicardipine starts to show effect is related to the doses.

Ultra high performance concrete (UHPC) has become one of promising concretes in the last decade because of its excellent performance, such as high strength, low permeability and very good durability. However, like high performance concrete, UHPC is also subjected to high autogenous shrinkage due to high amount of cement and silica fume used. Seeking the ways to reduce the autogenous shrinkage is a very important task in the field of cement and concrete research. In this paper, the Rice husk ash, an agriculture waste, is explored to mitigate the autogenous shrinkage of UHPC. With high amorphous SiO2 content and special porous structure, the RHA shows not only reduce the cost and improve the early age properties of the UHPC but also increase the environmental benefits.

After placing repair material on concrete substrate,the moisture exchange takes place between the repair material and the concrete substrate,driven by the capillary pressure gradient.The resultant change of water content in the repair material affects the cement hydration process,the microstructure development and thus the bond strength.In this paper,the influence of moisture exchange on the degree of hydration and porosity of the repair material and on the bond strength between two materials was investigated.The experimental results show that the saturated concrete substrate can provide the additional water for the hydration of the repair material and lead to a higher degree of hydration.When placing a repair material on an unsaturated concrete substrate,the unsaturated concrete substrate can absorbs a large amount of water from the repair material.The water loss in the repair material results in a de-crease in water cement ratio.Consequently,the repair material cast on the unsaturated substrate shows a lower degree of hydration and a lower porosity compared to those cast on the saturated substrate.Also the decrease of water cement ratio leads to a high bond strength between the repair material and the concrete substrate.

A high-performance liquid chromatography method with solid-phase extraction is introduced for the determination of geniposide in rat urine after oral administration of Yin-Zhi-Ku decoction. Geniposide and an internal standard (paeoniflorin) are extracted from urine using Strata cartridges. Analysis of the extract is then performed on a reversed-phase C18 column using acetonitrile water (14:86, v/v) as eluting solvent system. UV detection is set at 238 nm. The calibration curve for geniposide is linear (r = 0.9996) in the concentration range of 2.0–240 µg/mL. Both intra- and interday precision of the geniposide are determined, and their relative standard deviation does not exceed 10%. The validated method is successfully applied to determine geniposide from rat urine after oral administration of Yin-Zhi-Ku decoction.

A complete understanding of the mechanisms upon which a filler acts in a cement-based material, e.g. as a C–S–H nucleation and/or growth-inducing factor, is of high importance. Although various studies report on accelerated cement hydration in the presence of fillers, the reason behind these observations is not completely understood yet. This work contributes to this subject, by providing an experimental evidence on the (electro) chemical aspects of the filler surface modification in the model solution, simulating the pore solution of cement paste. The nature of the various interactions with regard to the affinity of a filler surface towards C–S–H nucleation and growth was discussed in detail in this work with regard to zeta potential measurements of micronized sand and limestone particles in the model solutions. These results are further supported by microscopic observations of morphology and distribution of hydration products on the filler surfaces, together with considerations on thermodynamic principles in view of hydration products formation and distribution. The C–S–H nucleation and growth appeared to be due to the interactions between a filler surface and calcium ions in the pore solution. These interactions were determined by the chemical nature of the filler surface. The interaction mechanisms were found to be governed by relatively weak electrostatic forces in the case of micronized sand. This was reflected by a non-significant adsorption of calcium ions on the filler surface, resulting in non-uniformly distributed and less stable C–S–H nuclei. In contrast, the nucleation and growth of C–S–H on limestone particles were predominantly determined by donor–acceptor mechanisms, following moderate acid–base interactions. Consequently, a strong chemical bonding of calcium ions to a limestone surface resulted in a large amount of uniformly distributed C–S–H nuclei.

The sustainability of infrastructure projects is becoming increasingly important issue in engineering practice. This means that in the future the construction materials will be selected on the basis of the contribution they can make to reach sustainability requirements. Geopolymers are materials based on by-products from industries. By using geopolymer concrete technology it is possible to reduce our waste and to produce concrete in the environmental-friendly way. An 80% or greater reduction of greenhouse gases compared with Ordinary Portland Cement (OPC) can be achieved through geopolymer technology. However, there are limited practical applications and experience. For a broad and large scale industrial application of geopolymer concrete, challenges still exist in the technological and engineering aspects. The main goal of GeoCon Bridge project was to develop a geopolymer concrete mixture and to upscale it to structural application. The outputs of projects provide input for development of recommendations for structural design of geopolymer based reinforced concrete elements. Through a combination of laboratory experiments on material and structural elements, structural design and finite element simulations, and based on previous experience with OPC concrete, knowledge generated in this project provides an important step towards a “cement free” construction. The project was performed jointly by three team members: Microlab and Group of Concrete Structures from Technical University of Delft and Technical University of Eindhoven.