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In the hydrothermal crystallization of zeolites from basic media, hydroxide ions (OH(-)) catalyze the depolymerization of the aluminosilicate gel by breaking the Si,Al-O-Si,Al bonds and catalyze the polymerization of the aluminosilicate anions around the hydrated cation species by remaking the Si,Al-O-Si,Al bonds. We report that hydroxyl free radicals (•OH) are involved in the zeolite crystallization under hydrothermal conditions. The crystallization processes of zeolites-such as Na-A, Na-X, NaZ-21, and silicalite-1-can be accelerated with hydroxyl free radicals generated by ultraviolet irradiation or Fenton's reagent.

The variations of summer and winter monsoons during the Holocene in the eastern Tibetan Plateau are shown to follow two basic models based on the reliable dating and high-resolution monsoon proxies determinations, one being a synchronous model in that both summer and winter monsoons are strengthening or decreasing, and the other to form a complementary pattern. These two different patterns evenly interact with each other on different time scales and together compose a complicated monsoon climatic model in this region. The climatic condition integrated by winter and summer monsoons is synchronous to the global pattern, which also shows the instability of the Holocene climate on centennial-millennial timescale. The abrupt monsoon event in about 6.2 ka cal. BP is much more severe than that in ca. 8.0 ka cal. BP, which indicates the regional character of the Asian monsoon and that the Asian monsoon climate is indeed a window on the global climate system.

Radiocarbon accelerator mass spectrometry (AMS) techniques were used to date total organic carbon and plant seeds in the 1Fs core sequence (36°48′N, 100°08′E) from Qinghai Lake, China. This core was drilled ~18 m into Qinghai Lake sediments as part of an international cooperative research project, "Scientific Drilling at Qinghai Lake in the Northeastern Tibetan Plateau: High-Resolution Paleoenvironmental Records of Eastern Asia Linked to Global Change," which began in 2004. Based on the differences in lithology and total organic content (TOC) in core 1Fs, the core was divided into 3 sections for age-modeling purposes: the upper ~499 cm lacustrine silty clay to clay; the middle unit of silty clay with silt layers from 499-901 cm; and the lower 901-1861 cm silty clay, loess-like silt, and fine sand layers. Three different approaches are applied to the reservoir age problem. First, a simple linear regression gives an offset of 1342 yr. If the core is divided into three sections, linear regressions can be applied separately for the three segments, which results in an age estimate for the average hardwater effect of ~135 yr BP for the surface section up to 499 cm. If extrapolated for deeper sections, these results imply a higher reservoir offset for those two sections, which may be as much as 1143 and 2523 yr, but this assumes that there are no discontinuities in the core. A third approach using a wiggle-matching approach gave an offset of 196 yr. This study concludes that the reservoir age of Qinghai Lake is complex, but these new data add to our understanding of the 14 C chronology of Qinghai Lake for the last 32 ka.

A series of single-cell, hydrogen-air proton exchange membrane fuel cells ͑PEMFCs͒ was operated for different lengths of time, namely, 200, 500, 700, and 1000 h. A group of reproducible and identical membrane electrode assemblies ͑MEAs͒ was used for those tests. Cell performance was studied by examining the cell polarization curves. After various lifetime tests, each MEA was cross-cut and characterized by X-ray diffraction ͑XRD͒, transmission electron microscopy ͑TEM͒, scanning electron microscopy, and Raman techniques to investigate any changes in catalyst structure and morphology, as well as particle size and chemical composition. The average particle size of the catalysts was calculated from XRD results and was found to increase with cell operating time. In addition, the agglomeration in nanometer-sized catalyst particles was observed from TEM analysis after prolonged cell operation. Ruthenium oxide was identified from Raman spectra of the anode catalyst from the tested MEAs, while no oxides were found on the cathode catalyst at the cell operating voltage. It is possible that the formation of metal oxides at the surface of the anode catalyst led to larger particles and ultimately resulted in the decrease of catalyst activity. This might be responsible for the slightly degraded cell performance following 700 h of operation.

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