A two-step sol-gel method for synthesis of nanoporous TiO2

This article reports a study of the effects of synthesis parameters on the preparation and formation of mesoporous titania nanopowders by employing a two-step sol-gel method. These materials displayed crystalline domains characteristic of anatase. The first step of the process involved the hydrolysis of titanium isopropoxide in a basic aqueous solution mediated by neutral surfactant. The solid product obtained from step 1 was then treated in an acidified ethanol solution containing the same titanium precursor to thicken the pore walls. Low pH and higher loading of the Ti precursor in step 2 produced better mesoporosity and crystallinity of titanium dioxide polymorphs. The resultant powder exhibited a high surface area (73.8 m2/g) and large pore volume (0.17 cm3/g) with uniform mesopores. These materials are envisaged to be used as precursors for mesoporous titania films as a wide band gap semiconductor in dye-sensitized nanocrystalline TiO2 solar cells.

Synthesis, characterization and optical properties of ordered macroporous organosilicasElectronic supplementary information (ESI) available: experimental details for materials preparation and characterizations, TGA curves and FTIR spectra. See http://www.rsc.org/suppdata/cc/b4/b403922j/

Ordered macroporous organosilica materials with uniform pore size in the range of 0.2-1.35 [micro sign]m have been fabricated by using self-assembled colloidal crystals as templates, and characterized with SEM, TGA, FTIR, MAS NMR, and optical reflectance spectrometry.

Mesoporous silica-immobilized aluminium chloride as a new catalyst system for the isopropylation of naphthalene

Mesoporous MCM-41 silica immobilized aluminium chloride shows high catalytic activity and selectivity in the Friedel-Crafts alkylation of naphthalene with isopropanol.

[Effect of dingxin recipe on intracellular free calcium, membrane potential and mitochondria membrane potential in normal and hypoxia myocytes of rats]

OBJECTIVE

To elucidate the molecular mechanism on anti-arrhythmic function of Dingxin Recipe (DXR).

METHODS

Cardial myocytes isolated by trypsin method were cultured and labelled with various fluorescence stains. DXR contained serum induced changes of cytolic calcium concentration [Ca2+]i, cell membrane potential (MP) and mitochondria membrane potential (MMP) were determined with laser confocal microscopy.

RESULTS

Hypoxia caused increase of [Ca2+]i and MMP, and decrease of MP, while DXR contained serum lowered the [Ca2+]i in normal or hypoxian myocytes, improved hypoxia induced MP reduction and maintain MMP at baseline level under hypoxia circumstances.

CONCLUSION

Through inhibiting the hypoxia caused [Ca2+]i and MMP elevation and MP lowering, DXR displays its action in protecting myocardial cells to prevent and treat arrhythmia.

Effect of cathepsin B on thymocyte apoptosis in spontaneously hypertensive rats

AIM

To further investigate the mechanism of the thymus dysfunction in spontaneously hypertensive rats.

METHODS

The location of cathepsin B expression was determined by in situ hybridization. The expression of cathepsin B was analyzed by Northern blot, and thymocyte apoptosis was detected by TUNEL and flow cytometer, respectively.

RESULTS

The expression of cathepsin B in thymus paralleled with thymocyte apoptosis both in vitro and in vivo. Cathepsin B transcripts were located in the plasma of thymocytes and were more over-expressed of 6- and 8-week-old SHR than those in the thymus of WKY.

CONCLUSION

Thymocyte apoptosis in SHR is increased and this phenomenon is associated with the expression of cathepsin B.

Fabrication and Characterization of a New Self-Assembled Monolayer of Fullerene Dicarboxylic Acid Derivative and Its Photoelectric Conversion Property

A new fullerene self-assembled monolayer (SAM) which has the property of photoelectric conversion is reported here. The SAM was fabricated on hydrophilic substrates by an esterification reaction. The SAM is characterized by contact angle, AFM, UV spectrum, and cyclic voltammetry. A cathodic photocurrent of 226 nA/cm(2) was obtained. Copyright 2000 Academic Press.

Identification of upregulated genes in the thymus of spontaneously hypertensive rats by cDNA representational difference analysis

OBJECTIVE

To investigate molecular events associated with thymus dysfunction in the spontaneously hypertensive rat (SHR), we analysed the difference in gene expression of the thymus between SHR and Wistar-Kyoto (WKY) rats.

METHODS

cDNA representational difference analysis (cDNA-RDA) was applied to compare the gene expression in the thymus between SHR and WKY. The difference products of cDNA-RDA were cloned into pBluescript SK (+) for differential screening. The positive clones were sequenced, and the sequences were analysed using the BLAST program for the homology search. Northern blot analysis was used to confirm the results of differential screening.

RESULTS

The results of differential screening showed that eight genes were over-expressed in the thymus of SHR. Comparison of eight sequences against the databases identified four known and four novel genes. The known genes included cathepsin B, AT1-46, cytochrome C oxidase subunit I and metastasis suppressor homolog (KAI1). Two of the novel genes are members of immunoglobulin superfamily genes, and the rest of the novel genes have no significant homology to non-redundant GenBank + EMBL + DDBJ + PDB. By Northern blot hybridization, cathepsin B and clone #7 (GenBank accession #AF106623) genes were confirmed to be overexpressed in the SHR thymus.

CONCLUSION

cDNA-RDA combined with differential screening can be used to detect easily the differentially regulated genes in two comparable tissues. The eight isolated genes are good clues toward understanding the development and function of SHR thymus.

Direct and indirect retinohypothalamic projections to the supraoptic nucleus in the female albino rat

Earlier studies have shown that retinohypothalamic projections terminate extensively within the hypothalamus of the rat. Recently, we identified a light retinal projection to the supraoptic nucleus as well as a larger, well-focused projection resulting in a peri-supraoptic nucleus terminal field. In this study, we employed a double labeling method with cholera toxin conjugated to horseradish peroxidase (CT-HRP) and pseudorabies virus, a transsynaptic neural tracer, to evaluate retinorecipient neurons in both the supraoptic nucleus and peri-supraoptic nucleus terminal field. In addition, we looked for evidence that cells in the peri-supraoptic nucleus terminal field project into the supraoptic nucleus. Three strains of pseudorabies virus were compared. A direct retinosupraoptic nucleus circuit was confirmed with all three strains. Retinorecipient neurons in the peri-supraoptic nucleus terminal field were also confirmed. However, there was a strain-based difference in the identification of these neurons. The wild-type Becker strain labeled cells in the peri-supraoptic nucleus terminal field in a manner paralleling the early, intermediate and late stages of infection of the suprachiasmatic nucleus. This parallel time course suggests that retinal ganglion cells terminate directly on cells in the peri-supraoptic nucleus terminal field. Conversely, the Bartha and PRV-91 strains showed appreciable labeling of peri-supraoptic neurons only at long survival times. This longer time course suggests that these mutant strains label neurons in the peri-supraoptic nucleus terminal field indirectly, after passing through additional neurons. In addition, experiments with monocular injection of CT-HRP and posterior pituitary injection of pseudorabies virus showed retrogradely labeled second-order cells in the peri-supraoptic nucleus amidst the CT-HRP labeled terminal field of the retinohypothalamic tract. These results demonstrate a direct projection from the retina to the supraoptic nucleus and provide evidence for an indirect circuit from the retina to the supraoptic nucleus via neurons located in the peri-supraoptic nucleus terminal field. The strain-based differences imply that those retinal ganglion cells that project to the peri-supraoptic nucleus terminal field differ from those that project to the suprachiasmatic nucleus. In addition, these results suggest a neuroanatomic basis for photic effects on physiological mechanisms that are not mediated by the circadian timing system.

[In vivo metastasis of human tumor transplant in T and NK cell immune-deficient mice]

Beige-nude mice with combined T and NK cell deficiency were produced by introducing "nu" gene into the beige mice of C57BL/6 background. The beige-nude mice were characterized by morphological features, level and activity of the NK cell in spleen and peripheral blood. NK cell level of the beige-nude mice was higher than the beige mice and similar to the ordinary nude mice though its NK cell activity was markedly lower than the nude mice. Human lung adenocarcinoma (PAa) was transplanted subcutaneously to the beige-nude mice and nude mice of BALB/cA background. No metastasis was found in BALB/cA nude mice (0/7), while in beige-nude mice, spontaneous lymph node metastasis rate was 36.3% (4/11). It should be noted that the transplanted PAa metastasized to lungs, which had never been seen in BALB/cA nude mice in previous experiments. The increase of metastatic rate is correlated with the relative low NK cell activity of the beige-nude mice. Our observation is that the beige-nude mice could be a suitable experimental model for in vivo study on metastatic behavior of the human tumors.