A study on the mechanism of the abnormal reduction of Eu3+ -> Eu2+ in Sr2B5O9Cl prepared in air at high temperature

This paper reports a new observation of the abnormal reduction of Eu3+ --> Eu2+ in Sr2B5O9Cl when prepared in air at high temperature. A model based on the nature of substitution defects is proposed to explain this abnormal reduction. Electrons, which reduced the Eu3+ ions, are created by the substitution of cations first and then transferred to the target Eu3+ ions via tetrahedral berate anion groups. Codoping experiments are designed and performed. The results of these experiments support the model proposed. (C) 1999 Academic Press.

Abnormal IR spectra of CO adsorbed on the surface of glass carbon electrode modified with polypyrrole film with platinum microparticles

Abnormal IR spectra of CO adsorbed at the surface of glass carbon electrode modified with polypyrrole film with Pt microparticles are reported.

华南震旦纪-寒武纪两期成磷事件及其地球动力学意义

Phosphorus is an important biological and ecological element that to a certain degree constrains ecological environment and nutrient (including carbon) cycling. Marine sedimentary phosphorites are the principal phosphorus supply of the mankind. In the eastern to southern margins of the Yangtze Craton, South China, there are two phosphogenetic events at the Doushantuo stage of the Late Sinian and the Meishucun stage of the Early Cambrian respectively, corresponding two explosion events of life across the Precambrian\Cambrian boundary. Phosphorus ores from the Sinian and Cambrian phosphate in South China can be classified roughly into two categories, namely, grained and non-grained phosphorites. Grained phosphorites, hosted in dolostone type of phosphogenetic sequences and with larger industrial values, occur mainly in margins of the Upper Yangtze Platform, formed in shallow-water environments with high hydraulic energy and influenced by frequent sea-level change. Non-grained phosphorites, hosted principally in black-shale type of phosphogenetic sequences and with smaller industrial values, are distributed mainly in the Jiangnan region where deeper-water sub-basins with low hydraulic energy were prevailing at the time of phosphogenesis. Secular change ofδ~(13)C, δ~(18) O, ~(86)Sr/~(87)Sr values of carbonates from Sinian and Cambrian sequences were determined. A negative abnormal ofδ~(13)C, δ~(18)O values and positive abnormal of 86Sr/87Sr values from the fossiliferous section of the Lowest Cambrian Meishucun Formation implies life depopulation and following explosion of life across the PrecambriamCambrian boundary. Based on a lot of observations, this paper put forward a six-stage genetic model describing the whole formational process of industrial phosphorites: 1) Phosphorus was transported from continental weathering products and stored in the ocean; 2) dissolved phosphates in the seawater were enriched in specific deep seawater layer; 3) coastal upwelling currents took this phosphorus-rich seawater to a specific coastal area where phosphorus was captured by oceanic microbes; 4) clastic sediments in this upwelling area were enriched in phosphorus because of abundant phosphorus-rich organic matters and because of phosphorus absorption on grain surfaces; 5) during early diagenesis, the phosphorus enriched in the clastic sediments was released into interstitial water by decomposition and desorption, and then transported to the oxidation-reduction interface where authigenic phosphates were deposited and enriched; 6) such authigenic phosphate-rich layers were scoured, broken up, and winnowed in shallow-water environments resulting in phosphate enrichment. The Sinian-Cambrian phosphorites in South China are in many aspects comparable with coastal-upwelling phosphorites of younger geological ages, especially with phosphorites from modern coastal upwelling areas. That implies the similarities between the Sinian-Cambrian ocean and the modern ocean. Although Sinian-Cambrian oceanic life was much simpler than modern one, but similar oceanic planktons prevail, because oceanic planktons (particularly phytoplanktons) are crucial for phosphate enrichment related to coastal upwelling. It implies also a similar seawater-layering pattern between the Sinian-Cambrian ocean and the modern ocean. The two global phosphate-forming events and corresponding life-explosion events at the Sinian and Cambrian time probably resulted from dissolved-phosphate accumulation in seawater over a critical concentration during the Earth's evolution. Such an oceanic system with seawater phosphorus supersaturation is evidently unstable, and trends to return to normal state through phosphate deposition. Accordingly, this paper put forward a new conception of "normal state <=> phosphorus-supersaturation state" cycling of oceanic system. Such "normal state <=> phosphorus-supersaturation state" cycling was not only important for the three well-known global phosphate-forming events, also related to the critical moments of life evolution on the Earth. It might be of special significance. The favorable paleo-oceanic orientation in regard to coastal-upwelling phosphorite formation suggests a different orientation of the Yangtze Craton between the Sinian time and the present time (with a 135° clockwise difference), and a 25° anti-clockwise rotation of the Yangtze Craton from late Sinian to early Cambrian. During the Sinian-Cambrian time, the Yangtze Craton might be separated from the Cathaysia Block, but might be still associated with the North China Craton.

Economic return of clinical trials performed under the pediatric exclusivity program.

CONTEXT: In 1997, Congress authorized the US Food and Drug Administration (FDA) to grant 6-month extensions of marketing rights through the Pediatric Exclusivity Program if industry sponsors complete FDA-requested pediatric trials. The program has been praised for creating incentives for studies in children and has been criticized as a "windfall" to the innovator drug industry. This critique has been a substantial part of congressional debate on the program, which is due to expire in 2007. OBJECTIVE: To quantify the economic return to industry for completing pediatric exclusivity trials. DESIGN AND SETTING: A cohort study of programs conducted for pediatric exclusivity. Nine drugs that were granted pediatric exclusivity were selected. From the final study reports submitted to the FDA (2002-2004), key elements of the clinical trial design and study operations were obtained, and the cost of performing each study was estimated and converted into estimates of after-tax cash outflows. Three-year market sales were obtained and converted into estimates of after-tax cash inflows based on 6 months of additional market protection. Net economic return (cash inflows minus outflows) and net return-to-costs ratio (net economic return divided by cash outflows) for each product were then calculated. MAIN OUTCOME MEASURES: Net economic return and net return-to-cost ratio. RESULTS: The indications studied reflect a broad representation of the program: asthma, tumors, attention-deficit/hyperactivity disorder, hypertension, depression/generalized anxiety disorder, diabetes mellitus, gastroesophageal reflux, bacterial infection, and bone mineralization. The distribution of net economic return for 6 months of exclusivity varied substantially among products (net economic return ranged from -$8.9 million to $507.9 million and net return-to-cost ratio ranged from -0.68 to 73.63). CONCLUSIONS: The economic return for pediatric exclusivity is variable. As an incentive to complete much-needed clinical trials in children, pediatric exclusivity can generate lucrative returns or produce more modest returns on investment.

Return to sport after open and microdiscectomy surgery versus conservative treatment for lumbar disc herniation: a systematic review with meta-analysis.

BACKGROUND: Lumbar disc herniation has a prevalence of up to 58% in the athletic population. Lumbar discectomy is a common surgical procedure to alleviate pain and disability in athletes. We systematically reviewed the current clinical evidence regarding athlete return to sport (RTS) following lumbar discectomy compared to conservative treatment. METHODS: A computer-assisted literature search of MEDLINE, CINAHL, Web of Science, PEDro, OVID and PubMed databases (from inception to August 2015) was utilised using keywords related to lumbar disc herniation and surgery. The design of this systematic review was developed using the guidelines of the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA). Methodological quality of individual studies was assessed using the Downs and Black scale (0-16 points). RESULTS: The search strategy revealed 14 articles. Downs and Black quality scores were generally low with no articles in this review earning a high-quality rating, only 5 articles earning a moderate quality rating and 9 of the 14 articles earning a low-quality rating. The pooled RTS for surgical intervention of all included studies was 81% (95% CI 76% to 86%) with significant heterogeneity (I(2)=63.4%, p<0.001) although pooled estimates report only 59% RTS at same level. Pooled analysis showed no difference in RTS rate between surgical (84% (95% CI 77% to 90%)) and conservative intervention (76% (95% CI 56% to 92%); p=0.33). CONCLUSIONS: Studies comparing surgical versus conservative treatment found no significant difference between groups regarding RTS. Not all athletes that RTS return at the level of participation they performed at prior to surgery. Owing to the heterogeneity and low methodological quality of included studies, rates of RTS cannot be accurately determined.

Return of deposits

Explores case law illustrating the circumstances in which the courts are likely to order the return of a deposit in the event of a buyer's default. Notes the unwillingness of the courts to apply the rule on penalties to deposits and discusses the court's discretion under the Law of Property Act 1925 s.49(2) to order repayment. Focuses on the Chancery Division ruling in Aribisala v St James Homes (Grosvenor Dock) Ltd giving guidance on the circumstances in which the discretion under s.49(2) should be exercised.