Effects of surfactant/silica and silica/cerium ratios on the characteristics of mesoporous Ce-MCM-41

Using the surfactant CTMABr (cetyltrimethyl ammonium bromide) and cerium(IV) sulfate, mesoporous Ce-MCM-41 molecular sieves were produced under a hydrothermal condition with various surfactant/silica (surfactant/Si) and silica/cerium (Si/Ce) ratios. Changes to the structural traits caused by changing the molar ratios of both surfactant/Si and Si/Ce were investigated. XRD (X-ray diffraction), FT-IR (fourier transform infrared spectroscopy), and SEM (scanning electro microscopy) were used for the characterization of prepared mesoporous samples. Among the tested molar ratios, surfactant/Si ratio of 0.5 and 0.2 showed highest values of d_1 0 0 and intensity, respectively, for the Si-MCM-41. XRD analysis also identified a quintessential hexagonal structure of Ce-MCM-41 for the Si/Ce molar ratio higher than 40 (maintaining the surfactant/Si ratio at 0.2). When cerium content was increased to have the Si/Ce molar ratio of 20, the hexagonal structure of Ce-MCM-41 was collapsed due to the structural stress of substituted cerium. FT-IR results confirmed calcination of Ce-MCM-41 and the incorporation of Ce⁴⁺ ions of cerium sulfate into the silica surface with proper removal of the surfactant. Rod-like shape with rounded edges of the prepared Ce-MCM-41 samples was identified by SEM. These results suggest surfactant/Si ratio of 0.2 and Si/Ce ratio of 40 for the production of Ce-MCM-41 with the highest level of crystallinity.     

Gastrointestinal autonomic nerve tumour presenting as small bowel volvulus: a rare disease with a rare presentation

A 78-year-old Chinese woman presented with recurrent postprandial abdominal pain. Computerised tomography revealed a small bowel tumour causing volvulus of a segment of the small bowel. Laparotomy confirmed an extraluminal ileal tumour with partial volvulus of the involved small bowel segment. Small bowel resection was done. Histological and ultrastructural studies confirmed a gastrointestinal autonomic nerve tumour. We review the medical literature on this rare tumour.     

Designing better adaptive sampling algorithms for ECG Holtersystems

Let Ψ be any adaptive sampling algorithm that can run in real time on a tapeless multichannel electrocardiogram (ECG) Holter system. Simple methods which can significantly improve Ψ's fidelity are described and their results are compared in this paper. It is shown that by adding some simple tests to Ψ, the signals reconstructed by Ψ can be improved as much as 5.45 dB. It is also shown that under the same data rate, a good data compressor with slowly sampled input ECG is preferable to a bad data compressor with highly sampled input ECG     

L~∞（0，1）上一个WeakL~P（0，1）有关的格半范数

本文引进一个定义在Ｌ~∞（０，１）上格半范数ρｐ与一个熟知的格半范数ρ０关系，证明了在Ｌ~∞（０，１）中的序区间上，ρ０－拓扑与ρｐ－拓扑等价，从而证明了（Ｌ~∞（０，１），ρｐ）′的闭单位球是（Ｌ~∞（０，１），ρｐ）′的某个子集的弱－闭包，本文还证明了（Ｌ~∞（０，１），ρｐ）′可看作ＷｅａｋＬｐ（０，１）对偶空间的奇异部一个理想，而且这奇异部可由（Ｌ~∞（０，１），ρｐ）′与一算子族生成．（ｆ）ａｌｌ（ｌ．＼ｎ，ｏｏ（ｊ．）＝ｈｉｌｌｓｉｌｌ）ｔ￣．，ｉｆｆ￣＊（ｔ）ｒｅｓｐｅｃｔｉｖｅｌｙａｌｌ＇ｌ，Ｌ（ｑ，１）ｉｓｔｈｅｐｒｅｄｌｓｌａｌｏｆｔｙｒｅａｋＬＩ＇，ａｌｌｌｌｈ，ｒｌｌｏｌｌ－－ａｔ（，ｌｌｌｉ（＇ｌｌｌｅａｓｌｌｒｅａｌｇａ（ｌ￣ｓ，ａｒｅｐｒｅｓｅｌｌｔａ＇ｔｉｏｌｌｔｌｌｅｏｒｅｎｌｆｆ，ｒｅｌｅｌｌｌｅｌｌｔｓｉｌｌＳａｃ，ａｌｌ（ｌＳ，，．ｉｓｏｆ）ｔａｉｌｌｅ（ｌ．Ｈｏｗｅｖｅｒ，ｉｌｌ［２］，ｉｔｉｓｓｌｌｄｗｎｔｈａｔｔｉｌｅｒｅｐｒｅｓｅｌｌｔａｔｉｏｌｌｔｉｌｅｓｆ）ｒｅｌｌｌｏｆ）ｔａｉｌｌｅ（ｌｉｌｌ［．５］ｉｓｉｌｌ（ｔｏｒｒｅ（？ｔ．Ｉｎｔｈｉｓｎｏｔｅ，ｗｅｄｅ     

Study of Desorption and Adsorption During Grain Aeration

One requirement in designing and operating and operating system is to minimize the moisture change in stored grain. Moisture transfer during the aeration process is generally believed to be caused by the partial pressure difference between water in grain and water in air (P₃-P₄). A mathematical model was developed for rough rice, which predicts the partial pressure difference under various grain and ambient conditions. Observations of moisture change over 10 aeration tests confirmed the good correlation between sorption phenomena and partial pressure differences. Studies indicated that air relative humidity, air temperature, grain temperature and grain moisture are significant factors influencing the partial pressure differences and, thus, affecting     

Preliminary studies using hybrid mediated electrochemical oxidation (HMEO) for the removal of persistent organic pollutants (POPs).

This study investigates the hybrid mediated electrochemical oxidation (HMEO) technology, which is a newly developed non thermal electrochemical oxidation process for organic destruction. A combination of ozone and ultrasonication processes to the mediated electrochemical oxidation (MEO) process is termed as hybrid mediated electrochemical oxidation. The electrochemical cell was developed in this laboratory. In the present study, several organic compounds, such as phenol, benzoquinone and ethylenediaminetetraacetic acid (EDTA), were chosen as the model organic pollutants to be destructed by the hybrid process. The organic destruction was monitored based on the CO2 generation and total organic carbon (TOC) reduction. The HMEO process was found to be extremely effective in the destruction of all the target organics chosen in this study. The information obtained from this study will provide an insight in adopting this technique for dealing with more recalcitrant organics (POPs).     

On the behavior of microstructures with multiple length scales

The current study aims to provide fundamental insight into the behavior of microstructures containing grain sizes that span multiple length scales. A commercial 5083 Al alloy was selected as the material of interest to facilitate comparison with recently published data. The materials studied here were prepared via the thermal consolidation of powders that were cryomilled for different times (i.e., 0, 2, 4, and 8 hours). Following consolidation, the resultant microstructure was characterized by an equiaxed grain morphology with a size distribution centered around 200∼300 nm. Dispersed among the 200- to 300-nm grains were coarse-grained regions or ligaments with a grain size ranging from 600 nm to 2 μm. The occurrence of coarse-grained regions is rationalized on the basis of recrystallization or subgrain coarsening, whereas the occurrence of equiaxed fine regions is proposed to be a result of continuous grain growth. Two types of microstructures were selected for study, containing coarse-grained volumes of approximately 28 pct and 43 pct that corresponded to an ultimate tensile strength (UTS) of 566 MPa and 535 MPa, and a fracture strain of 3.2 pct and 3.5 pct, respectively. The observed ductility and the relevant toughening mechanisms were discussed in light of the presence of multiple length scales.     

Effects of reducing and oxidizing atmospheres on the PTCR characteristics of porous n-BaTiO3 ceramics by adding polyethylene glycol

Donor doped BaTiO₃ (n-BaTiO₃) ceramics were fabricated by adding polyethylene glycol (PEG) at 20 wt %. The effects of reducing and oxidizing atmospheres on the PTCR characteristics of the porous n-BaTiO₃ ceramics were investigated. The PTCR characteristics of the porous n-BaTiO₃ ceramics is strongly affected by chemisorbed oxygen at the grain boundaries and are recovered as the atmosphere is changed from the reducing gas to oxidizing gas. The low room-temperature resistivity of the porous n-BaTiO₃ ceramics in reducing atmospheres may be caused by the decrease in potential barrier height, which originates from an increase in the number of electrons owing to the desorption of chemisorbed oxygen atoms at the grain boundaries. In addition, the high room-temperature resistivity of the porous n-BaTiO₃ ceramics in oxidizing atmospheres may be caused by the increase in potential barrier height, which results from the adsorption of chemisorbed oxygen atoms at the grain boundaries.