排序方式: 共有93条查询结果,搜索用时 31 毫秒
1.
Gies P Roy C McLennan A Pailthorpe M Hilfiker R Osterwalder U Monard B Moseley H Sliney D Wengraitis S Wong J Human S Bilimis Z Holmes G 《Photochemistry and photobiology》2003,77(1):58-67
In recent years the need to standardize measurement protocols for quantifying the degree of ultraviolet radiation (UVR) protection provided by clothing has led to the introduction of a number of standards around the world. To date, these standards have specified spectral measurements of UVR transmission by clothing and fabrics. Development of a standard test method has become an important part of the testing process, and this article presents results from an intercomparison involving 10 independent testing laboratories and 11 different UVR transmission measurement instruments. In addition to comparing the measured ultraviolet protection factors (UPF), this intercomparison also incorporates detailed scan results from all 10 laboratories and highlights differences in performance of the various instruments in different wavelength regions. Careful examination of these differences can indicate where changes to the systems could be made to allow improvements both in equipment performance and in agreement of the final results. The variability in the measurements of UPF in this study suggest that the protection categories in standards may need to be broadened. 相似文献
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Juliana Marques Ramos Thiago Martucci Artur Wilson Carbonari Messias de Souza Costa Rajendra Narain Saxena Reiner Vianden 《Hyperfine Interactions》2013,221(1-3):129-136
Electric quadrupole interactions were studied in pure and Mn-doped powder samples and thin films of SnO2 using perturbed γγ angular correlation spectroscopy (PAC). The powder samples were prepared by Sol gel method and the thin film were prepared on the Si (100) substrate by sputtering technique using Sn in the oxygen atmosphere. The samples were characterized by x-ray diffraction, energy dispersive spectroscopy and scanning electron microscopy. The thickness of the film was 100 nm. The average particle size of the SnO2 powder samples was determined to be smaller than 60 nm. The radioactive 111In and 181Hf tracers were introduced in the powder samples during the sol gel chemical process. Radioactive 111In was implanted on the SnO2 thin films using the University of Bonn ion implanter (BONIS). PAC measurements were carried out in a four BaF2 detector spectrometer in the temperature range of 77–973 K for samples annealed at different temperatures. The PAC results for both nuclear probes show the presence of two electric quadrupole interactions. The major fractions in both cases correspond to the substitutional sites in the rutile phase of SnO2. The results are compared with previous PAC measurements. 相似文献
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Francesco Berto 《Metaphysica》2008,9(2):205-218
Drawing on different suggestions from the literature, we outline a unified metaphysical framework, labeled as Modal Meinongian Metaphysics (MMM), combining Meinongian themes with a non-standard modal ontology. The MMM approach is based on (1) a comprehension principle (CP) for objects in unrestricted, but qualified form, and (2) the employment of an ontology of impossible worlds, besides possible ones. In §§1–2, we introduce the classical Meinongian metaphysics and consider two famous Russellian criticisms, namely (a) the charge of inconsistency and (b) the claim that naïve Meinongianism allows one to prove that anything exists. In §3, we have impossible worlds enter the stage and provide independent justification for their use. In §4, we introduce our revised comprehension principle: our CP has no restriction on the (sets of) properties that can characterize objects, but parameterizes them to worlds, therefore having modality explicitly built into it. In §5, we propose an application of the MMM apparatus to fictional objects and defend the naturalness of our treatment against alternative approaches. Finally, in §6, we consider David Lewis’ notorious objection to impossibilia, and provide a reply to it by resorting to an ersatz account of worlds. 相似文献
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Tatjana Souza Lima Keesen Larisse Virgolino da Silva Juliana da Câmara Rocha Luciana Nalone Andrade Tamires Cardoso Lima 《Natural product research》2019,33(17):2536-2540
Leishmaniasis belongs to a complex of zoonotic disease caused by protozoa of the genus Leishmania and is considered a major public health problem. Several essential oil chemical components have inhibitory effect against protozoa, including Leishmania donovani. Thus, the aim of this study was to evaluate for the first time the anti-Leishmania activity of two p-menthane monoterpene isomers (EPER-1: perillaldehyde 1,2-epoxide and EPER-2: perillaldehyde 8,9-epoxide) against L. donovani promastigotes as well as evaluating cytotoxic effect on mononuclear peripheral blood cells. Results of anti-Leishmania assay revealed that EPER-2 (IC50 = 3.8 μg.mL?1) was 16-fold more potent than its isomer EPER-1 (IC50 = 64.6 μg.mL?1). In contrast to PBMC cells, EPER-2 was not cytotoxic (IC50 > 400 μg.mL?1) when compared to positive control. These data suggest that the disposition of epoxide group into the p-menthane skeleton affects the anti-Leishmania activity, being that the presence of the exocyclic epoxide group considerably increased potency. Thus, it was possible to observe that the location of the epoxide group into the p-menthane skeleton resulted in different potencies. 相似文献
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Prenesti E Fisicaro P Berto S Ferrara E Daniele PG 《Analytical and bioanalytical chemistry》2007,387(7):2595-2600
This paper reports evaluation of the behaviour of different combined glass electrodes applied to measurement of the pH of
a primary, 0.01 mol kg−1, tetraborate buffer. Measurements were first performed by use of a primary Harned cell (at 15, 25, and 37 °C); these results
were then compared with those obtained for the same solution by use of three combined glass electrodes (25 °C) with different
membranes and liquid-junction designs, calibrated by use of commercial pH-metric buffers. The pH of the same solution was
also measured in terms of the molal concentration of hydrogen ions, using acid–base titration to evaluate the formal potential
difference K of each cell at fixed ionic strength, I, adjusted by addition of KCl or Et4NI (tetraethylammonium iodide). The reference value from primary measurement, paH = 9.171, was slightly closer to the mean value obtained by determination of concentration, rather than that obtained by
direct measurement of activity; the differences were smaller than the extended uncertainty characteristics of the secondary
measurements. The importance of evaluation of the ionic strength of the solution under study is emphasised. We verified that
for tetraborate buffer slight modification of the value of I used to calculate γ
i
(the activity coefficient of a single ion) in the calculation of paH from the acidity function at zero molality of chloride can significantly affect the reference value of the calibrator tool.
This is true, in general, for low values of the ionic strength, such as those considered in this work; an approximate value
of I can then cause distortions along the pH traceability chain. Application of the concepts of thermodynamics to this traceability
chain is discussed. 相似文献
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Arlindo Csar Matias Pereira Helison de Oliveira Carvalho Danna Emanuelle Santos Gonalves Karyny Roberta Tavares Picano Abraho Victor Tavares de Lima Teixeira dos Santos Heitor Ribeiro da Silva Francinaldo Sarges Braga Roberto Messias Bezerra Alessandro de Sousa Nunes Maira Tiyomi Sacata Tongo Nazima Júlia Gomes Cerqueira Talisson Taglialegna Janayra Maris Teixeira Jos Carlos Tavares Carvalho 《Molecules (Basel, Switzerland)》2021,26(16)
This study aimed to evaluate and compare the effects of co-treatment with purified annatto oil (PAO) or its granules (GRA, Chronic®) with that of testosterone on the orchiectomy-induced osteoporosis in Wistar rats. After surgery, rats were treated from day 7 until day 45 with testosterone only (TES, 7 mg/kg, IM) or TES + PAO or GRA (200 mg/kg, p.o.). The following parameters were evaluated: food/water intake, weight, HDL, LDL, glucose, triglycerides (TG), total cholesterol (TC), alkaline phosphatase levels, blood phosphorus and calcium contents, femur weight, structure (through scanning electron microscopy), and calcium content (through atomic absorption spectrophotometry). Our results show that orchiectomy could significantly change the blood lipid profile and decrease bone integrity parameters. Testosterone reposition alone could improve some endpoints, including LDL, TC, bone weight, and bone calcium concentration. However, other parameters were not significantly improved. Co-treatment with PAO or GRA improved the blood lipid profile and bone integrity more significantly and improved some endpoints not affected by testosterone reposition alone (such as TG levels and trabeculae sizes). The results suggest that co-treatment with annatto products improved the blood lipid profile and the anti-osteoporosis effects of testosterone. Overall, GRA had better results than PAO. 相似文献
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Natural sediments show sequestering properties that can lead to a process of self-purification of aquatic environment from metal pollution. The study of the interaction between metal ions and sediment particles enhances what is known about the distribution and bioavailability of heavy metals in natural systems. Our contribution concerns the characterisation of the sequestering ability of a River Po sediment with regard to calcium(II), magnesium(II), cadmium(II), nickel(II) and copper(II), in fixed experimental conditions, through pH-metric and spectrometric measurements. A batch titration procedure was adopted and, in each solution, after equilibration, both pH and pM (M = Ca(II), Mg(II), Cd(II), Ni(II), Cu(II)) (via Inductively Coupled Plasma - Optical Emission Spectroscopy, ICP-OES) values were measured. The experimental data were first processed with a specific software to evaluate the concentration and protonation constants of the sediment ligand site(s). The speciation model was then assessed, together with the values of complexation constants, for the different sediment/metal cation systems. In order to better characterise the copper(II)-sediment interaction and to obtain more information about the nature of ligand site(s) involved, EPR (Electronic Paramagnetic Resonance) measurements were also made on the dry sediment before and after reaction with copper(II) ions. 相似文献
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Brgles M Bertoša B Winkler W Kurtović T Allmaier G Marchetti-Deschmann M Halassy B 《Analytical and bioanalytical chemistry》2012,402(9):2737-2748
The ammodytoxins (Atxs) are neurotoxic phospholipases which occur in Vipera ammodytes ammodytes (Vaa) snake venom. There are three Atx isoforms, A, B, and C, which differ in only five amino acid positions at the C-terminus
but differ substantially in their toxicity. The objective of this study was to establish an analytical method for unambiguous
identification of all three isoforms and to use the method to assess a procedure for purification of the most toxic phospholipase,
AtxA, from the venom. Isolation procedure for AtxA consisted of isolation of Atx-cross-reactive material (proteins recognized
by anti-Atx antibodies), by use of an affinity column, then cation exchange on CIM (Convective Interaction Media) disks. The
purification procedure was monitored by means of reversed-phase chromatography (RPC) and mass spectrometry (MS). Although
previous cation exchange of the pure isoforms enabled separate elution of AtxA from B and C, separation of AtxA from Atxs
mixture was not accomplished. RPC was not able to separate the Atx isoforms, whereas an MS based approach proved to be more
powerful. Peptides resulting from tryptic digestion of Atxs which enable differentiation between the three isoforms were successfully
detected and their sequences were confirmed by post-source decay (PSD) fragmentation. Separation of Atx isoforms by ion-exchange
chromatography is most presumably prevented by Atxs heterodimer formation. The tendency of Atxs to form homodimers and heterodimers
of similar stability was confirmed by molecular modeling. 相似文献