Assays that measure steroid hormones in patient care, public health, and research need to be both accurate and precise, as these criteria help to ensure comparability across all clinical and research applications. Thi...Assays that measure steroid hormones in patient care, public health, and research need to be both accurate and precise, as these criteria help to ensure comparability across all clinical and research applications. This review addresses major issues relevant to assay variability and describes recent activities by the US Centers for Disease Control and Prevention （CDC） to improve assay performance. Currently, high degrees of accuracy and precision are not always met for testosterone and estradiol measurements; although technologies for steroid hormone measurement have advanced significantly, measurement variability within and across laboratories has not improved accordingly. Differences in calibration and specificity are discussed as sources of variability in measurement accuracy. Ultimately, a combination of factors appears to cause inaccuracy of steroid hormone measurements, with nonuniform assay calibration and lack of specificity being two major contributors to assay variability. Within-assay variability for current assays is generally high, especially at low analyte concentrations. The CDC Hormone Standardization （HoSt） Program is improving clinical assays, as evidenced by a 50% decline in mean absolute bias between mass spectrometry assays and the CDC reference method from 2007 to 2011. This program provides the measurement traceability to CDC reference methods and helps to minimize factors affecting measurement variability.展开更多
For much of the world＇s population, food is the major source of exposure to arsenic.Exposure to this non-essential metalloid at relatively low levels may be linked to a wide range of adverse health effects. Thus, eva...For much of the world＇s population, food is the major source of exposure to arsenic.Exposure to this non-essential metalloid at relatively low levels may be linked to a wide range of adverse health effects. Thus, evaluating foods as sources of exposure to arsenic is important in assessing risk and developing strategies that protect public health. Although most emphasis has been placed on inorganic arsenic as human carcinogen and toxicant, an array of arsenic-containing species are found in plants and animals used as foods. Here,we 2evaluate the contribution of complex organic arsenicals（arsenosugars, arsenolipids,and trimethylarsonium compounds） that are found in foods and consider their origins,metabolism, and potential toxicity. Commonalities in the metabolism of arsenosugars and arsenolipids lead to the production of di-methylated arsenicals which are known to exert many toxic effects. Evaluating foods as sources of exposure to these complex organic arsenicals and understanding the formation of reactive metabolites may be critical in assessing their contribution to aggregate exposure to arsenic.展开更多
A catalytic multi-component reaction involving aromatic amine,aromatic aldehydes,mercapto acid as substrates and Bi（SCH_2COOH）_3 as catalyst under solvent free conditions,afforded thiazolidin-4-one in good yields.Th...A catalytic multi-component reaction involving aromatic amine,aromatic aldehydes,mercapto acid as substrates and Bi（SCH_2COOH）_3 as catalyst under solvent free conditions,afforded thiazolidin-4-one in good yields.The efficiency of the catalyst was proved with a variety of substrates,ranging from electrondeficient to electron-rich aldehydes.展开更多
To understand the influence of the diagenetic water medium on the isotopic compositions of thermogenic coalbed gas,both hydrous and anhydrous closed-system pyrolyses were performed at temperatures of 250°C to 650...To understand the influence of the diagenetic water medium on the isotopic compositions of thermogenic coalbed gas,both hydrous and anhydrous closed-system pyrolyses were performed at temperatures of 250°C to 650°C on an herbaceous marsh peat.Compared to the results of anhydrous pyrolysis,the hydrocarbon gases generated from hydrous pyrolyses have very different hydrogen isotopic compositions.However,the carbon isotopic compositions of the hydrocarbon gases became only slightly heavier in hydrous pyrolysis,compared to that from anhydrous pyrolysis.With the progress of thermal evolution from peat to a more advanced thermal maturity of vitrinite reflectance values(Ro)of 5.5%during the pyrolysis,the difference in the averageδD value increased from 52‰to 64‰between the hydrous pyrolysis with saltwater and anhydrous pyrolysis and increased from 18‰to 29‰between the hydrous pyrolysis with freshwater and anhydrous pyrolysis,respectively.The difference in the averageδ^(13)C value was only 1‰–2‰between the hydrous and anhydrous pyrolysis.The relationships between theδD values of the generated hydrocarbon gases and Ro values as well as amongδD values of the hydrocarbon gas species are established.The close relationships among these parameters suggest that the water medium had a significant effect on the hydrogen isotopic composition and a minimal effect on the carbon isotopic composition of the hydrocarbon gases.The results of these pyrolyses may provide information for the understanding of the genesis of coalbed gas from herbaceous marsh material with the participation of different diagenetic water media.展开更多
N^1,N^2-Bis[1-（2-hydroxyphenyl）methylidene]ethanedihydrazide（MEH） was used as new compound which plays the role of an excellent ion carrier in the fabrication of a Ho（Ⅲ） membrane electrode.The electrode shows a...N^1,N^2-Bis[1-（2-hydroxyphenyl）methylidene]ethanedihydrazide（MEH） was used as new compound which plays the role of an excellent ion carrier in the fabrication of a Ho（Ⅲ） membrane electrode.The electrode shows a good selectivity for Ho（Ⅲ） ion with respect to most common cations including alkali,alkaline earth,transition and heavy metal ions.This electrode has a wide linear dynamic range from 1.0×10^（-6） to 1.0×10^（-2） mol/L with a Nernstian slope of 19.8±0.3 mV per decade and a low detection limit of 5.8×10^（-7） mol/L in the pH range of 2.5-9.8,while the response time was rapid（10 s）.The suggested sensor was applied to the determination of Ho（Ⅲ） ions in tap water and river water samples.展开更多
A simple and versatile procedure for the combinatorial synthesis of（Z）-dialkyl-5-（alkylimino）-5Hspiro[furan-2,ll’-indeno[l,2-b]quinoxaline]-3,4-dicarboxylates via the catalyst-free one-pot fourcomponent reaction ...A simple and versatile procedure for the combinatorial synthesis of（Z）-dialkyl-5-（alkylimino）-5Hspiro[furan-2,ll’-indeno[l,2-b]quinoxaline]-3,4-dicarboxylates via the catalyst-free one-pot fourcomponent reaction of ninhydrin,benzene-l,2-diamines,dialkyl acetylenedicarboxylates and isocyanides is described.展开更多
A series of novel s-triazolothiadiazoles 3a-h were prepared by condensation reaction of substituted amino triazoles 1a-b with N-phethaloyl-L-amino acids 2a-d in the presence of the phosphoroxy chloride （POC13） as an...A series of novel s-triazolothiadiazoles 3a-h were prepared by condensation reaction of substituted amino triazoles 1a-b with N-phethaloyl-L-amino acids 2a-d in the presence of the phosphoroxy chloride （POC13） as an anhydrous reagent. The structure of all synthesized compounds was confirmed by IR, 1H NMR, arid 13C NMR spectroscopy.展开更多
Melamine-formaldehyde resin supported H~＋ is used as an efficient catalyst in the Pechmann condensation reaction of phenols withβ-ketoesters,in solvent-free media leading to the formation of coumarin derivatives usi...Melamine-formaldehyde resin supported H~＋ is used as an efficient catalyst in the Pechmann condensation reaction of phenols withβ-ketoesters,in solvent-free media leading to the formation of coumarin derivatives using conventional heating and microwave irradiation in excellent yields with good purity.展开更多
The cost of environmental analysis is becoming astronomically high at the global scale. One of the major trends in the respective research activities is the development of biotesting methods. Such methods, in addition...The cost of environmental analysis is becoming astronomically high at the global scale. One of the major trends in the respective research activities is the development of biotesting methods. Such methods, in addition to ecotoxicology, are highly demanded for environmental monitoring and ecological standardization. The development of biotesting in toxicology, however, is limited to the ＂battery of tests＂ paradigm, while environmental monitoring and ecological standardization are based on the ＂uniformity of measurements＂ paradigm. A ＂reference bioindicator＂ is proposed to harmonize these approaches. A reference bioindicator serves for comparison of data obtained by different bioindicators. This method was approved for the state environmental control. Application of reference bioindicators makes analytical procedure substantially cheaper. It requires, however, thorough calibration in relation to specific environmental factors （such as temperature, photoperiod etc.） as well as to specific active agents and their combinations. This problem can be solved with the start-up of calibrating analytical centers and long-term study of the effects of spatiotemporal environmental factors in specific areas and for specific reference objects. This paper demonstrates long-term study results for the surface waters of Pavlovsk reservoir （Bashkortostan, Russia）.展开更多
We demonstrate the fabrication of a new DNA sensor that is based on the optical interactions occurring between oligonucleotide-coated NaYF4:Yb^(3+);Er^(3+) upconversion nanoparticles and the two-dimensional dichalcoge...We demonstrate the fabrication of a new DNA sensor that is based on the optical interactions occurring between oligonucleotide-coated NaYF4:Yb^(3+);Er^(3+) upconversion nanoparticles and the two-dimensional dichalcogenide materials,MoS_(2) and WS_(2).Monodisperse upconversion nanoparticles were functionalized with single-stranded DNA endowing the nanoparticles with the ability to interact with the surface of the two-dimensional materials via van der Waals interactions leading to subsequent quenching of the upconversion fluorescence.By contrast,in the presence of a complementary oligonucleotide target and the formation of double-stranded DNA,the upconversion nanoparticles could not interact with MoS_(2) and WS_(2),thus retaining their inherent fluorescence properties.Utilizing this sensor we were able to detect target oligonucleotides with high sensitivity and specificity whilst reaching a concentration detection limit as low as 5 mol·L^(-1),within minutes.展开更多
文摘Assays that measure steroid hormones in patient care, public health, and research need to be both accurate and precise, as these criteria help to ensure comparability across all clinical and research applications. This review addresses major issues relevant to assay variability and describes recent activities by the US Centers for Disease Control and Prevention （CDC） to improve assay performance. Currently, high degrees of accuracy and precision are not always met for testosterone and estradiol measurements; although technologies for steroid hormone measurement have advanced significantly, measurement variability within and across laboratories has not improved accordingly. Differences in calibration and specificity are discussed as sources of variability in measurement accuracy. Ultimately, a combination of factors appears to cause inaccuracy of steroid hormone measurements, with nonuniform assay calibration and lack of specificity being two major contributors to assay variability. Within-assay variability for current assays is generally high, especially at low analyte concentrations. The CDC Hormone Standardization （HoSt） Program is improving clinical assays, as evidenced by a 50% decline in mean absolute bias between mass spectrometry assays and the CDC reference method from 2007 to 2011. This program provides the measurement traceability to CDC reference methods and helps to minimize factors affecting measurement variability.
文摘For much of the world＇s population, food is the major source of exposure to arsenic.Exposure to this non-essential metalloid at relatively low levels may be linked to a wide range of adverse health effects. Thus, evaluating foods as sources of exposure to arsenic is important in assessing risk and developing strategies that protect public health. Although most emphasis has been placed on inorganic arsenic as human carcinogen and toxicant, an array of arsenic-containing species are found in plants and animals used as foods. Here,we 2evaluate the contribution of complex organic arsenicals（arsenosugars, arsenolipids,and trimethylarsonium compounds） that are found in foods and consider their origins,metabolism, and potential toxicity. Commonalities in the metabolism of arsenosugars and arsenolipids lead to the production of di-methylated arsenicals which are known to exert many toxic effects. Evaluating foods as sources of exposure to these complex organic arsenicals and understanding the formation of reactive metabolites may be critical in assessing their contribution to aggregate exposure to arsenic.
基金North Tehran Branch,Islamic Azad University for their financial support
文摘A catalytic multi-component reaction involving aromatic amine,aromatic aldehydes,mercapto acid as substrates and Bi（SCH_2COOH）_3 as catalyst under solvent free conditions,afforded thiazolidin-4-one in good yields.The efficiency of the catalyst was proved with a variety of substrates,ranging from electrondeficient to electron-rich aldehydes.
基金supported by the National Natural Science Foundation of China(Grant nos.41772108 and 41472121)
文摘To understand the influence of the diagenetic water medium on the isotopic compositions of thermogenic coalbed gas,both hydrous and anhydrous closed-system pyrolyses were performed at temperatures of 250°C to 650°C on an herbaceous marsh peat.Compared to the results of anhydrous pyrolysis,the hydrocarbon gases generated from hydrous pyrolyses have very different hydrogen isotopic compositions.However,the carbon isotopic compositions of the hydrocarbon gases became only slightly heavier in hydrous pyrolysis,compared to that from anhydrous pyrolysis.With the progress of thermal evolution from peat to a more advanced thermal maturity of vitrinite reflectance values(Ro)of 5.5%during the pyrolysis,the difference in the averageδD value increased from 52‰to 64‰between the hydrous pyrolysis with saltwater and anhydrous pyrolysis and increased from 18‰to 29‰between the hydrous pyrolysis with freshwater and anhydrous pyrolysis,respectively.The difference in the averageδ^(13)C value was only 1‰–2‰between the hydrous and anhydrous pyrolysis.The relationships between theδD values of the generated hydrocarbon gases and Ro values as well as amongδD values of the hydrocarbon gas species are established.The close relationships among these parameters suggest that the water medium had a significant effect on the hydrogen isotopic composition and a minimal effect on the carbon isotopic composition of the hydrocarbon gases.The results of these pyrolyses may provide information for the understanding of the genesis of coalbed gas from herbaceous marsh material with the participation of different diagenetic water media.
文摘N^1,N^2-Bis[1-（2-hydroxyphenyl）methylidene]ethanedihydrazide（MEH） was used as new compound which plays the role of an excellent ion carrier in the fabrication of a Ho（Ⅲ） membrane electrode.The electrode shows a good selectivity for Ho（Ⅲ） ion with respect to most common cations including alkali,alkaline earth,transition and heavy metal ions.This electrode has a wide linear dynamic range from 1.0×10^（-6） to 1.0×10^（-2） mol/L with a Nernstian slope of 19.8±0.3 mV per decade and a low detection limit of 5.8×10^（-7） mol/L in the pH range of 2.5-9.8,while the response time was rapid（10 s）.The suggested sensor was applied to the determination of Ho（Ⅲ） ions in tap water and river water samples.
文摘A simple and versatile procedure for the combinatorial synthesis of（Z）-dialkyl-5-（alkylimino）-5Hspiro[furan-2,ll’-indeno[l,2-b]quinoxaline]-3,4-dicarboxylates via the catalyst-free one-pot fourcomponent reaction of ninhydrin,benzene-l,2-diamines,dialkyl acetylenedicarboxylates and isocyanides is described.
基金Malayer Branch,Islamic Azad University for their financial support
文摘A series of novel s-triazolothiadiazoles 3a-h were prepared by condensation reaction of substituted amino triazoles 1a-b with N-phethaloyl-L-amino acids 2a-d in the presence of the phosphoroxy chloride （POC13） as an anhydrous reagent. The structure of all synthesized compounds was confirmed by IR, 1H NMR, arid 13C NMR spectroscopy.
文摘Melamine-formaldehyde resin supported H~＋ is used as an efficient catalyst in the Pechmann condensation reaction of phenols withβ-ketoesters,in solvent-free media leading to the formation of coumarin derivatives using conventional heating and microwave irradiation in excellent yields with good purity.
文摘The cost of environmental analysis is becoming astronomically high at the global scale. One of the major trends in the respective research activities is the development of biotesting methods. Such methods, in addition to ecotoxicology, are highly demanded for environmental monitoring and ecological standardization. The development of biotesting in toxicology, however, is limited to the ＂battery of tests＂ paradigm, while environmental monitoring and ecological standardization are based on the ＂uniformity of measurements＂ paradigm. A ＂reference bioindicator＂ is proposed to harmonize these approaches. A reference bioindicator serves for comparison of data obtained by different bioindicators. This method was approved for the state environmental control. Application of reference bioindicators makes analytical procedure substantially cheaper. It requires, however, thorough calibration in relation to specific environmental factors （such as temperature, photoperiod etc.） as well as to specific active agents and their combinations. This problem can be solved with the start-up of calibrating analytical centers and long-term study of the effects of spatiotemporal environmental factors in specific areas and for specific reference objects. This paper demonstrates long-term study results for the surface waters of Pavlovsk reservoir （Bashkortostan, Russia）.
基金Antonios G.Kanaras,Otto L.Muskens and Davide Giust would like to acknowledge funding from BBSRC(Grant No.BB/N021150/1).
文摘We demonstrate the fabrication of a new DNA sensor that is based on the optical interactions occurring between oligonucleotide-coated NaYF4:Yb^(3+);Er^(3+) upconversion nanoparticles and the two-dimensional dichalcogenide materials,MoS_(2) and WS_(2).Monodisperse upconversion nanoparticles were functionalized with single-stranded DNA endowing the nanoparticles with the ability to interact with the surface of the two-dimensional materials via van der Waals interactions leading to subsequent quenching of the upconversion fluorescence.By contrast,in the presence of a complementary oligonucleotide target and the formation of double-stranded DNA,the upconversion nanoparticles could not interact with MoS_(2) and WS_(2),thus retaining their inherent fluorescence properties.Utilizing this sensor we were able to detect target oligonucleotides with high sensitivity and specificity whilst reaching a concentration detection limit as low as 5 mol·L^(-1),within minutes.
