The charge radius of the proton, the simplest nucleus, is known from electron-scattering experiments only with a surprisingly low precision of about 2%. The poor knowledge of the proton charge radius ...restricts tests of bound-state quantum electrodynamics (QED) to the precision level of about 6 × 10
6
, although the experimental data themselves (1S Lamb shift in hydrogen) have reached a precision of 2 × 10
6
. The determination of the proton charge radius with an accuracy of 10
3
is the main goal of our experiment, opening a way to check bound-state QED predictions to a level of 10
7
. The principle is to measure the 2S2P energy difference in muonic hydrogen (µ
p) by infrared laser spectroscopy. The first data were taken in the second half of 2003. Muons from our unique very-low-energy muon beam are stopped at a rate of ~100 s
1
in 0.6 mbar H
2
gas where the lifetime of the formed µp(2S) atoms is about 1.3 µs. An incoming muon triggers a pulsed multistage laser system that delivers ~0.2 mJ at λ ≈ 6 µm. Following the laser excitation µp(2S) → µp(2P) we observe the 1.9 keV X-rays from 2P1S transitions using large area avalanche photodiodes. The resonance frequency, and, hence, the Lamb shift and the proton radius, is determined by measuring the intensity of these X-rays as a function of the laser wavelength. A broad range of laser frequencies was scanned in 2003 and the analysis is currently under way.
PACS Nos.: 36.10.Dr, 14.20.Dh, 42.62.Fi
Accurate knowledge of the charge and Zemach radii of the proton is essential, not only for understanding its structure but also as input for tests of bound-state quantum electrodynamics and its ...predictions for the energy levels of hydrogen. These radii may be extracted from the laser spectroscopy of muonic hydrogen (μp, that is, a proton orbited by a muon). We measured the $2{\mathrm{S}}_{1/2}^{\mathrm{F}=0}-2{\mathrm{P}}_{3/2}^{\mathrm{F}=1}$ transition frequency in μp to be 54611.16(1.05) gigahertz (numbers in parentheses indicate one standard deviation of uncertainty) and reevaluated the $2{\mathrm{S}}_{1/2}^{\mathrm{F}=1}-2{\mathrm{P}}_{3/2}^{\mathrm{F}=1}$ transition frequency, yielding 49881.35(65) gigahertz. From the measurements, we determined the Zemach radius, r Z = 1.082(37) femtometers, and the magnetic radius, r M = 0.87(6) femtometer, of the proton. We also extracted the charge radius, r E = 0.84087(39) femtometer, with an order of magnitude more precision than the 2010-CODATA value and at 7σ variance with respect to it, thus reinforcing the proton radius puzzle.
The hypnozoite form of
Plasmodium vivax
malaria can lead to recrudescent infection months after primary infection. Primaquine is used as prophylaxis to prevent such relapses. In this report, a higher ...total dose of primaquine (7.0 mg per kilogram over 14 days) was found to be more efficacious than the standard total dose (3.5 mg per kilogram over 7 days).
•We describe FT-ICR MS analysis of asphaltene using different ionization sources.•LDI/MALDI facilitated clustering reactions to form characteristic fullerene ions.•The clusterization of asphaltenes ...showed a dependency on the laser power density.•APCI/APPI should be more suitable to access the chemical composition of asphaltene.
Asphaltenes analysis still remains a challenge due to their unknown molecular structure and self-associative behavior. FT-ICR MS analyses using five different ionization methods, ESI, APCI, APPI, LDI and MALDI, in both positive and negative mode were performed. A characteristic and typical behavior was observed for the experiments using LDI(±) and MALDI(±)FT-ICR analyses: a broadband mass spectrum ranging from m/z 500 to 3000 was observed with a 24Da interval. This phenomenon was attributed to fullerene cluster formation. The most abundant allotropic form of fullerene, C60, was observed at m/z 719.99914. These species were not observed in APCI(+)/APPI(+) analyses. This last analysis of asphaltene samples doped with the C60 solution promptly reveals the typical fullerene ions. LDI(+) analyses of pure C60 showed condensation products. These results indicate a clusterization of asphaltenes in the LDI/MALDI plume, which showed a highly dependency on the laser power density. The dispersion of LDI results on carbonaceus samples in the literature is associated with the lack of control of these parameters. However, to access the sample composition, APPI and APCI should be more suitable.
The aim of this study was to evaluate the therapeutic effects of ultrasound (US)-mediated phonophoresis alone or in association with diclofenac diethylammonium (DCF) administered topically in animal ...models of inflammation. A pre-clinical, prospective, and randomized experimental study of quantitative and qualitative nature was carried out. Phonophoresis was performed using a therapeutic ultrasound apparatus in two distinct models of acute inflammation. Edema was induced by an intraplantar injection of carrageenan and measured by plethysmography. The Hargreaves test was used to evaluate the antinociceptive activity and investigate the action of phonophoresis on tumor necrosis factor (TNF)-α production. A histological analysis with hematoxylin-eosin was used to evaluate tissue repair, and the expression of COX-2 was determined by immunohistochemical analysis. At the peak of inflammatory activity (3 h), treatment with US, US+DCF, and DCF significantly reduced edema formation compared to the control group. Treatment with US+DCF was more effective than treatment with US alone at both analyzed times. In the analysis of the antinociceptive activity, the treatments significantly increased the latency time in response to the thermal stimulus. Histopathological analysis revealed a reduction of the inflammatory infiltrates and immunohistochemistry demonstrated that the association was effective in reducing COX-2 expression compared to the control group. The association of DCF with US produced anti-inflammatory and antinociceptive effects in rat models of inflammation, which may be associated with inhibition of COX-2 and TNF-α production.
The Lamb-shift experiment in muonic hydrogen (μ
-
p) aims to measure the energy difference between the
atomic levels to a precision of 30 ppm. This would allow the r.m.s. proton charge radius r
p
to ...be deduced to a precision of 10
-3
and open a way to check bound-state quantum electrodynamics (QED) to a level of 10
-7
. The poor knowledge of the proton charge radius restricts tests of bound-state QED to the precision level of about 6 × 10
-6
, although the experimental data themselves (Lamb-shift in hydrogen) have reached a precision of × 10
-6
. Values for r
p
not depending on bound-state QED results from electron scattering experiments have a surprisingly large uncertainty of 2%. In our Lamb-shift experiment, low-energy negative muons are stopped in low-density hydrogen gas, where, following the μ
-
atomic capture and cascade, 1% of the muonic hydrogen atoms form the metastable 2S state with a lifetime of about 1 μs. A laser pulse at λ ≈ 6 μm is used to drive the 2S → 2P transition. Following the laser excitation, we observe the 1.9 keV X-ray being emitted during the subsequent de-excitation to the 1S state using large-area avalanche photodiodes. The resonance frequency and, hence, the Lamb shift and the proton charge radius are determined by measuring the intensity of the X-ray fluorescence as a function of the laser wavelength. The results of the run in December 2003 were negative but, nevertheless, promising. One by-product of the 2003 run was the first observation of the short-lived 2S component in muonic hydrogen. Currently, improvements in the laser-system, the experimental apparatus, and the data acquisition are being implemented. PACS Nos.: 36.10.Dr, 14.20.Dh, 42.62.Fi
Processing of cassava roots to remove cyanogens Cardoso, A.Paula; Mirione, Estevao; Ernesto, Mario ...
Journal of food composition and analysis,
08/2005, Letnik:
18, Številka:
5
Journal Article
Recenzirano
A simple equation is developed between the total cyanide contents of cassava root parenchyma and the processed product with the % retention of cyanide on processing. This equation is applied to ...different methods of processing used worldwide. Thus to produce cassava flour of 10
mg HCN equivalents/kg flour (ppm), the WHO safe level, by sun drying or heap fermentation requires starting with sweet cassava containing 12–32
ppm total cyanide. In an average year only 14% of flour samples in our study areas in Nampula Province of Mozambique had total cyanide contents of <10
ppm. Distribution curves of flour total cyanide show that the percentage of samples exceeding 100
ppm total cyanide increased from 6% in an average year to 43–65% in a low rainfall year, when cases of konzo also occurred.
Processing methods used to produce farinha in Brazil and gari in West Africa reduce the total cyanide content to less than one eighth of that using heap fermentation and less than one sixteenth of that using sun drying. Heap fermentation and sun drying, commonly used in eastern and southern Africa, do not adequately remove cyanide in a normal year and are hopelessly inadequate when used on cassava grown during drought. New and greatly improved processing methods are urgently needed. The high levels of cyanide intake in central, eastern and southern Africa from high cyanide flour are the most likely cause of konzo in young people and the very long term consumption of gari of lower cyanide content in West Africa is the most likely cause of TAN in older people.
We plan to measure several 2S -2P transition frequencies in ... and ... by means of laser spectroscopy with an accuracy of 50 ppm. This will lead to a determination of the corresponding nuclear rms ...charge radii with a relative accuracy of 3 x 10..., limited by the uncertainty of the nuclear polarization contribution. First, these measurements will help to solve the proton radius puzzle. Second, these very precise nuclear radii are benchmarks for ab initio few-nucleon theories and potentials. Finally when combined with an ongoing measurement of the 1S - 2S transition in He+, these measurements will lead to an enhanced bound-state QED test of the 1S Lamb shift in He+. (ProQuest: ... denotes formulae/symbols omitted.)
FSH Directly Regulates Bone Mass Sun, Li; Peng, Yuanzhen; Sharrow, Allison C. ...
Cell,
04/2006, Letnik:
125, Številka:
2
Journal Article
Recenzirano
Odprti dostop
Postmenopausal osteoporosis, a global public health problem, has for decades been attributed solely to declining estrogen levels. Although FSH levels rise sharply in parallel, a direct effect of FSH ...on the skeleton has never been explored. We show that FSH is required for hypogonadal bone loss. Neither FSHβ nor FSH receptor (FSHR) null mice have bone loss despite severe hypogonadism. Bone mass is increased and osteoclastic resorption is decreased in haploinsufficient FSHβ
+/− mice with normal ovarian function, suggesting that the skeletal action of FSH is estrogen independent. Osteoclasts and their precursors possess G
i2α-coupled FSHRs that activate MEK/Erk, NF-κB, and Akt to result in enhanced osteoclast formation and function. We suggest that high circulating FSH causes hypogonadal bone loss.
Alternative binders to cobalt, based on stainless steel (SS, AISI304) and copper were investigated for tungsten carbide (WC) based cemented carbides. The binder content was fixed at 12 wt%, and the ...Cu:SS ratio varied in proportions of 0:1, 1:5, 1:2, 1:1, 1:0. High energy ball milling was applied to ensure high homogenization, nanometric particle size and mechanical alloying of binder elements in the powders' mixtures. To assess an adequate sintering route, wettability testing and constant heating rate dilatometry in vacuum were performed. The composites were analyzed in terms of their structural, microstructural and mechanical characteristics.
The poor wettability of melted Cu on WC surfaces was increased by alloying it with SS and highly dense compacts could be successfully attained at reduced vacuum sintering temperatures with binders having a Cu:SS ratio equal to or lower than 1:2. The microstructures show secondary phases and significant grain coarsening during sintering, whereas the average grain size was kept in the nanometric range. The composites that attained almost full densification present high hardness, comparable to that of nanometric WC-12Co cemented carbides processed by similar routes, but lower toughness values.
Display omitted
•Alloying Cu with stainless steel by HEBM increases the wettability of Cu on WC.•WC - (Cu, Fe, Cr, Ni) nanopowders can be successfully densified at reduced temperatures.•WC - (Cu, Fe, Cr, Ni) nanocomposites present high hardness and moderate toughness.
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