Effect of Temperature and Pressure of Supercritical CO2 on Dewatering, Shrinkage and Stresses of Eucalyptus Wood

Supercritical CO2 (SuCO2) dewatering can mitigate capillary tension and reduce wood collapse. In this study, Eucalyptus urophylla × E. grandis specimens were dewatered by SuCO2 at temperatures of 35, 40 and 55 °C, in pressures of 10 and 30 MPa, respectively, for 1h. Effects of temperature and pressure on dewatering rate, moisture content (MC) distribution and gradient, shrinkage and residual stress of wood after dewatering were investigated. The results indicate that the SuCO2 dewatering rate is much faster than that of conventional kiln drying (CKD). The dewatering rate increases with increasing of temperature and pressure; however, pressure has a significant influence, especially for the high-temperature dewatering process; the MC distribution after 1 h dewatering is uneven and MC gradients decrease with reducing of mean final MC of wood. MC gradients along radial direction are much smaller than that in tangential direction; collapse of wood significantly reduces after dewatering due to SuCO2 decreasing the capillary tension, and residual stress of wood during dewatering is mainly caused by pressure of SuCO2, which decreases with increasing temperature. SuCO2 dewatering has great potential advantages in water-removal of wood prone to collapse or deformation.

Groundwater Level

Groundwater level has long been known to respond to earthquakes; several types of response have been documented. Advances in the last decade were made largely through the studies of water-level response to Earth tides and barometric pressure. These studies have demonstrated that the hydraulic properties of groundwater systems are dynamic and change with time in response to disturbances such as earthquakes. This approach has been applied to estimate the permeability of several drilled active fault zones, to identify leakage from deep aquifers used for the storage of hazardous wastewater, and to reveal the potential importance of soil water and capillary tension in the unsaturated zone. Enhanced permeability is the most cited mechanism for the sustained changes of groundwater level in the intermediate and far fields, while undrained consolidation remains the most cited mechanism for the step-like coseismic changes in the near field. A new mechanism has emerged that suggests that coseismic release of pore water from unsaturated soils may also cause step-like increases of water level. Laboratory experiments show that both the undrained consolidation and the release of water from unsaturated zone may occur to explain the step-like water-level changes in the near field.

Drying Characteristics of Eucalyptus urophylla × E. grandis with Supercritical CO2

Supercritical CO2 (ScCO2) is a drying medium with excellent solubility and mass transfer efficiency. Supercritical CO2 drying (SCD) can remove the water of wood rapidly and prevent a change of microstructure caused by capillary tension in the drying process. In this study, Eucalyptus urophylla × E. grandis specimens with lengths of 50 and 100 mm were dried with ScCO2. Conventional kiln drying (CKD) and oven-drying (OD) were used as control. After 1 h, the drying rate, shrinkage, moisture distribution, drying stress were measured to explore the influence of drying methods and specimen length for drying characteristics during the early drying stage. The results showed that compared with CKD and OD, water removal was the fastest under SCD, and the drying rate was nine times of CKD and one time of OD. The shrinkage of SCD was the lowest among the three drying methods. Moisture distribution of SCD and OD was uneven. The drying stress of SCD was relatively high, the drying stress index of it was almost five times of CKD and three times of OD. Regardless of the drying method, shorter specimens had a shorter drying period but greater drying defects than the long specimens.

Effect of CaSO4 Incorporation on Pore Structure and Drying Shrinkage of Alkali-Activated Binders

This present study investigates the effects of CaSO4 incorporation on the pore structure and drying shrinkage of alkali-activated slag and fly ash. The slag and fly ash were activated at a 5:5 ratio by weighing with a sodium silicate. Thereafter, 0%, 5%, 10%, and 15% of CaSO4 were incorporated to investigate the changes in phase formation and internal pore structure. X-Ray Diffraction (XRD), thermogravimetry (TG)/derivative thermogravimetry (DTG), mercury intrusion porosimetry (MIP), nuclear magnetic resonance (NMR), and drying shrinkage tests were carried out to find the correlation between the pore structure and drying shrinkage of the specimens. The results showed that CaSO4 incorporation increased the formation of thenardite, and these phase changes affected the pore structure of the activated fly ash and slag. The increase in the CaSO4 content increased the pore distribution in the mesopore. As a result, the capillary tension and drying shrinkage decreased.

Aspiration and non-aspiration technique in the study of thyroid gland lesion cytology

Background: Fine needle aspiration cytology is used as a primary diagnostic tool in thyroid lesions. But the bloody smears caused by negative pressure during aspiration compromise cellular concentration and cell morphology which may lead to its improper interpretation. FNNAC avoids active aspiration and depends on capillary tension to collect tissue sample in the needle bore, thus reducing bleeding and tissue trauma to the highly vascular thyroid. Material and Methods: This is a one year prospective study where FNNAC and FNAC were done on 87 patients. Cytopathologist was blind folded regarding the technique used and was asked to score the quality of slide base of Mair scoring system.Results: FNAC yielded significantly better material on the basis of hemorrhage and cellularity. Fifty six (64.37%) cases showed adequate diagnostic material in FNNAC technique while 54/87 (62.05%) cases showed adequate diagnostic material in FNAC technique. Twelve (13.79%) cases showed unsuitable diagnostic material in FNNAC technique and 26/ 87 (29.89%) cases unsuitable diagnostic material in FNAC technique. Among the individual criteria used in Mair scoring system, background clot/ blood was significantly low in FNNAC than FNAC with the p value less than 0.001. Amount of cellular material was significantly more in FNNAC with p value less than 0.001.Conclusion: FNNAC yielded more cellular and less hemorrhagic material and more diagnostic superior material than FNAC. Since thyroid is a highly vascular gland, FNNAC should be used instead of FNAC for less hemorrhagic and more cellular material.

Manufacture of the Glass Nanopore Based on Laser Heating and Experimental Research

The glass nanopore produced by the physical method has better physical characteristics, higher strength, stronger stability, longer life and other significant features compared with the chemical method. The purpose of this paper is to study DNA sequencing (973 project) to provide experimental basis for preparation of glass capillary 5nm 3D nanochannel In this paper, we design a set of glass capillary tension system which is controlled by laser heating and linear ultrasonic motor and produced successfully the device for the preparation of nanopore below 50 nm. In addition, the use of micro droplet generation system has carried out preliminary characterization of nanopore drawn devices. Seen from the characterization, the nanopore device fabricated can indeed produce a through-hole.

Nanopore in C-S-H Gel Stability Analysis of Hardened Cement Pastes

Based on capillary tension, surface free energy and elasticity theory, a collapse model of nanopore in C-S-H gel was created in hardened cement pastes. The stability of pore was analyzed by Gibbs free energy theory. The results show that, the capillary is more stable while the capillary is grater and rounder in the case of the aperture changing in the nanometer scope. When the aperture is changing in the scope of micrometer, the collapse possibility of the capillary is tiny. If the capillary size is fixed, the capillary is more stable while the elastic modulus of hydrated products is higher.