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1

Optimizing the Delivery of Short-Lived Alpha Particle-Emitting Isotopes to Solid Tumors  

SciTech Connect

The underlying hypothesis of this project was that optimal alpha emitter-based radioimmunotherapy (RAIT) could be achieved by pairing the physical half-life of the radioisotope to the biological half-life of the targeting vehicle. The project had two specific aims. The first aim was to create and optimize the therapeutic efficacy of 211At-SAPS-C6.5 diabody conjugates. The second aim was to develop bispecific-targeting strategies that increase the specificity and efficacy of alpha-emitter-based RAIT. In the performance of the first aim, we created 211At-SAPS-C6.5 diabody conjugates that specifically targeted the HER2 tumor associated antigen. In evaluating these immunoconjugates we determined that they were capable of efficient tumor targeting and therapeutic efficacy of established human tumor xenografts growing in immunodeficient mice. We also determined that therapeutic doses were associated with late renal toxicity, likely due to the role of the kidneys in the systemic elimination o f these agents. We are currently performing more studies focused on better understanding the observed toxicity. In the second aim, we successfully generated bispecific single-chain Fv (bs-scFv) molecules that co-targeted HER2 and HER3 or HER2 and HER4. The in vitro kinetics and in vivo tumor-targeting properties of these molecules were evaluated. These studies revealed that the bs-scFv molecules selectively localized in vitro on tumor cells that expressed both antigens and were capable of effective tumor localization in in vivo studies.

Adams, Gregory P.

2004-11-24

2

Radioimmunotherapy with alpha-particle emitting radionuclides.  

PubMed

An important consideration in the development of effective strategies for radioimmunotherapy is the nature of the radiation emitted by the radionuclide. Radionuclides decaying by the emission of alpha-particles offer the possibility of matching the cell specific reactivity of monoclonal antibodies with radiation with a range of only a few cell diameters. Furthermore, alpha-particles have important biological advantages compared with external beam radiation and beta-particles including a higher biological effectiveness, which is nearly independent of oxygen concentration, dose rate and cell cycle position. In this review, the clinical settings most likely to benefit from alpha-particle radioimmunotherapy will be discussed. The current status of preclinical and clinical research with antibodies labeled with 3 promising alpha-particle emitting radionuclides - (213)Bi, (225)Ac, and (211)At - also will be summarized. PMID:15640792

Zalutsky, M R; Pozzi, O R

2004-12-01

3

Enhanced retention of the alpha-particle-emitting daughters of Actinium-225 by liposome carriers.  

PubMed

Targeted alpha-particle emitters hold great promise as therapeutics for micrometastatic disease. Because of their high energy deposition and short range, tumor targeted alpha-particles can result in high cancer-cell killing with minimal normal-tissue irradiation. Actinium-225 is a potential generator for alpha-particle therapy: it decays with a 10-day half-life and generates three alpha-particle-emitting daughters. Retention of (225)Ac daughters at the target increases efficacy; escape and distribution throughout the body increases toxicity. During circulation, molecular carriers conjugated to (225)Ac cannot retain any of the daughters. We previously proposed liposomal encapsulation of (225)Ac to retain the daughters, whose retention was shown to be liposome-size dependent. However, daughter retention was lower than expected: 22% of theoretical maximum decreasing to 14%, partially due to the binding of (225)Ac to the phospholipid membrane. In this study, Multivesicular liposomes (MUVELs) composed of different phospholipids were developed to increase daughter retention. MUVELs are large liposomes with entrapped smaller lipid-vesicles containing (225)Ac. PEGylated MUVELs stably retained over time 98% of encapsulated (225)Ac. Retention of (213)Bi, the last daughter, was 31% of the theoretical maximum retention of (213)Bi for the liposome sizes studied. MUVELs were conjugated to an anti-HER2/neu antibody (immunolabeled MUVELs) and were evaluated in vitro with SKOV3-NMP2 ovarian cancer cells, exhibiting significant cellular internalization (83%). This work demonstrates that immunolabeled MUVELs might be able to deliver higher fractions of generated alpha-particles per targeted (225)Ac compared to the relative fractions of alpha-particles delivered by (225)Ac-labeled molecular carriers. PMID:17935286

Sofou, Stavroula; Kappel, Barry J; Jaggi, Jaspreet S; McDevitt, Michael R; Scheinberg, David A; Sgouros, George

2007-10-13

4

Thorium and actinium polyphosphonate compounds as bone-seeking alpha particle-emitting agents.  

PubMed

The present study explores the use of alpha-particle-emitting, bone-seeking agents as candidates for targeted radiotherapy. Actinium and thorium 1,4,7,10 tetraazacyclododecane N,N',N'',N''' 1,4,7,10-tetra(methylene) phosphonic acid (DOTMP) and thorium-diethylene triamine N,N',N'' penta(methylene) phosphonic acid (DTMP) were prepared and their biodistribution evaluated in conventional Balb/C mice at four hours after injection. All three bone-seeking agents showed a high uptake in bone and a low uptake in soft tissues. Among the soft tissue organs, only kidney had a relatively high uptake. The femur/kidney ratios for 227Th-DTMP, 228-Ac-DOTMP and 227Th-DOTMP were 14.2, 7.6 and 6.0, respectively. A higher liver uptake of 228Ac-DOTMP was seen than for 227Th-DTMP and 227Th-DOTMP. This suggests that some demetallation of the 228Ac-DOTMP complex had occurred. The results indicate that 225Ac-DOTMP, 227Th-DOTMP and 227Th-DTMP have promising properties as potential therapeutic bone-seeking agents. PMID:15015582

Henriksen, Gjermund; Bruland, Oyvind S; Larsen, Roy H

5

Renal tubulointerstitial changes after internal irradiation with alpha-particle-emitting actinium daughters.  

PubMed

The effect of external gamma irradiation on the kidneys is well described. However, the mechanisms of radiation nephropathy as a consequence of targeted radionuclide therapies are poorly understood. The functional and morphologic changes were studied chronologically (from 10 to 40 wk) in mouse kidneys after injection with an actinium-225 (225Ac) nanogenerator, a molecular-sized, antibody-targeted, in vivo generator of alpha-particle-emitting elements. Renal irradiation from free, radioactive daughters of 225Ac led to time-dependent reduction in renal function manifesting as increase in blood urea nitrogen. The histopathologic changes corresponded with the decline in renal function. Glomerular, tubular, and endothelial cell nuclear pleomorphism and focal tubular cell injury, lysis, and karyorrhexis were observed as early as 10 wk. Progressive thinning of the cortex as a result of widespread tubulolysis, collapsed tubules, glomerular crowding, decrease in glomerular cellularity, interstitial inflammation, and an elevated juxtaglomerular cell count were noted at 20 to 30 wk after treatment. By 35 to 40 wk, regeneration of simplified tubules with tubular atrophy and loss with focal, mild interstitial fibrosis had occurred. A lower juxtaglomerular cell count with focal cytoplasmic vacuolization, suggesting increased degranulation, was also observed in this period. A focal increase in tubular and interstitial cell TGF-beta1 expression starting at 20 wk, peaking at 25 wk, and later declining in intensity with mild increase in the extracellular matrix deposition was noticed. These findings suggest that internally delivered alpha-particle irradiation-induced loss of tubular epithelial cells triggers a chain of adaptive changes that result in progressive renal parenchymal damage accompanied by a loss of renal function. These findings are dissimilar to those seen after gamma or beta irradiation of kidneys. PMID:15987754

Jaggi, Jaspreet Singh; Seshan, Surya V; McDevitt, Michael R; LaPerle, Krista; Sgouros, George; Scheinberg, David A

2005-06-29

6

Bismuth212-labeled anti-Tac monoclonal antibody: alpha-particle-emitting radionuclides as modalities for radioimmunotherapy  

Microsoft Academic Search

Anti-Tac, a monoclonal antibody directed to the human interleukin 2 (IL-2) receptor, has been successfully conjugated to the alpha-particle-emitting radionuclide bismuth-212 by use of a bifunctional ligand, the isobutylcarboxycarbonic anhydride of diethylenetriaminepentaacetic acid. The physical properties of 212Bi are appropriate for radioimmunotherapy in that it has a short half-life, deposits its high energy over a short distance, and can be

R. W. Kozak; R. W. Atcher; O. A. Gansow; A. M. Friedman; J. J. Hines; T. A. Waldmann

1986-01-01

7

Bremsstrahlung in {alpha} Decay of {sup 210}Po: Do {alpha} Particles Emit Photons in Tunneling?  

SciTech Connect

Emission probability of bremsstrahlung in the {alpha} decay of {sup 210}Po was measured in {alpha} -{gamma} coincidence measurements with Si and Ge detectors. It was found that the bremsstrahlung yields are much smaller than those predicted by a Coulomb acceleration model, in which {gamma} rays are emitted during acceleration outside the barrier. This suggests that the radiation amplitude in the barrier cannot be neglected, and the discussion based on a quasiclassical approach is given. {copyright} {ital 1997} {ital The American Physical Society}

Kasagi, J.; Yamazaki, H.; Kasajima, N.; Ohtsuki, T.; Yuki, H. [Laboratory of Nuclear Science, Tohoku University, Mikamine, Taihaku, Sendai 982 (Japan)

1997-07-01

8

Treatment of solid tumors by interstitial release of recoiling short-lived alpha emitters  

NASA Astrophysics Data System (ADS)

A new method utilizing alpha particles to treat solid tumors is presented. Tumors are treated with interstitial radioactive sources which continually release short-lived alpha emitting atoms from their surface. The atoms disperse inside the tumor, delivering a high dose through their alpha decays. We implement this scheme using thin wire sources impregnated with 224Ra, which release by recoil 220Rn, 216Po and 212Pb atoms. This work aims to demonstrate the feasibility of our method by measuring the activity patterns of the released radionuclides in experimental tumors. Sources carrying 224Ra activities in the range 10-130 kBq were used in experiments on murine squamous cell carcinoma tumors. These included gamma spectroscopy of the dissected tumors and major organs, Fuji-plate autoradiography of histological tumor sections and tissue damage detection by Hematoxylin-Eosin staining. The measurements focused on 212Pb and 212Bi. The 220Rn/216Po distribution was treated theoretically using a simple diffusion model. A simplified scheme was used to convert measured 212Pb activities to absorbed dose estimates. Both physical and histological measurements confirmed the formation of a 5-7 mm diameter necrotic region receiving a therapeutic alpha-particle dose around the source. The necrotic regions shape closely corresponded to the measured activity patterns. 212Pb was found to leave the tumor through the blood at a rate which decreased with tumor mass. Our results suggest that the proposed method, termed DART (diffusing alpha-emitters radiation therapy), may potentially be useful for the treatment of human patients.

Arazi, L.; Cooks, T.; Schmidt, M.; Keisari, Y.; Kelson, I.

2007-08-01

9

Treatment of solid tumors by interstitial release of recoiling short-lived alpha emitters.  

PubMed

A new method utilizing alpha particles to treat solid tumors is presented. Tumors are treated with interstitial radioactive sources which continually release short-lived alpha emitting atoms from their surface. The atoms disperse inside the tumor, delivering a high dose through their alpha decays. We implement this scheme using thin wire sources impregnated with (224)Ra, which release by recoil (220)Rn, (216)Po and (212)Pb atoms. This work aims to demonstrate the feasibility of our method by measuring the activity patterns of the released radionuclides in experimental tumors. Sources carrying (224)Ra activities in the range 10-130 kBq were used in experiments on murine squamous cell carcinoma tumors. These included gamma spectroscopy of the dissected tumors and major organs, Fuji-plate autoradiography of histological tumor sections and tissue damage detection by Hematoxylin-Eosin staining. The measurements focused on (212)Pb and (212)Bi. The (220)Rn/(216)Po distribution was treated theoretically using a simple diffusion model. A simplified scheme was used to convert measured (212)Pb activities to absorbed dose estimates. Both physical and histological measurements confirmed the formation of a 5-7 mm diameter necrotic region receiving a therapeutic alpha-particle dose around the source. The necrotic regions shape closely corresponded to the measured activity patterns. (212)Pb was found to leave the tumor through the blood at a rate which decreased with tumor mass. Our results suggest that the proposed method, termed DART (diffusing alpha-emitters radiation therapy), may potentially be useful for the treatment of human patients. PMID:17671351

Arazi, L; Cooks, T; Schmidt, M; Keisari, Y; Kelson, I

2007-08-01

10

Alpha-particle emitting 213Bi-anti-EGFR immunoconjugates eradicate tumor cells independent of oxygenation.  

PubMed

Hypoxia is a central problem in tumor treatment because hypoxic cells are less sensitive to chemo- and radiotherapy than normoxic cells. Radioresistance of hypoxic tumor cells is due to reduced sensitivity towards low Linear Energy Transfer (LET) radiation. High LET ?-emitters are thought to eradicate tumor cells independent of cellular oxygenation. Therefore, the aim of this study was to demonstrate that cell-bound ?-particle emitting (213)Bi immunoconjugates kill hypoxic and normoxic CAL33 tumor cells with identical efficiency. For that purpose CAL33 cells were incubated with (213)Bi-anti-EGFR-MAb or irradiated with photons with a nominal energy of 6 MeV both under hypoxic and normoxic conditions. Oxygenation of cells was checked via the hypoxia-associated marker HIF-1?. Survival of cells was analysed using the clonogenic assay. Cell viability was monitored with the WST colorimetric assay. Results were evaluated statistically using a t-test and a Generalized Linear Mixed Model (GLMM). Survival and viability of CAL33 cells decreased both after incubation with increasing (213)Bi-anti-EGFR-MAb activity concentrations (9.25 kBq/ml-1.48 MBq/ml) and irradiation with increasing doses of photons (0.5-12 Gy). Following photon irradiation survival and viability of normoxic cells were significantly lower than those of hypoxic cells at all doses analysed. In contrast, cell death induced by (213)Bi-anti-EGFR-MAb turned out to be independent of cellular oxygenation. These results demonstrate that ?-particle emitting (213)Bi-immunoconjugates eradicate hypoxic tumor cells as effective as normoxic cells. Therefore, (213)Bi-radioimmunotherapy seems to be an appropriate strategy for treatment of hypoxic tumors. PMID:23724085

Wulbrand, Christian; Seidl, Christof; Gaertner, Florian C; Bruchertseifer, Frank; Morgenstern, Alfred; Essler, Markus; Senekowitsch-Schmidtke, Reingard

2013-05-28

11

Bismuth-212-labeled anti-Tac monoclonal antibody: alpha-particle-emitting radionuclides as modalities for radioimmunotherapy  

SciTech Connect

Anti-Tac, a monoclonal antibody directed to the human interleukin 2 (IL-2) receptor, has been successfully conjugated to the alpha-particle-emitting radionuclide bismuth-212 by use of a bifunctional ligand, the isobutylcarboxycarbonic anhydride of diethylenetriaminepentaacetic acid. The physical properties of 212Bi are appropriate for radioimmunotherapy in that it has a short half-life, deposits its high energy over a short distance, and can be obtained in large quantities from a radium generator. Antibody specific activities of 1-40 microCi/microgram (1 Ci = 37 GBq) were achieved. Specificity of the 212Bi-labeled anti-Tac was demonstrated for the IL-2 receptor-positive adult T-cell leukemia line HUT-102B2 by protein synthesis inhibition and clonogenic assays. Activity levels of 0.5 microCi or the equivalent of 12 rad/ml of alpha radiation targeted by anti-Tac eliminated greater than 98% the proliferative capabilities of HUT-102B2 cells with more modest effects on IL-2 receptor-negative cell lines. Specific cytotoxicity was blocked by excess unlabeled anti-Tac but not by human IgG. In addition, an irrelevant control monoclonal antibody of the same isotype labeled with 212Bi was unable to target alpha radiation to cell lines. Therefore, 212Bi-labeled anti-Tac is a potentially effective and specific immunocytotoxic reagent for the elimination of IL-2 receptor-positive cells. These experiments thus provide the scientific basis for use of alpha-particle-emitting radionuclides in immunotherapy.

Kozak, R.W.; Atcher, R.W.; Gansow, O.A.; Friedman, A.M.; Hines, J.J.; Waldmann, T.A.

1986-01-01

12

Temporal change in microdosimetry to bone marrow and stromal progenitor cells from alpha-particle-emitting radionuclides incorporated in bone.  

PubMed

The microdistributions of the alpha-particle-emitting bone surface-seeking radionuclides (239)Pu, (241)Am and (233)U in the mouse femoral shaft have been studied using computer-based image analysis of neutron-induced and alpha-particle track autoradiographs, prepared from femora of CBA/H mice which had been injected with 40 kBq kg(-1) of radionuclide (as citrate solution) at times from 1 to 448 days previously. Employing dosimetric methods, radiation dose rates and cumulative radiation doses to regions of the bone marrow thought to contain hemopoietic and stromal progenitor cells susceptible to neoplastic transformation to leukemia and osteosarcomas have been calculated. It has been shown that the three radionuclides differ in their relative deposition on the bone surfaces, and that patterns of changing redistribution with time are also varied. For stromal progenitor cells, which are thought to be targets for induction of osteosarcoma and are found in proximity to the bone surfaces, cumulative doses showed the trend (239)Pu > (241)Am > (233)U, correlating well with incidences of osteosarcoma observed in mice. Cumulative doses to the primitive hemopoietic stem cells, concentrated in the central marrow and thought to be susceptible to neoplastic transformation to myeloid leukemia, were considerably lower and also showed the trend plutonium > americium > uranium. PMID:10564934

Austin, A L; Ellender, M; Haines, J W; Harrison, J D; Lord, B I

1999-12-01

13

Streptavidin in antibody pretargeting. 5. chemical modification of recombinant streptavidin for labeling with the alpha-particle-emitting radionuclides 213Bi and 211At.  

PubMed

We are investigating the use of recombinant streptavidin (rSAv) as a carrier molecule for the short-lived alpha-particle-emitting radionuclides 213Bi ( t 1/2 = 45.6 min) and 211At ( t 1/2 = 7.21 h) in cancer therapy. To utilize rSAv as a carrier, it must be modified in a manner that permits rapid chelation or bonding with these short-lived radionuclides and also modified in a manner that diminishes its natural propensity for localization in the kidney. Modification for labeling with (213)Bi was accomplished by conjugation of rSAv with the DTPA derivative p-isothiocyanato-benzyl-CHX-A'' (CHX-A''), 3a. Modification for direct labeling with 211At was accomplished by conjugation of rSAv with an isothiocyanatophenyl derivative of a nido-carborane (nCB), 3b, or an isothiocyanatophenyl-dPEG/decaborate(2-) derivative, 3c. After conjugation of the chelating or bonding moiety, rSAv was further modified by reaction with an excess (50-100 equivalents) of succinic anhydride. Succinylation of the lysine amines has previously been shown to greatly diminish kidney localization. rSAv modified by conjugation with 3a and succinylated rapidly radiolabeled with 213Bi (<5 min), providing a 72% isolated yield. 211At labeling of modified rSAv was accomplished in aqueous solution using chloramine-T as the oxidant. Astatination of rSAv conjugated with 3b and succinylated occurred very rapidly (<1 min), providing a 50% isolated radiochemical yield. Astatination of rSAv conjugated with 3c and succinylated was also very rapid (<1 min) providing 66-71% isolated radiochemical yields. Astatination of succinylated rSAv, 2a, which did not have conjugated borane cage moieties, resulted in a much lower radiolabeling yield (18%). The 213Bi or 211At-labeled modified rSAv preparations were mixed with the corresponding 125 I-labeled rSAv, and dual-label in vivo distributions were obtained in athymic mice. The in vivo data show that 213Bi-labeled succinylated rSAv [ 213Bi] 6a has tissue concentrations similar to those of 125 I-labeled modified rSAv [ 125 I] 6b, suggesting that (213)Bi is quite stable toward release from the chelate in vivo. In vivo data also indicate that the (211)At-labeled rSAv conjugated with 3b or 3c and succinylated are stable to in vivo deastatination, whereas succinylated rSAv lacking a boron cage moiety is subject to some deastatination. The modified rSAv conjugated with nido-carborane derivative 3b has a higher retention in many tissues than rSAv without the carborane conjugated. Interestingly, the rSAv conjugated with 3c, which also contains an m-dPEG 12 moiety, has significantly decreased concentrations in blood and other tissues when compared with those of direct-labeled rSAv, suggesting that it may be a good candidate for further study. In conclusion, rSAv that has been modified with CHX-A'' and succinylated (i.e., 5a) may be useful as a carrier of 213Bi. The encouraging results obtained with the PEGylated decaborate(2-) derivative 3c and succinylated (i.e., 5c) suggests that its further study as a carrier of 211At in pretargeting protocols is warranted. PMID:18072725

Wilbur, D Scott; Hamlin, Donald K; Chyan, Ming-Kuan; Brechbiel, Martin W

2007-12-12

14

Engineered Modular Recombinant Transporters: Application of New Platform for Targeted Radiotherapeutic Agents to {alpha}-Particle Emitting {sup 211}At  

SciTech Connect

Purpose: To generate and evaluate a modular recombinant transporter (MRT) for targeting {sup 211}At to cancer cells overexpressing the epidermal growth factor receptor (EGFR). Methods and Materials: The MRT was produced with four functional modules: (1) human epidermal growth factor as the internalizable ligand, (2) the optimized nuclear localization sequence of simian vacuolating virus 40 (SV40) large T-antigen, (3) a translocation domain of diphtheria toxin as an endosomolytic module, and (4) the Escherichia coli hemoglobin-like protein (HMP) as a carrier module. MRT was labeled using N-succinimidyl 3-[{sup 211}At]astato-5-guanidinomethylbenzoate (SAGMB), its {sup 125}I analogue SGMIB, or with {sup 131}I using Iodogen. Binding, internalization, and clonogenic assays were performed with EGFR-expressing A431, D247 MG, and U87MG.wtEGFR human cancer cell lines. Results: The affinity of SGMIB-MRT binding to A431 cells, determined by Scatchard analysis, was 22 nM, comparable to that measured before labeling. The binding of SGMIB-MRT and its internalization by A431 cancer cells was 96% and 99% EGFR specific, respectively. Paired label assays demonstrated that compared with Iodogen-labeled MRT, SGMIB-MRT and SAGMB-MRT exhibited more than threefold greater peak levels and durations of intracellular retention of activity. SAGMB-MRT was 10-20 times more cytotoxic than [{sup 211}At]astatide for all three cell lines. Conclusion: The results of this study have demonstrated the initial proof of principle for the MRT approach for designing targeted {alpha}-particle emitting radiotherapeutic agents. The high cytotoxicity of SAGMB-MRT for cancer cells overexpressing EGFR suggests that this {sup 211}At-labeled conjugate has promise for the treatment of malignancies, such as glioma, which overexpress this receptor.

Rosenkranz, Andrey A. [Laboratory of Molecular Genetics of Intracellular Transport, Institute of Gene Biology, Russian Academy of Sciences, Moscow (Russian Federation); Department of Biophysics, Biological Faculty, Moscow State University, Moscow (Russian Federation); Vaidyanathan, Ganesan; Pozzi, Oscar R. [Department of Radiology, Duke University Medical Center, Durham, NC (United States); Lunin, Vladimir G. [Laboratory of Molecular Genetics of Intracellular Transport, Institute of Gene Biology, Russian Academy of Sciences, Moscow (Russian Federation); Gamaleya Institute of Epidemiology and Microbiology, Russian Academy of Medical Sciences, Moscow (Russian Federation); Zalutsky, Michael R. [Department of Radiology, Duke University Medical Center, Durham, NC (United States)], E-mail: zalut001@mc.duke.edu; Sobolev, Alexander S. [Laboratory of Molecular Genetics of Intracellular Transport, Institute of Gene Biology, Russian Academy of Sciences, Moscow (Russian Federation); Department of Biophysics, Biological Faculty, Moscow State University, Moscow (Russian Federation)], E-mail: sobolev@igb.ac.ru

2008-09-01

15

Nucleon-Alpha Particle Disequilibrium and Short-Lived r-Process Radioactivities  

NASA Astrophysics Data System (ADS)

r-Process yields can be extremely sensitive to expansion parameters when a persistent disequilibrium between free nucleons and alpha particles is present. This may provide a natural scenario for understanding the variation of heavy and light r-process isotopes in different r-process events.

Meyer, B. S.; Clayton, D. D.; Chellapilla, S.; The, L.-S.

2002-03-01

16

Cytotoxicity of ?-particle-emitting astatine-211-labelled antibody in tumour spheroids: no effect of hyperthermia  

Microsoft Academic Search

The high linear energy transfer, alpha-particle-emitting radionuclide astatine-211 (211At) is of interest for certain therapeutic applications; however, because of the 55- to 70-microm path length of its alpha-particles, achieving homogeneous tracer distribution is critical. Hyperthermia may enhance the therapeutic efficacy of alpha-particle endoradiotherapy if it can improve tracer distribution. In this study, we have investigated whether hyperthermia increased the cytotoxicity

ML Hauck; RH Larsen; PC Welsh

1998-01-01

17

Short-lived radioactivity and magma genesis  

NASA Astrophysics Data System (ADS)

Short-lived decay products of uranium and thorium have half-lives and chemistries sensitive to the processes and time scales of magma genesis, including partial melting in the mantle and magmatic differentiation in the crust. Radioactive disequilibrium between U-238, Th-230, and Ra-226 is widespread in volcanic rocks. These disequilibria and the isotopic composition of thorium depend especially on the extent and rate of melting as well as the presence and composition of vapor during melting. The duration of mantle melting may be several hundred millennia, whereas ascent times are a few decades to thousands of years. Differentiation of most magmas commonly occurs within a few millennia, but felsic ones can be tens of millennia old upon eruption.

Gill, James; Condomines, Michel

1992-09-01

18

Diffusion Experiment By Using The Short-Lived Radiotracer Of 8Li  

SciTech Connect

For an interdisciplinary application of the short-lived radioactive ion beams available at TRIAC, a non-destructive on-line radiotracer method for diffusion studies in solids has been developed. The experimental method using the {alpha}-emitting radioisotope of 8Li as the Li diffusion tracer in solids is introduced. The overview of the TRIAC, presently being operational for experiments, is briefly presented.

Jeong, S. C. [Institute of Panicle and Nuclear Studies, High Energy Accelerator Research Organization (KEK), Oho 1-1, Tsukuba, Ibaraki 305-0801 (Japan)

2006-11-02

19

Short-Lived Positron Emitter Labeled Radiotracers - Present Status.  

National Technical Information Service (NTIS)

The preparation of labelled compounds is important for the application of positron emission transaxial tomography (PETT) in biomedical sciences. This paper describes problems and progress in the synthesis of short-lived positron emitter ( exp 11 C, exp 18...

J. S. Fowler A. P. Wolf

1982-01-01

20

Beta and Gamma Spectra of Short-Lived Fission Products  

Microsoft Academic Search

Continuous spectra of beta particles and gamma rays emitted in the decay of short-lived fission products have been measured. These spectra, which cover the complete energy range available, can be used for checking results of detailed spectroscopic work on the decay of the nuclides studied. Another application of basic nature is the use of the beta spectra to evaluate the

G. Rudstam; P. I. Johansson; O. Tengblad; P. Aagaard; J. Eriksen

1990-01-01

21

Beta Decay Studies of Short Lived Barium Isotopes  

Microsoft Academic Search

The half-lives and relative intensities of several short lived neutron rich isotopes, with atomic numbers between 54 and 57, produced in the spontaneous fission of californium-252 were determined. This was accomplished from the study of the time variation of the K X-ray yields of these isotopes. A transport system which allowed us to study isotopes with half-lives less than 10

Charles Skipwith Bendall

1984-01-01

22

A Short-lived Metastable State in Titanium46  

Microsoft Academic Search

Benedetti and McGowan1, Mandeville and Scherb2 and Hirzel, Stoll and Wffler3 have attempted to detect short-lived metastable states of radioactive nuclei by using the method of delayed beta-beta and beta-gamma coincidences. Several decay periods have been detected by these methods. We have examined delayed gamma-gamma coincidences using a method similar to that used by Bunyan et al.4, but with two

B. D. Nag; Sunil Sen; Santimay Chatterjee

1949-01-01

23

Short-lived positron emitter labeled radiotracers - present status  

SciTech Connect

The preparation of labelled compounds is important for the application of positron emission transaxial tomography (PETT) in biomedical sciences. This paper describes problems and progress in the synthesis of short-lived positron emitter (/sup 11/C, /sup 18/F, /sup 13/N) labelled tracers for PETT. Synthesis of labelled sugars, amino acids, and neurotransmitter receptors (pimozide and spiroperidol tagged with /sup 11/C) is discussed in particular. (DLC)

Fowler, J.S.; Wolf, A.P.

1982-01-01

24

Injection of Short-Lived Isotopes into the Presolar Cloud  

NASA Astrophysics Data System (ADS)

The evidence for short-lived isotopes such as 26 Al and 41 Ca in meteorites requires their production either by irradiation in the solar nebula or by nucleosynthesis in a supernova or other evolved star. In the latter case, nucleosynthesis must be followed promptly by injection of the isotopes into the presolar cloud, a feat presumably accomplished by the same stellar outflow that transported the isotopes to the presolar cloud and possibly triggered its collapse. If their nucleosynthesis occurs deep within an unmixed star, the short-lived isotopes may lag far behind the leading edge of the stellar outflow, perhaps preventing their injection. However, we show that lagging isotopes can be injected into a collapsing protostar with an efficiency similar to that of material in the leading edge of the outflow, because fast-moving isotopes initially far behind (approximately a few parsecs) the leading edge impact and enter the cloud while the injection process is still underway. Isotope injection proceeds through Rayleigh-Taylor-like clumps in the shock-compressed target cloud.

Boss, Alan P.; Foster, Prudence N.

1998-02-01

25

Time-dependence in short-lived volcanic eruption plumes  

NASA Astrophysics Data System (ADS)

Establishing relationships between source conditions and plume evolution is critical for developing accurate, predictive models of volcanic plumes. Such relationships have been derived and successfully applied to field cases for long-duration eruptions with approximately constant source conditions. Similarly useful relationships exist for instantaneous releases. However, equivalent relationships have yet to be developed for time-varying and finite source conditions that drive many short-lived volcanic plumes, despite the fact that such eruptions are frequent in nature. Short-lived plumes have been observed and documented using UV, visible, and IR imaging techniques, as well as satellite and radar measurements. However, the source conditions which generate these plumes are difficult to constrain in the field. Thus, a laboratory investigation of jets and plumes generated by short-duration time-dependent sources was undertaken. Experiments were designed specifically to examine the role of time-dependent source conditions in controlling overall morphology, flow front velocity as a function of time, internal velocity and eddy structure, and entrainment characteristics. In the experimental work presented here, neutrally-buoyant turbulent jets were generated by injecting pressurized water into a tank of still water. Velocity and discharge rate with time were Gaussian-like with durations shorter than jet rise times. Flows had vent Reynolds numbers from 103 to 105 and were documented using flow visualization and particle image velocimetry. Two different flow patterns were observed: isolated vortex rings that separated from a trailing jet and head vortices connected to a trailing stem. The latter was favored as both the vent Reynolds number and the total ejected volume increased. These flows had three main phases of development - an injection phase which occurred while the source was 'on', a transition phase immediately following injection termination, and a final phase during which the flow continued to propagate although the injection had ended. The injection phase was further subdivided into two distinct sub-phases, corresponding to acceleration and deceleration at the vent. Scaling of the results indicate that individual characteristic velocities describe each of the acceleration, deceleration, and transition phases, whereas the final phase behaves like an instantaneous release of momentum, termed a puff. As such, time-dependent source conditions appear to have dominant first-order effects on flow evolution during the injection and transition phases but have little control over the dynamics during the final phase, when instead the total volume injected dominates the dynamics. These results have a number of implications for interpreting dynamics from observations of short-lived volcanic plumes. For example, estimates of vent fluxes from plume observations should be restricted to early 'source on' phases, while later stages of development should provide information about total volume erupted.

Chojnicki, K. N.; Clarke, A. B.; Phillips, J. C.; Adrian, R. J.

2011-12-01

26

Electron Scattering off Short-Lived Radioactive Nuclei  

NASA Astrophysics Data System (ADS)

We have established a novel method which make electron scattering off short-lived radioactive nuclei come into being. This novel method was named SCRIT (Self-Confining RI ion Target). It was based on the well known "ion trapping" phenomenon in electron storage rings. Stable nucleus, 133Cs, was used as target nucleus in the R&D experiment. The luminosity of interaction between stored electrons and Cs ions was about 1.02(0.06) 1026 cm-2s-1 at beam current around 80 mA. The angular distribution of elastically scattered electrons from trapped Cs ions was measured. And an online luminosity monitor was used to monitor the change of luminosity during the experiment.

Wang, S.; Emoto, T.; Furukawa, Y.; Ishii, K.; Ito, S.; Koseki, T.; Kurita, K.; Kuwajima, A.; Masuda, T.; Morikawa, A.; Nakamura, M.; Noda, A.; Ohnishi, T.; Shirai, T.; Suda, T.; Takeda, H.; Tamae, T.; Tongu, H.; Wakasugi, M.; Yano, Y.

27

Nondispersive x-ray diagnostics of short lived plasmas  

SciTech Connect

In this NATO Advanced Study Institute, we have discussed in detail the diagnosis of many pulse power machine properties, including their electrical behavior, grounding and shielding, and related data acquisition techniques. The purpose for many of these machines is to create high temperature/high density plasmas and, therefore, the subsequent behavior of these plasmas is of critical concern. The energy density of these plasmas is such that they will naturally radiate in the x-ray regime and thus the diagnosis of their x-ray emission is a crucial measurement of the entire system performance. In this lecture, I describe the general techniques used to perform nondispersive x-ray diagnostics of these short lived plasmas.

Day, R.H.

1983-01-01

28

Very short-lived Substances as Sources for Stratospheric Bromine  

NASA Astrophysics Data System (ADS)

Halogen-containing gases, when transported into the stratosphere, release chlorine and bromine atoms, which can lead to the destruction of ozone by catalytic cycles. Long-lived anthropogenic source gases like chlorofluorocarbons (CFCs), chlorocarbons, methyl bromide (CH3Br, also with natural sources) and halons are the most important sources for stratospheric halogen. While the budget of stratospheric chlorine is relatively well understood, greater uncertainties are present in terms of quantity and attribution of stratospheric bromine. BrO measurements in the stratosphere indicate abundances of inorganic bromine Bry that cannot be explained by the contribution from the long-lived halons and methyl bromide only. Additional input is expected to be provided by natural very-short-lived substances (VSLS), inorganic product gases and bromine tied to aerosols. We present measurements of all important brominated source gases, including the five most abundant VSLS, in the tropical tropopause layer (TTL) from balloon-borne air samples collected in June 2008 in Teresina (Brazil). The results were used to derive a local budget of organic bromine, which is revealing a considerable contribution from VSLS. We discuss variabilities in the concentrations of VSLS species both in the TTL and in the tropical marine boundary layer to assess the significance of our measurements on a global scale.

Brinckmann, Sven; Engel, Andreas; Bnisch, Harald

2010-05-01

29

Beta Decay Studies of Short Lived Barium Isotopes  

NASA Astrophysics Data System (ADS)

The half-lives and relative intensities of several short lived neutron rich isotopes, with atomic numbers between 54 and 57, produced in the spontaneous fission of californium-252 were determined. This was accomplished from the study of the time variation of the K X-ray yields of these isotopes. A transport system which allowed us to study isotopes with half-lives less than 10 seconds was developed. Mass assignments were made by comparing the experimental values of the half-lives with known values. A beta K X-ray coincidence technique was used to obtain the barium beta spectrum in coincidence with lanthanum K X -rays. A Kurie plot was performed on the spectrum to determine the beta groups. The probable origin of each beta group was determined through a comparison of the relative intensities of the isotopes and beta groups. Four beta groups probably from the decay of Ba-145 were revealed. The end point energies of these beta groups are 3870 (+OR-) 432 keV, 2772 (+OR-) 112 keV, 1894 (+OR-) 58 keV, and 746 (+OR-) 38 keV. The three lowest energy groups have not been observed before.

Bendall, Charles Skipwith

30

Counting Particles Emitted by Stratospheric Aircraft and Measuring Size of Particles Emitted by Stratospheric Aircraft. Final report, 1 May 1990-31 December 1992  

SciTech Connect

There were two principal objectives of the cooperative agreement between NASA and the University of Denver. The first goal was to modify the design of the ER-2 condensation nuclei counter (CNC) so that the effective lower detection limit would be improved at high altitudes. This improvement was sought because, in the instrument used prior to 1993, diffusion losses prevented the smallest detectable particles from reaching the detection volume of the instrument during operation at low pressure. Therefore, in spite of the sensor`s ability to detect particles as small as 0.008 microns in diameter, many of these particles were lost in transport to the sensing region and were not counted. Most of the particles emitted by aircraft are smaller than 0.1 micron in diameter. At the start date of this work, May 1990, continuous sizing techniques available on the ER-2 were only capable of detecting particles larger than 0.17 micron. Thus, the second objective of this work was to evaluate candidate sizing techniques in an effort to gain additional information concerning the size of particles emitted by aircraft.

Wilson, J.C.

1994-04-01

31

Morphology and chemistry of fine particles emitted from a Canadian coal-fired power plant  

Microsoft Academic Search

Particles emitted from coal-fired power plants burning subbituminous coal from Alberta, Canada were examined for total particulates (PM) and size fractions PM>10, PM10, and PM2.5. The sampling was carried out following EPA Method 201A. Three tests were performed at each station. The emitted particles were examined using SEM\\/EDX and gravimetric method for the determination of their sizes. The elemental composition

F. Goodarzi

2006-01-01

32

Harvard-MIT research program in short-lived radiopharmaceuticals. Final report.  

National Technical Information Service (NTIS)

The Harvard-MIT Research Program in Short-lived Radiopharmaceuticals was established in 1977 to foster interaction among groups working in radiopharmaceutical chemistry at Harvard Medical School, the Massachusetts Institute of Technology, and the Massachu...

S. J. Adelstein

1995-01-01

33

A Short-lived Lunar Magma Ocean. Implications for the Evolution of the Early Lunar Crust  

Microsoft Academic Search

Complexities in lunar sample geochemistry are not easily explained by the standard models for the evolution of the lunar crust. Evidence from W isotopes for a short-lived magma ocean could help in deciphering these complexities.

C. K. Shearer; H. E. Newsom

1999-01-01

34

Structural and fractal properties of particles emitted from spark ignition engines.  

PubMed

Size, morphology, and microstructure of particles emitted from one light-duty passenger vehicle (Buick Century; model year 1990; PM (particulate matter) mass emission rate 3.1 mg/km) and two light-duty trucks (Chevrolet C2; model year 1973; PM mass emission rate 282 mg/km, and Chevrolet El Camino; model year 1976; PM mass emission rate 31 mg/km), running California's unified driving cycles (UDC) on a chassis dynamometer, were studied using scanning electron microscopy (SEM). SEM images yielded particle properties including three-dimensional density fractal dimensions, monomer and agglomerate number size distributions, and three different shape descriptors, namely aspect ratio, root form factor, and roundness. The density fractal dimension of the particles was between 1.7 and 1.78, while the number size distribution of the particles placed the majority of the particles in the accumulation mode (0.1-0.3 microm). The shape descriptors were found to decrease with increasing particle size. Partial melting of particles, a rare and previously unreported phenomenon, was observed upon exposure of particles emitted during phase 2 of the UDC to the low accelerating voltage electron beam of the SEM. The rate of melting was quantified for individual particles, establishing a near linear relationship between the melting rate and the organic carbon 1 to elemental carbon ratio. PMID:17144291

Chakrabarty, Rajan K; Moosmller, Hans; Arnott, W Patrick; Garro, Mark A; Walker, John

2006-11-01

35

Production of short-lived positron sources for spin-polarized positron beams using a 35 MeV ?-beam  

NASA Astrophysics Data System (ADS)

Various short-lived positron sources for polarized positron beams have been on-line produced by irradiating nickel, aluminum, and silicon targets for the first time using a 35 MeV alpha beam from the RIKEN AVF cyclotron. The ?+ rays emitted from the targets with wide energy spread are converted to a monochromatic slow positron beam using a 10 ?m tungsten polycrystalline moderator. In the current stage, ~ 104 e+/(s ?A) can be obtained from nickel and aluminum targets, which is in relatively good agreement with the calculated slow positron yield. For silicon, a relatively low slow-positron intensity, ~ 103 e+/(s/?A) was obtained probably due to the charge up effect in the silicon surface during irradiation. For increasing the slow-positron yield loss of fast positrons in the material must be avoided, and as a new means for such improvement it is proposed to use gas targets.

Itoh, Yoshiko; Peng, Z. L.; Goto, Akira; Nakanishi, Noriyoshi; Kase, Masayuki; Lee, K. H.; Ito, Yasuo

1996-02-01

36

Characterization of particles emitted by incense burning in an experimental house.  

PubMed

The potential health effects of fine and ultrafine particles are of increasing concern. A better understanding of particle characteristics and dispersion behavior is needed. This study aims at characterizing spatial and temporal variations in fine and ultrafine particle dispersion after emission from a model source in an experimental house. Particles emitted by an incense stick burning for 15 min were characterized. Number concentration, specific surface area and mass were measured. Partial chemical analysis of particles was also realized. Near the burning incense stick, the maximum concentration was 25,500 particles/cm(3); the indoor PM(2.5) concentration reached 197 microg/m(3), and the specific surface area concentration was 180 microm(2)/cm(3). The estimated incense smoke density was 1.1 g/cm(3). Time of Flight Aerosol Mass Spectrometer measurements indicated that the organic fraction was predominant in the aerosol mass detected, and other minor components identified were K(+), NO(3)(-), and Cl(-). The combustion of an incense stick in the living room was associated with significant modifications of the concentrations of particles measured in the different rooms of the house. This demonstration of pollution by particle dispersion by a model source of moderate intensity may have significant implications in terms of assessment of indoor exposure to such particles. Practical Implications The particles emitted in a domestic environment by a source of moderate intensity such as burning incense disperse throughout the house, even in rooms with closed doors and in rooms as far away as the next floor. This dispersion has significant implications in terms of evaluating human indoor exposure to fine and ultrafine particles. PMID:20409193

Ji, X; Le Bihan, O; Ramalho, O; Mandin, C; D'Anna, B; Martinon, L; Nicolas, M; Bard, D; Pairon, J-C

2010-04-01

37

The evolution from birth to decay of a short-lived active region  

Microsoft Academic Search

In the following paper we present results of the analysis of NOAA active region 7968, which was the target of a coordinated observing campaign involving the instruments aboard the Solar and Heliospheric Observatory (SOHO), Yohkoh, and ground-based observatories (Bialkw, Pic du Midi, and Huairou). This active region was relatively short-lived, and thus provides a rare example of a region observed

Yuan Yong Deng; Brigitte Schmieder; Cristina H. Mandrini; Josef I. Khan; Pascal Dmoulin; Pawel Rudawy

1999-01-01

38

Release of short-lived fission products from intact and defected UO fuel elements  

Microsoft Academic Search

The rates of escape of short-lived isotopes of xenon and krypton to the coolant from a deliberately defected UO fuel element are at least 100 times greater than the release rates for identical species within an intact element. The enhanced escape is consistent with accelerated transport mechanisms under defect conditions. The rate of escape to the coolant of radioiodines is

Ian J. Hastings; C. E. Laurence Hunt; John J. Lipsett; Roderick D. MacDonald

1984-01-01

39

Synthesis of radiopharmaceuticals containing short-lived radionuclides. Progress report, March 1, 1985-February 26, 1986  

SciTech Connect

Methods for the rapid introduction of short-lived radionuclides into agents for use in diagnostic nuclear medicine are reported. Methods to synthesize radioiodinated fatty acids, lipids, and amphetamine derivatives are described. New routes for the introduction of bromine-77, chlorine-34m, and carbon-11 into agents of interest are elaborated. 46 refs.

Kabalka, G.W.

1985-09-01

40

Synthesis of radiopharmaceuticals containing short-lived radionuclides. Comprehensive report, March 1, 1980-February 26, 1986  

SciTech Connect

New methods for the rapid introduction of short-lived radionuclides into agents for use in diagnostic nuclear medicine are reported. Among the new syntheses reported are those for /sup 123/I-labeled fatty acids and steroids, for /sup 11/C-labeled alcohols, for /sup 13/N-labeled amines, and for /sup 15/O-labeled alcohols. 33 refs.

Kabalka, G.W.

1985-09-01

41

Diffusion Experiment By Using The Short-Lived Radiotracer Of 8Li  

NASA Astrophysics Data System (ADS)

For an interdisciplinary application of the short-lived radioactive ion beams available at TRIAC, a non-destructive on-line radiotracer method for diffusion studies in solids has been developed. The experimental method using the ?-emitting radioisotope of 8Li as the Li diffusion tracer in solids is introduced. The overview of the TRIAC, presently being operational for experiments, is briefly presented.

Jeong, S. C.

2006-11-01

42

On non-thermal nucleosynthesis of Short-Lived Radionuclei in the early solar system  

Microsoft Academic Search

The first results from the STARDUST mission revealed that refractory phases formed at a close distance from the nascent Sun have been transported to the comet forming region. Such refractory phases from meteorites (that originate from the asteroid belt), hold the ashes of Short-Lived Radionuclei (SLR) that were alive in the early solar system (ESS). We show that global energetic

Jean Duprat; Vincent Tatischeff

2008-01-01

43

Evidence for Short-Lived ^32Si in Presolar SiC grains of Type C  

NASA Astrophysics Data System (ADS)

Presolar SiC grains of type C have large ^29Si and ^30Si excesses as well as ^32S excesses. We propose that these ^32S excesses originate from the decay of short-lived ^32Si produced by high neutron densities (neutron burst) in core-collapse supernovae.

Zinner, E.; Hoppe, P.; Pignatari, M.

2013-09-01

44

A system for intercomparing standard solutions of beta-particle emitting radionuclides  

NASA Astrophysics Data System (ADS)

A system for intercomparing standard solutions of pure beta-particle emitting radionuclides is described. The CIEMAT/NIST technique of beta-particle efficiency tracing is based on establishing a parameter in a simple calculational model, using a 3H standard with comparable quenching. To produce a 3H-in-scintillator standard which is reasonably stable over the period of the measurements, we first standardized 3H-hexadecane solution by comparison with 3H-water standardized by gas counting. In the second phase of the work, the 3H-hexadecane solution was used to standardize 14C-hexadecane and 99Tc-tricaprylamine (TCA). Measurements were made under similar geometrical and quenching conditions for each radionuclide with a commercial scintillator and a conventional liquid-scintillation counter with two phototubes operating in coincidence. The technique was then tested at different sites in the area using a set of flame-sealed vials and state-of-the-art liquid-scintillation counters. Initial results for the 99Tc-TCA and the 1981 99Tc, Standard Reference Material (SRM) 4288 show an agreement to within 0.30%.

Calhoun, J. M.; Cessna, J. T.; Coursey, B. M.

1992-02-01

45

Determination of short-lived radionuclides in fresh fall-out debris for identification of nuclear weapon tests.  

PubMed

Radiochemical procedures for the assay of short-lived fission and activation products are described. They are rapid and quantitative and the radionuclides separated are radiochemically pure. Ratios of some of the short-lived radionuclides obtained by these measurements for selected Chinese and French nuclear tests are given and provide information about the fissile material used in the tests. PMID:18961860

Hingorani, S B; Khandekar, R N; Anand, S J

1976-04-01

46

Enhanced Retention of the ?-particle Emitting Daughters of Actinium-225 by Liposome Carriers  

PubMed Central

Targeted ?-particle emitters hold great promise as therapeutics for micrometastatic disease. Because of their high energy deposition and short range, tumor targeted ?-particles can result in high cancer-cell killing with minimal normal-tissue irradiation. Actinium-225 is a potential generator for ?-particle therapy: it decays with a 10-day half-life and generates three ?-particle emitting daughters. Retention of 225Ac daughters at the target increases efficacy; escape and distribution throughout the body increases toxicity. During circulation, molecular carriers conjugated to 225Ac cannot retain any of the daughters. We previously proposed liposomal encapsulation of 225Ac to retain the daughters, whose retention was shown to be liposome-size dependent. However, daughter retention was lower than expected: 22% of theoretical maximum decreasing to 14%, partially due to binding of 225Ac to the phospholipid membrane. In this study, MUltiVEsicular Liposomes (MUVELs) composed of different phospholipids were developed to increase daughter retention. MUVELs are large liposomes with entrapped smaller lipid-vesicles containing 225Ac. PEGylated MUVELs stably retained over time 98% of encapsulated 225Ac. Retention of 213Bi, the last daughter, was 31% of the theoretical maximum retention of 213Bi for the liposome sizes studied. MUVELs were conjugated to an anti-HER2/neu antibody (immunolabeled MUVELs), and were evaluated in vitro with SKOV3-NMP2 ovarian cancer cells, exhibiting significant cellular internalization (83%). This work demonstrates that immunolabeled MUVELs could be able to deliver higher fractions of generated ?-particles per targeted 225Ac compared to the relative fractions of ?-particles delivered by 225Ac-labeled molecular carriers.

Stavroula, Sofou; Kappel, Barry J.; Jaggi, Jaspreet S.; McDevitt, Michael R.; Scheinberg, David A.; Sgouros, George

2008-01-01

47

Streptavidin in Antibody Pretargeting. 5. Chemical Modification of Recombinant Streptavidin for Labeling with the ?-Particle Emitting Radionuclides 213Bi and 211At  

PubMed Central

We are investigating the use of recombinant streptavidin (rSAv) as a carrier molecule for the short-lived ?-particle emitting radionuclides 213Bi (t1/2 = 45.6 min) and 211At (t1/2 = 7.21 h) in cancer therapy. To utilize rSAv as a carrier, it must be modified in a manner that permits rapid chelation or bonding with these short-lived radionuclides, and also modified in a manner that diminishes its natural propensity for localization in kidney. Modification for labeling with 213Bi was accomplished by conjugation of rSAv with the DTPA derivative p-isothiocyanato-benzyl-CHX-A? (CHX-A?), 3a. Modification for direct labeling with 211At was accomplished by conjugation of rSAv with an isothiocyanatophenyl derivative of a nido-carborane (nCB), 3b, or an isothiocyanatophenyl-dPEG/decaborate(2-) derivative, 3c. After conjugation of the chelating or bonding moiety, rSAv was further modified by reaction with an excess (50100 equivalents) of succinic anhydride. Succinylation of the lysine amines has previously been shown to greatly diminish kidney localization. rSAv modified by conjugation with 3a and succinylated radiolabeled rapidly with 213Bi (< 5 min), providing a 72% isolated yield. 211At labeling of modified rSAv was accomplished in aqueous solution using chloramine-T as the oxidant. Astatination of rSAv conjugated with 3b and succinylated occurred very rapidly (<1 min), providing a 50% isolated radiochemical yield. Astatination of rSAv conjugated with 3c and succinylated was also very rapid (<1 min) providing 6671% isolated radiochemical yields. Astatination of succinylated rSAv, 2a, which did not have conjugated borane cage moieties, resulted in much lower radiolabeling yield (18%). The 213Bi- or 211At-labeled modified rSAv preparations were mixed with the corresponding 125I-labeled rSAv, and dual-label in vivo distributions were obtained in athymic mice. The in vivo data show that 213Bi-labeled succinylated rSAv [213Bi]6a has tissue concentrations similar to 125I-labeled modified rSAv [125I]6b, suggesting that 213Bi is quite stable towards release from the chelate in vivo. In vivo data also indicate that the 211At-labeled rSAv conjugated with 3b or 3c and succinylated are stable to in vivo deastatination, whereas succinylated rSAv lacking a boron cage moiety is subject to some deastatination. The modified rSAv conjugated with nido-carborane derivative 3b has a higher retention in many tissues than rSAv without the carborane conjugated. Interestingly, the rSAv conjugated with 3c, which also contains a m-dPEG12 moiety, has significantly decreased concentrations in blood and other tissues when compared with direct labeled rSAv, suggesting that it may be a good candidate for further study. In conclusion, rSAv that has been modified with CHX-A? and succinylated (i.e. 5a) may be useful as a carrier of 213Bi. The encouraging results obtained with the PEGylated decaborate(2-) derivative 3c and succinylated (i.e. 5c) suggests that its further study as a carrier of 211At in pretargeting protocols is warranted.

Wilbur, D. Scott; Hamlin, Donald K.; Chyan, Ming-Kuan; Brechbiel, Martin W.

2008-01-01

48

Radioimmunotherapy with alpha-emitting nuclides.  

PubMed

This review discusses the application of alpha particle-emitting radionuclides in targeted radioimmunotherapy. It will outline the production and chemistry of astatine-211, bismuth-212, lead-212, actinium-225, bismuth-213, fermium-255, radium-223 and terbium-149, which at present are the most promising alpha-emitting isotopes available for human clinical use. The selective cytotoxicity offered by alpha particle-emitting radioimmunoconstructs is due to the high linear energy transfer and short particle path length of these radionuclides. Based upon the pharmacokinetics of alpha particle-emitting radioimmunoconstructs, both stochastic and conventional dosimetric methodology is discussed, as is the preclinical and initial clinical use of these radionuclides conjugated to monoclonal antibodies for the treatment of human neoplasia. PMID:9724387

McDevitt, M R; Sgouros, G; Finn, R D; Humm, J L; Jurcic, J G; Larson, S M; Scheinberg, D A

1998-09-01

49

Efficient adsorption of waterborne short-lived radon decay products by glass fiber filters.  

PubMed

Glass fiber filters of a certain brand were found to be very efficient (retention > 95%) for adsorption of short-lived radon decay products during filtration of water. Carrier-free samples are obtained in a convenient geometry for efficient gross beta counting. Adsorption of "hot atoms" is not disturbed by the presence of "cold" lead ions. Approximate radioactive equilibrium between radon and its short-lived decay products may or may not exist in water at the source, but does exist after 3 h in PET bottles. These bottles are shown to be gas-tight for radon. Calibration of activity concentration in Bq L(-1) (radon gas concentration approximately equilibrium equivalent radon concentration) was performed by several standard procedures. Limit of detection is 2 Bq L(-1) within 10 min (total time) or 10 Bq L(-1) within 5 min for a net signal of 5 times standard deviation. PMID:9003713

von Philipsborn, H

1997-02-01

50

Experimental Measurements of Short-Lived Fission Products from Uranium, Neptunium, Plutonium and Americium  

SciTech Connect

Fission yields are especially well characterized for long-lived fission products. Modeling techniques incorporate numerous assumptions and can be used to deduce information about the distribution of short-lived fission products. This work is an attempt to gather experimental (model-independent) data on the short-lived fission products. Fissile isotopes of uranium, neptunium, plutonium and americium were irradiated under pulse conditions at the Washington State University 1 MW TRIGA reactor to achieve ~108 fissions. The samples were placed on a HPGe (high purity germanium) detector to begin counting in less than 3 minutes post irradiation. The samples were counted for various time intervals ranging from 5 minutes to 1 hour. The data was then analyzed to determine which radionuclides could be quantified and compared to the published fission yield data.

Metz, Lori A.; Payne, Rosara F.; Friese, Judah I.; Greenwood, Lawrence R.; Kephart, Jeremy D.; Pierson, Bruce D.

2009-11-01

51

CHARACTERIZATION OF SHORT-LIVED INTERMEDIATES PRODUCED DURING REPLICATION OF BACULOVIRUS DNA  

PubMed Central

SUMMARY In this report the short-lived DNA replication intermediates produced in both uninfected and Autographa californica multiple nucleopolyhedrovirus (AcMNPV) infected Spodoptera frugiperda cells were characterized. The methods used included pulse-labeling of DNA in permiabilized cells, treatment of nascent DNA with Mung bean nuclease, and electrophoresis in neutral and alkaline agarose gels. In contrast to uninfected cells that produced a population of small DNA fragments of about 200 bp, a population of heterogeneous fragments of up to 5 kb with an average size of 1 to 2 kb derived randomly from the virus genome was identified as the short-lived intermediates produced during AcMNPV replication. The intermediates likely include Okazaki fragments derived from the lagging strands in viral replication forks as well as fragments produced during the recombination-dependent replication.

Mikhailov, Victor S.; Rohrmann, George F.

2009-01-01

52

Dose and dose rate effects of beta-particle emitting radioactive stents in a porcine model of restenosis  

Microsoft Academic Search

Background. Radioactive stents have been proposed as a means to prevent in-stent restenosis by inhibiting intimal proliferation with continuous low-dose irradiation.Objectives. The purpose of this study is to determine the effects of cumulative dose and dose-rate delivery on neointimal formation using 32P and 90Y beta-particle emitting radioactive stents in a porcine coronary model of restenosis.Methods and Materials. We compared the

Andrew J. Carter; Stephen Jenkins; William Sweet; Lynn Bailey; Russ Jones; Tim A. Fischell; Renu Virmani

1999-01-01

53

STUDIES OF SHORT-LIVED FISSION PRODUCTS AND THEIR IMPORTANCE TO REACTOR TECHNOLOGY  

Microsoft Academic Search

A systematic study of the decay schemes of some of the important alkali ; metal isotopes was made. Information is available on 17.8-minute Rb⁸⁸, ; 14.9-minute Rb⁸⁹, and 2.6-minute Rb⁹°. The decay characteristics of ; these nuclides show the general features exhibited by all of the short-lived ; fission products studied so far, namely, the short half-lives are related to

G. D. OKelley; E. Eichler; N. R. Johnson

1958-01-01

54

Heavy-ion-induced production and physical preseparation of short-lived isotopes for chemistry experiments  

Microsoft Academic Search

Physical separation of short-lived isotopes produced in heavy-ion-induced fusion reactions is a powerful and well-known method and often applied in investigations of the heaviest elements, called the transactinides (Z?104). By extracting these isotopes from a recoil separator, they can be made available for transport to setups located outside the heavily shielded irradiation position such as chemistry setups. This physical preseparation

Ch. E. Dllmann; C FOLDENIII; K. E. Gregorich; D. C. Hoffman; D. Leitner; G. K. Pang; R. Sudowe; P. M. Zielinski; H. Nitsche

2005-01-01

55

Simulation Studies of Diffusion-Release and Effusive Flow of Short-Lived Radioactive Isotopes  

Microsoft Academic Search

Simulation studies with computer models offer cost effective methods for designing targets and vapor transport systems at Isotope Separator On-Line (ISOL)-based radioactive ion beam facilities. A finite difference code, Diffuse II, was developed at the Oak Ridge National Laboratory (ORNL) for studying diffusion-release of short-lived ion species from the three principal target geometries; results derived by use of the code

Y. Zhang; G. D. Alton; Y. Kawai

2005-01-01

56

Multimodel projections of climate change from short-lived emissions due to human activities  

Microsoft Academic Search

We use the GISS (Goddard Institute for Space Studies), GFDL (Geophysical Fluid Dynamics Laboratory) and NCAR (National Center for Atmospheric Research) climate models to study the climate impact of the future evolution of short-lived radiatively active species (ozone and aerosols). The models used mid-range A1B emission scenarios, independently calculated the resulting composition change, and then performed transient simulations to 2050

Drew T. Shindell; Hiram Levy; M. Daniel Schwarzkopf; Larry W. Horowitz; Jean-Francois Lamarque; Greg Faluvegi

2008-01-01

57

Efficient adsorption of waterborne short-lived radon decay products by glass fiber filters  

Microsoft Academic Search

Glass fiber filters of a certain brand were found to be very efficient (retention > 95%) for adsorption of short-lived radon decay products during filtration of water. Carrier-free samples are obtained in a convenient geometry for efficient gross beta counting. Adsorption of {open_quotes}hot atoms{close_quotes} is not disturbed by the presence of {open_quotes}cold{close_quotes} lead ions. Approximate radioactive equilibrium between radon and

H. Von Philipsborn; H. von

1997-01-01

58

Resprouting after disturbance: an experimental study with short-lived monocarpic herbs  

Microsoft Academic Search

We experimentally demonstrated the ability of three short-lived monocarpic species to vegetatively regenerate (resprout) from\\u000a roots after severe disturbance. We assessed the relationship between resprouting ability and (1) timing of injury with respect\\u000a to life-cycle stage (reproductive vs. vegetative plant), life-history mode (annual vs. winter annual) and phenological stage\\u000a (flowering vs. fruiting plant), (2) nutrient availability, and (3) disturbance severity

Jana Martnkov; Jitka Klimeov; Stanislav Mihulka

2004-01-01

59

Storm time, short-lived bursts of relativistic electron precipitation detected by subionospheric radio wave propagation  

Microsoft Academic Search

In this study we report on ground-based observations of short bursts of relativistic electron precipitation (REP), detected by a subionospheric propagation sensor in Sodankyl, Finland during 2005. In two ~4 hour case study periods from L = 5.2, around local midnight, several hundred short-lived radio wave perturbations were observed, covering a wide range of arrival azimuths. The vast majority (~99%)

Craig J. Rodger; Mark A. Clilverd; David Nunn; Pekka T. Verronen; Jacob Bortnik; Esa Turunen

2007-01-01

60

Radioimmunotherapy with alpha-emitting nuclides  

Microsoft Academic Search

. This review discusses the application of alpha particle-emitting radionuclides in targeted radioimmunotherapy. It will outline\\u000a the production and chemistry of astatine-211, bismuth-212, lead-212, actinium-225, bismuth-213, fermium-255, radium-223 and\\u000a terbium-149, which at present are the most promising alpha-emitting isotopes available for human clinical use. The selective\\u000a cytotoxicity offered by alpha particle-emitting radioimmunoconstructs is due to the high linear energy transfer

Michael R. McDevitt; George Sgouros; Ronald D. Finn; John L. Humm; Joseph G. Jurcic; Steven M. Larson; David A. Scheinberg

1998-01-01

61

Results from the first national UK inter-laboratory calibration for very short-lived halocarbons  

NASA Astrophysics Data System (ADS)

Very short-lived halocarbons (VSLH) such as CH3I, CH2Br2 and CHBr3 provide an important source of reactive halogens to the atmosphere, however high spatial and seasonal variability in their ambient mixing ratios and sea-air fluxes gives rise to considerable uncertainty in global scale emission estimates. One solution to improve global flux estimates is to combine the multitude of individually published datasets to produce a database of collated global halocarbon observations. Some progress towards this has already been achieved through the HalOcAt (Halocarbons in the Ocean and Atmosphere) database initiative, but the absence of a common calibration scale for very short-lived halocarbons makes it difficult to distinguish true environmental variations from artefacts arising from differences between calibration methodologies. As such, the lack of inter-calibrations for both air and seawater measurements of very short-lived halocarbons has been identified as a major limitation to current estimations of the global scale impact of these reactive trace gases. Here we present the key findings from the first national UK inter-laboratory comparison for calibrations of the halocarbons CH3I, CH2Br2 and CHBr3. The aim of this inter-calibration was to provide transparency between halocarbon calibrations from major UK research institutions, an important step towards enabling all measurements from these institutions to be treated as one coherent integrated dataset for global source term parameterisations.

Jones, C. E.; Andrews, S. J.; Carpenter, L. J.; Hogan, C.; Hopkins, F. E.; Laube, J. C.; Robinson, A. D.; Spain, T. G.; Archer, S. D.; Harris, N. R. P.; Nightingale, P. D.; O'Doherty, S. J.; Oram, D. E.; Pyle, J. A.; Butler, J. H.; Hall, B. D.

2011-05-01

62

Results from the first national UK inter-laboratory calibration for very short-lived halocarbons  

NASA Astrophysics Data System (ADS)

Very short-lived halocarbons (VSLH) such as CH3I, CH2Br2 and CHBr3 provide an important source of reactive halogens to the atmosphere, however high spatial and seasonal variability in their ambient mixing ratios and sea-air fluxes gives rise to considerable uncertainty in global scale emission estimates. One solution to improve global flux estimates is to combine the multitude of individually published datasets to produce a database of collated global halocarbon observations. Some progress towards this has already been achieved through the HalOcAt (Halocarbons in the Ocean and Atmosphere) database initiative, however the absence of a common calibration scale for very short-lived halocarbons makes it difficult to distinguish true environmental variations from artefacts arising from differences between calibration methodologies. As such, the lack of inter-calibrations for both air and seawater measurements of very short-lived halocarbons has been identified as a major limitation to current estimations of the global scale impact of these reactive trace gases. Here we present the key findings from the first national UK inter-laboratory comparison for calibrations of the halocarbons CH3I, CH2Br2 and CHBr3. The aim of this inter-calibration was to provide transparency between halocarbon calibrations from major UK research institutions, an important step towards enabling all measurements from these institutions to be treated as one coherent integrated dataset for global source term parameterisations.

Jones, C. E.; Andrews, S. J.; Carpenter, L. J.; Hogan, C.; Hopkins, F. E.; Laube, J. C.; Robinson, A. D.; Spain, T. G.; Archer, S. D.; Harris, N. R. P.; Nightingale, P. D.; O'Doherty, S. J.; Oram, D. E.; Pyle, J. A.; Butler, J. H.; Hall, B. D.

2011-01-01

63

Analyses of new short-lived replacements for HFCs with large GWPs  

NASA Astrophysics Data System (ADS)

this study, we examine the atmospheric lifetimes and Global Warming Potentials (GWPs) for six short-lived potential ozone-depleting substances and high-GWP hydrofluorocarbons (HFCs) replacement compounds and evaluate the potential reduced effects on climate forcing from adopting such compounds. We also examine the potential effects on climate from widespread use of these chemicals. The atmospheric lifetimes of these compounds are each less than 1 month and their 100 year GWPs range from 0.9 to 4.6. The derived GWPs are substantially lower than those in prior published studies, which used simplified estimation techniques that overestimate the GWPs for these short-lived compounds by 61% to 237%. If long-lived HFCs are completely replaced with these substitute compounds, radiative forcing of these short-lived compounds in 2050 will be 0.26 to 0.80 mW m-2, a factor of as much as 1000 smaller than would be the case with the potential growth in the use of the HFCs.

Wuebbles, Donald J.; Wang, Dong; Patten, Kenneth O.; Olsen, Seth C.

2013-09-01

64

Detection and localization of particle-emitting sources with compound-eye inspired detector arrays  

NASA Astrophysics Data System (ADS)

We develop methods to detect and localize particle-emitting sources using detector arrays that are inspired by biological compound eyes. The sources of interest may be optical, nuclear, or cosmic; they emit particles such as visible photons, neutrons, protons, or charged particles. Our results may have wide applications to artificial vision, which can be important in robotics (robot vision) or medicine (e.g., artificial eyes for the blind); security, where the detection of nuclear materials is needed; or astronomy. This dissertation consists of three parts. First, we detect a far-field particle source using two directional detector arrays: cubic and spherical. We propose a mean-difference test (MDT) detector, analyze its statistical performance, and show that the MDT has a number of advantages over the generalized likelihood- ratio test (GLRT). Second, we localize the source by proposing a novel biologically inspired detector array, whose configuration generalizes the compound eye of insects. This array combines the advantages of compound eyes (e.g., large field-of-view) and human eyes (e.g., high angular resolution). Based on a statistical model of the array measurements, we analyze the array performance by computing the Cramrao bound (CRB) on the error in estimating the source direction. We also derive lower bounds on the mean-square angular error (MSAE) of the source localization and investigate the MSAE of two source- direction estimators. Numerical examples, including the optimal array design, are presented to further illustrate the array performance. Third, we derive a statistical angular resolution limit (ARL) on resolving two closely spaced point sources in a three-dimensional frame, which is applicable to various measurement models (e.g., radar, sonar, or astronomy). Using the asymptotic analysis of the GLRT, we derive the ARL with constraints on the probabilities of false alarm and detection. Our results give explicit analytical expression for the ARL that is proportional to the square root of the CRB on the angular source separation, or equivalently to the lower bound on the MSAE.

Liu, Zhi

2007-08-01

65

The Developing Role of Short-Lived Radionuclides in Nuclear Medicine. A Report of the Task Force on Short-Lived Radionuclides for Medical Applications to the BRH, FDA.  

National Technical Information Service (NTIS)

The report recommends support of research in the methods of production, distribution, biomedical application and cost effectiveness of a number of accelerator produced and short-lived radionuclides by agencies of the Federal Government. These nuclides, al...

1977-01-01

66

Health co-benefits of mitigating short-lived climate forcers  

NASA Astrophysics Data System (ADS)

Tropospheric ozone and black carbon (BC), a component of fine particulate matter (PM2.5), are associated with premature mortality and disrupt global and regional climate. While attention to their impacts on climate is relatively new, these pollutants have been regulated under health-based standards in the US and elsewhere in the world for decades. Understanding the health benefits of reducing short-lived climate forcers may help inform mitigation strategies, since health will likely continue to drive concern over air quality in the future. Several recent studies have examined the health and climate co-benefits of control measures targeting BC and methane, an ozone precursor. This talk will highlight the health benefits of 14 presently available BC and methane mitigation measures examined in the United Nations Environment Programme/World Meteorological Organization Integrated Assessment of Black Carbon and Ozone. Fully implementing these specific measures is estimated to avoid 1-5 million annual ozone and PM2.5-related premature deaths globally in 2030, >80% of which occur in Asia. BC mitigation measures are estimated to achieve ~98% of the avoided deaths from all measures, due to associated reductions of non-methane ozone precursor and organic carbon emissions and stronger mortality relationships for PM2.5 relative to ozone. These substantial public health co-benefits of mitigating short-lived climate forcers are independent of whether CO2 measures are enacted. Further analyses are needed to improve economic valuation of the varied impacts of short-lived climate forcers and quantify the benefits and costs of these measures in individual countries or regions to support policy decisions made at the national level.

Anenberg, S.

2011-12-01

67

Phase-Imaging Ion-Cyclotron-Resonance Measurements for Short-Lived Nuclides  

NASA Astrophysics Data System (ADS)

A novel approach based on the projection of the Penning-trap ion motion onto a position-sensitive detector opens the door to very accurate mass measurements on the ppb level even for short-lived nuclides with half-lives well below a second. In addition to the accuracy boost, the new method provides a superior resolving power by which low-lying isomeric states with excitation energy on the 10-keV level can be easily separated from the ground state. A measurement of the mass difference of Xe130 and Xe129 has demonstrated the great potential of the new approach.

Eliseev, S.; Blaum, K.; Block, M.; Droese, C.; Goncharov, M.; Minaya Ramirez, E.; Nesterenko, D. A.; Novikov, Yu. N.; Schweikhard, L.

2013-02-01

68

Properties of short-living ball lightning produced in the laboratory  

NASA Astrophysics Data System (ADS)

An experimental setup for highly reproducible generation of artificial ball lightnings is implemented. Thousands of floating glowing plasmoids 12-20 cm in diameter are produced. Research facilities for studying the plasmoids are developed. It is found that short-lived ball lightnings live for about 1 s and carry an electric charge. The lightnings are shown to have a complex structure: a central kernel containing a rich variety of hydrated ions and aerosol of decay products is surrounded by a thin negatively charged shell.

Egorov, A. I.; Stepanov, S. I.

2008-06-01

69

Laser generation of proton beams for the production of short-lived positron emitting radioisotopes  

NASA Astrophysics Data System (ADS)

Protons of energies up to 37 MeV have been generated when ultra-intense lasers (up to 1020Wcm-2) interact with hydrogen containing solid targets. These protons can be used to induce nuclear reactions in secondary targets to produce ?+-emitting nuclei of relevance to the nuclear medicine community, namely 11C and 13N via (p,n) and /(p,?) reactions. Activities of the order of 200 kBq have been measured from a single laser pulse interacting with a thin solid target. The possibility of using ultra-intense lasers to produce commercial amounts of short-lived positron emitting sources for positron emission tomography (PET) is discussed.

Spencer, I.; Ledingham, K. W. D.; Singhal, R. P.; McCanny, T.; McKenna, P.; Clark, E. L.; Krushelnick, K.; Zepf, M.; Beg, F. N.; Tatarakis, M.; Dangor, A. E.; Norreys, P. A.; Clarke, R. J.; Allott, R. M.; Ross, I. N.

2001-10-01

70

Coupling a Knudsen reactor with the short lived radioactive tracer 13N for atmospheric chemistry studies  

NASA Astrophysics Data System (ADS)

A Knudsen cell flow reactor was coupled to an online gas phase source of the short-lived radioactive tracer 13N to study the adsorption of nitrogen oxides on ice at temperatures relevant for the upper troposphere. This novel approach has several benefits over the conventional coupling of a Knudsen cell with a mass spectrometer. Experiments at lower partial pressures close to atmospheric conditions are possible. The uptake to the substrate is a direct observable of the experiment. Operation of the experiment in continuous or pulse mode allows to retrieve steady state uptake kinetics and more details of adsorption and desorption kinetics.

Schreiber, S.; Kerbrat, M.; Huthwelker, T.; Birrer, M.; Ammann, M.

2013-03-01

71

Search for a short-lived neutral particle produced in nuclear decay  

Microsoft Academic Search

We report on a search for a short-lived neutral particle phi produced in the decay of the 9.17-MeV J-italic\\/sup ..pi..\\/ = 2\\/sup +\\/ state in ¹⁴N. The experiment is sensitive to decays into an e-italic\\/sup +\\/e⁻ pair with tau\\/sub phi\\/approx. <10⁻¹¹ s. For m-italic\\/sub phi\\/ = 1.7 MeV we place a limit on the branching ratio of GAMMA\\/sub phi\\/\\/GAMMA\\/sub ..gamma..\\/<

M. J. Savage; R. D. McKeown; B. W. Filippone; L. W. Mitchell

1986-01-01

72

Accurate mass determination of short-lived isotopes by a tandem Penning-trap mass spectrometer  

SciTech Connect

A mass spectrometer consisting of two Penning traps has been set up for short-lived isotopes at the on-line mass separator ISOLDE at CERN. The ion beam is collected and cooled in the first trap. After delivery to the second trap, high-accuracy direct mass measurements are made by determining the cyclotron frequency of the stored ions. Measurements have been performed for {sup 118}Cs--{sup 137}Cs. A resolving power of over 10{sup 6} and an accuracy of 1.4{times}10{sup {minus}7} have been achieved, corresponding to about 20 keV.

Stolzenberg, H.; Becker, S.; Bollen, G.; Kern, F.; Kluge, H.; Otto, T.; Savard, G.; Schweikhard, L. (Institut fuer Physik, Universitaet Mainz, D-6500 Mainz (Federal Republic of Germany)); Audi, G. (Centre de Spectrometrie Nucleaire et de Spectrometrie de Masse, Laboratoire Rene Bernas, Batiment 108, F-91405 Orsay (France)); Moore, R.B. (Foster Radiation Laboratory, McGill University, Montreal (Canada)); The ISOLDE Collaboration

1990-12-17

73

Compton suppression spectrometry for analysis of short-lived neutron activation products in foods  

Microsoft Academic Search

Compton suppression spectrometry was used to analyze foods for elements with short-lived neutron activation products (half-lives\\u000a of about 2 minutes to 1.5 days). Analysis conditions were optimized to provide quality assurance analyses for iodine in FDAs\\u000a Total Diet Study. Iodine mass fractions (0.075 to 2.03 mg\\/kg) were measured in 19 of 42 foods analyzed, with limits of detection\\u000a (LODs) ranging

D. L. Anderson; W. C. Cunningham

2008-01-01

74

Short-lived Absorptive Type III-like Microwave Bursts as a Signature of Fragmented Electron Injections  

Microsoft Academic Search

In this paper, we devote ourselves to interpreting the short-lived absorptive type III-like microwave bursts in the 2006 December 13 flare event observed with high temporal and spectral resolutions (8 ms and 10 MHz) by the Chinese Solar Broadband Radio Spectrometer (SBRS\\/Huairou) at 2.6-3.8 GHz. In the decimeter-centimeter wavelength range, we first present the observations of short-lived bursts represented as

Bin Chen; Yihua Yan

2008-01-01

75

Utilization of a boron irradiation vessel for NAA of short-lived radionuclides in biological and geological materials  

Microsoft Academic Search

A boron nitride irradiation vessel designed for use with a pneumatic tube transfer system has been used to analyze short-lived radionuclides by NAA. Bare and Cd-shielded irradiations on Co, Zr and Au were made to characterize the neutron fluxes in the irradiation position. Bare and BN-shielded irradiations were performed to determine epithermal advantage factors for 16 short-lived reactions and interference

M. D. Glascock; W. Z. Than; W. D. Ehmann

1985-01-01

76

Infection resistance of surface modified catheters with either short-lived or prolonged activity.  

PubMed

It has been suggested that the invasion of microbes into the catheter tract occurs mainly at the time of catheter insertion. To investigate whether the presence of an antimicrobial environment during the initial period after insertion is sufficient to reduce the risk of subsequent catheter colonization and infection, we evaluated the use of benzalkonium chloride-heparin bonded (BZK-hep) central venous catheters, which exhibit short-lived surface antimicrobial activity, using a rat subcutaneous model. Bacterial adherence on these catheters was determined, seven days after challenging the insertion site with 10(6) cfu of Staphylococcus aureus. A chlorhexidine-silver sulphadiazine impregnated catheter (Arrowg+ard), with longer lasting surface antimicrobial activity, and a hydrophilic coated catheter ('Hydrocath'), were evaluated simultaneously for comparison. Unlike Arrowg+ard antiseptic catheters, BZK-hep 'Hydrocath' and control catheters had significant bacterial adherence on their surface. Arrowg+ard catheters were colonized in 19% of the animals compared with 100% in all the other groups (P < 0.05; mean cfu cm-2: control = 1.3 x 10(6), BZK-hep = 4.3 x 10(5), Hydrocath = 2 x 10(5), Arrowg+ard = 71). Our results indicate that catheters with short-lived surface antimicrobial activity are unlikely to provide long-term protection against catheter-related infection. The efficacy of Arrowg+ard catheters may be due to the initial high rate of kill and prolonged antimicrobial activity. PMID:8522776

Sampath, L A; Chowdhury, N; Caraos, L; Modak, S M

1995-07-01

77

Latest Olduvai short-lived reversal episodes recorded in Chinese loess  

NASA Astrophysics Data System (ADS)

A duplicate high-resolution magnetic record was obtained from two parallel loess sections separated by about 300 m near Baoji city, southern Chinese Loess Plateau. This reveals at least eight short-lived reversed polarity episodes in the uppermost part of the Olduvai normal polarity subchronozone. Rock magnetic experiments and anisotropy of low-field magnetic susceptibility confirm that the multiple occurrence of short-lived reversals is not due to rock-magnetic and/or sedimentary causes. Assuming a constant accumulation rate within the Olduvai subchron, the short episode zone was estimated to span about 24-30 ka and 24-31 ka for the two sections, respectively. The duration of each short episode ranges from about 0.3 ka to 2.1 ka. The present results together with previous worldwide observations show that the occurrence of numerous short reversals is peculiar to the latest Olduvai subchron. The geodynamo may have been in an anomalous state at that time.

Yang, Tianshui; Hyodo, Masayuki; Yang, Zhenyu; Ding, Lin; Li, Huidi; Fu, Jianli; Wang, Shubing; Wang, Hongwei; Mishima, Toshiaki

2008-05-01

78

Short-lived pollutants in the Arctic: their climate impact and possible mitigation strategies  

SciTech Connect

Several short-lived pollutants known to impact Arctic climate may be contributing to the accelerated rates of warming observed in this region relative to the global annually averaged temperature increase. Here, we present a summary of the short-lived pollutants that impact Arctic climate including methane, tropospheric ozone, and tropospheric aerosols. For each pollutant, we provide a description of the major sources and the mechanism of forcing. We also provide the first seasonally averaged forcing and corresponding temperature response estimates focused specifically on the Arctic. The calculations indicate that the forcings due to black carbon, methane, and tropospheric ozone lead to a positive surface temperature response indicating the need to reduce emissions of these species within and outside the Arctic. Additional aerosol species may also lead to surface warming if the aerosol is coincident with thin, low lying clouds. We suggest strategies for reducing the warming based on current knowledge and discuss directions for future research to address the large remaining uncertainties.

Menon, Surabi; Quinn, P.K.; Bates, T.S.; Baum, E.; Doubleday, N.; Fiore, A.M.; Flanner, M.; Fridlind, A.; Garrett, T.J.; Koch, D.; Menon, S.; Shindell, D.; Stohl, A.; Warren, S.G.

2007-09-24

79

Efficient adsorption of waterborne short-lived radon decay products by glass fiber filters  

SciTech Connect

Glass fiber filters of a certain brand were found to be very efficient (retention > 95%) for adsorption of short-lived radon decay products during filtration of water. Carrier-free samples are obtained in a convenient geometry for efficient gross beta counting. Adsorption of {open_quotes}hot atoms{close_quotes} is not disturbed by the presence of {open_quotes}cold{close_quotes} lead ions. Approximate radioactive equilibrium between radon and its short-lived decay products may or may not exist in water at the source, but does exist after 3 b in PET bottles. These bottles are shown to be gas-tight for radon. Calibration of activity concentration in Bq L{sup -1} (radon gas concentration - equilibrium equivalent radon concentration) was performed by several standard procedures. Limit of detection is 2 Bq L{sup - 1} within 10 min (total time) or 10 Bq L{sup -1} within 5 min for a net signal of 5 times standard deviation. 13 refs., 5 figs.

Philipsborn, H. von [Univ. of Regensburg (Germany)

1997-02-01

80

Short-lived organic trace gases in the UT/LS: Results from recent field campaigns.  

NASA Astrophysics Data System (ADS)

The chemistry of the upper troposphere/lower stratosphere can be impacted by delivery of reactive trace gases that are variable in composition and depend on source emissions and transport pathway and time. Because surface emissions include gases with a range of chemical lifetimes, and because different source emissions (e.g. marine boundary layer, anthropogenic emissions, biomass burning) can have different chemical signatures, the composition of the organic trace gases that are found in the UT/LS region have the potential to provide diagnostic information on air mass sources and transport time scales. Further, the role of short-lived organic halogen gases in the UT/LS has been highlighted as a major uncertainty for defining the reactive halogen budget and the chemical boundary conditions for the stratospheric chemistry that affects ozone depletion rates. Recent campaigns in the tropics (TC-4 and AVE missions) and in the extra-tropics (START08) have included the measurement of trace gases from whole air sampling and analysis on the NASA WB-57 or NSF Gulfstream V aircraft. Measurements of a range of halocarbons, hydrocarbons, organic nitrates, and sulfur species were made to examine the role of short-lived organic gases in the UT/LS. This presentation will highlight different aspects of these measurements that deal with transport pathways, transport rates, and halogen budgets.

Atlas, E.; Lueb, R.; Zhu, X.; Pope, L.; Schauffler, S.; Pan, L.; Bowman, K. P.; Blake, D.; Meinardi, S.

2008-12-01

81

Activities Study of Short-lived Radioisotopes with a Filippov-type Plasma Focus  

NASA Astrophysics Data System (ADS)

Plasma focus devices are characterized by short-lived dense and hot plasma "pinch" due to the radial compression and electromagnetic acceleration. Through a short period of time, typically a few tens of nanoseconds, the pinched plasma goes through two phases of compression (thermal) and expansion (non-thermal or beam target) that provide necessary conditions for high nuclear reaction rates. If appropriate gas admixture at a desirable pressure is used, the processes can generate short-lived radioisotopes (SLRs) which the level of activities depends on the design and operational parameters. In this paper, the results of simulated theoretical works of two SLRs such as 10B (d, n) 11C and 14N (d, n) 15O are presented using a Filippov-type plasma focus "Dena" as a breeder with the bank energy ranges from 20 to 90 kJ at the repetition rates from 1 to 10 Hz. The admixture gas pressure of 10B and 14 N were taken to be approximately 0.05 of initial working pressure at optimum neutron yield regime. The results obtained are discussed.

Zaeem, Alireza Asle; Mahmood Sadat Kiai, S.; Sedaghatizade, Mahmood; Adlparvar, Shirin; Sheibani, Shahab

2009-09-01

82

Short-lived radionuclides as monitors of early crust-mantle differentiation on the terrestrial planets  

NASA Astrophysics Data System (ADS)

The kinetic energy from large impacts, the gravitational energy released by core formation, and the heat provided by the decay of short-lived radioactive isotopes all drive extensive melting and chemical differentiation of silicate planets/planetesimals during and shortly after their formation. This early differentiation is best preserved on small objects such as the parent bodies of the eucrite and angrite meteorites where silicate melts were produced within 3 million years of solar system formation. The W isotopic composition of some iron meteorites testifies to core segregation on small planetesimals within as little as one million years or less of solar system formation. On larger objects, such as the Moon, Mars and Earth, the evidence for early differentiation provided by long-lived radioisotope systems has been variably overprinted by the continuing differentiation of these objects, but a clear signature of extensive early planet-scale differentiation is preserved in a variety of short-lived radioisotope systems, particularly, I-Pu-Xe, Hf-W and 146Sm- 142Nd. All these systems suggest that global differentiation of planetesimals and the terrestrial planets occurred during the first hundred million years of solar system history. This early processing of the Moon, Mars and Earth, may have fundamentally affected the evolution of these planets and their current internal compositional structure.

Carlson, Richard W.; Boyet, Maud

2009-03-01

83

Volatile properties of particles emitted by compressed natural gas and diesel buses during steady-state and transient driving modes.  

PubMed

Volatile properties of particle emissions from four compressed natural gas (CNG) and four diesel buses were investigated under steady-state and transient driving modes on a chassis dynamometer. The exhaust was diluted utilizing a full-flow continuous volume sampling system and passed through a thermodenuder at controlled temperature. Particle number concentration and size distribution were measured with a condensation particle counter and a scanning mobility particle sizer, respectively. We show that while almost all the particles emitted by the CNG buses were in the nanoparticle size range, at least 85% and 98% were removed at 100 and 250 C, respectively. Closer analysis of the volatility of particles emitted during transient cycles showed that volatilization began at around 40 C, with the majority occurring by 80 C. Particles produced during hard acceleration from rest exhibited lower volatility than those produced during other times of the cycle. On the basis of our results and the observation of ash deposits on the walls of the tailpipes, we suggest that these nonvolatile particles were composed mostly of ash from lubricating oil. Heating the diesel bus emissions to 100 C removed ultrafine particle numbers by 69-82% when a nucleation mode was present and just 18% when it was not. PMID:22107263

Jayaratne, E R; Meyer, N K; Ristovski, Z D; Morawska, L

2011-12-12

84

Collateral consequences of the inhomogeneous distribution of short-lived radionuclides in the solar nebula  

NASA Astrophysics Data System (ADS)

The presence of several short-lived (now extinct) radionuclides in the early solar system demands that they were synthesized and added to preexisting solar system materials shortly (on a time scale of the order of the relevant radionuclide lifetime) before formation of solar system solids. For diverse reasons it is often suggested that the solar system distributions of these radionuclides were radically heterogeneous, perhaps because of the late addition. Much attention has been given to the astrophysical circumstances that might govern the synthesis and distribution of these short-lived radionuclides, but comparatively little attention has been devoted to the distribution of co-synthesized isotopes. The focus of this paper is a systematic, quantitative evaluation of the collateral consequences in stable and long-lived isotopes which might be expected if short-lived radionuclides, in particular 26Al or 53Mn, were injected at their canonical levels and inhomogeneously distributed in the early solar system. We mix model massive star yields of Meyer et al. (1995) and Woosley and Weaver (1995) into a reservoir of cosmic composition, as tabulated by Anders and Grevesse (1989). To mitigate the effects of systematic deviations that may be present in these mixtures due to uncertainties in model stellar yields, we follow Timmes and Clayton (1996) and also mix into a "renormalized" proxy solar system composition computed from a galactic chemical evolution model based primarily on the stellar yields of Woosley and Weaver (1995). The results are very unfavorable to the likelihood of heterogeneously distributed 26Al derived from supernova ejecta. If a massive star is invoked to account for 26Al, its ejecta must have been rather uniformly distributed, as inferred from the lack of measured collateral anomalies in several elements, notably Ca, Cr and Ni. Conversely, if 26Al were indeed radically heterogeneously distributed, some other nucleosynthetic source, more efficient at producing 26Al, is required. In principle, a similar statement applies to 53Mn, but the situation is more complicated. The inferred anomalies at 53Cr will depend not only on how much 53Mn is added by a heterogeneous component, but also more sensitively on the contributions to the associated stable nuclides, 53Cr, 52Cr and 50Cr. Consideration of predicted collateral anomalies provides no direct support for heterogeneously-distributed supernova-derived 53Mn, but the required quantity of supernova contribution, and thus also the collateral anomalies, are much less for 53Mn than for 26Al. With allowance for model calculation uncertainties, it could be argued that anomalies collateral to heterogeneous 53Mn might be small enough to have evaded detection.

Nichols, Robert H., Jr.; Podosek, Frank A.; Meyer, Brad S.; Jennings, Cristine L.

1999-11-01

85

Massive stars and short-lived radionuclides in the Solar System  

NASA Astrophysics Data System (ADS)

Short-lived radionuclides (SLRs) are radioactive elements (T1/2 ? 200 Myr) which were present in the nascent solar system and are now extinct. While the initial abundance of SLRs with the longest half-lives (T1/2 ? 3 Myr) is compatible with the expectations of Galactic evolution models, others have a last-minute origin. 7Be, 10Be, 36Cl, and 41Ca probably originated within the protoplanetary disk from the irradiation of gas and dust by energetic particles accelerated by the protoSun. 26Al and 60Fe were probably synthesized by massive stars and added to interstellar gas which will eventually make up the bulk of our solar system. Identifying the detailed mechanisms of 26Al and 60Fe production and mixing will shed a light on the relationship between the Sun formation history and massive stars.

Gounelle, M.

2011-11-01

86

Inter-laboratory comparisons of short-lived gamma-emitting radionuclides in nuclear reactor water.  

PubMed

Inter-laboratory comparisons of gamma-emitting nuclides in nuclear power plant coolant water have been carried out in Finland since 1994. The reactor water samples are taken and prepared by one of the two nuclear power plants and delivered to the participants. Since all the participants get their sample within just a few hours it has been possible to analyse and compare results of nuclides with half-lives shorter than 1h. The total number of short-lived nuclides is 26. All the main nuclides are regularly identified and the activities have been obtained with reasonable accuracy throughout the years. The overall deviation of the results has decreased in 13 years. The effects of true coincidence summing and discrepancies in nuclear data have been identified as potential sources of remaining discrepancies. All the participants have found this type of comparison very useful. PMID:18378157

Klemola, S K

2008-02-21

87

Contribution of very short-lived substances to stratospheric bromine loading: uncertainties and constraints  

NASA Astrophysics Data System (ADS)

Very short-lived substances (VSLS) still represent a major factor of uncertainty in the quantification of stratospheric bromine loading. One of the major obstacles for short-lived source gases in contributing to the stratosphere is generally thought to be loss of inorganic bromine (Bry) in the tropical tropopause layer (TTL) due to dehydration. We use sensitivity calculations with a~three-dimensional chemistry transport model comprising a consistent parametrization of convective transport and a comprehensive chemistry scheme to investigate the associated processes. The model considers the two most important bromine VSLS, bromoform (CHBr3) and dibromomethane (CH2Br2). The organic bromine source gases as well as the resulting profile of inorganic bromine in the model are consistent with available observations. In contrast to its organic precursors, Bry is assumed to have a~significant sorption capacity regarding sedimenting liquid or frozen particles thus the fraction of intact source gases during their ascent through the TTL is a critical factor. We find that source gas injection is the dominant pathway into the stratosphere, about 50% of CHBr3 and 93% of CH2Br2 is able to overcome the cold point tropopause at approximately 17 km altitude, modulated by the interannual variability of the vertical transport efficiency. In fact, our sensitivity calculations indicate that the extent of source gas injection of CHBr3 is highly sensitive to the strength of convection and large-scale ascent; in contrast, modifying the photolysis or the destruction via OH yields a significantly smaller response. In principal, the same applies as well to CH2Br2, though it is considerably less responsive due to its longer lifetime. The next important aspect we identified is that the partitioning of available Bry from short-lived sources is clearly shifted away from HBr, according to our current state of knowledge the only member of the Bry family which is efficiently adsorbed on ice particles. This effect is caused by very efficient heterogeneous reactions on ice surfaces which reduce the HBr/Bry fraction below 15% at the tropical tropopause. Under these circumstances there is no significant loss of Bry due to dehydration in the model, VSLS contribute fully to stratospheric bromine. In addition, we conduct several sensitivity calculations to test the robustness of this result. If heterogeneous chemistry is ignored, the HBr/Bry fraction exceeds 50% and about 10% of bromine from VSLS is scavenged. Dehydration plays a minor role for Bry removal under the assumption that HOBr is efficiently adsorbed on ice as well since the heterogeneous reactions alter the partitioning equilibrium of Bry in favor of HOBr. In this case, up to 12% of bromine from VSLS is removed. Even in the extreme and unrealistic case that adsorbed species on ice particles are instantaneously removed the maximum loss of bromine does not exceed 25%. In conclusion, considering the average abundance of bromine short-lived source gases in convective updrafts of 6 parts per trillion by volume (pptv) we find a most likely contribution of VSLS to stratospheric bromine in the range of 4.5-6 pptv.

Aschmann, J.; Sinnhuber, B.-M.

2012-11-01

88

Contribution of very short-lived substances to stratospheric bromine loading: uncertainties and constraints  

NASA Astrophysics Data System (ADS)

Very short-lived substances (VSLS) still represent a major factor of uncertainty in the quantification of stratospheric bromine loading. One of the major obstacles for short-lived source gases in contributing to the stratosphere is generally thought to be loss of inorganic bromine (Bry) in the tropical tropopause layer (TTL) due to dehydration. We use sensitivity calculations with a three-dimensional chemistry transport model comprising a consistent parametrization of convective transport and a comprehensive chemistry scheme to investigate the associated processes. The model considers the two most important bromine VSLS, bromoform (CHBr3) and dibromomethane (CH2Br2). The organic bromine source gases as well as the resulting profile of inorganic bromine in the model are consistent with available observations. In contrast to its organic precursors, Bry is assumed to have a significant sorption capacity regarding sedimenting liquid or frozen particles thus the fraction of intact source gases during their ascent through the TTL is a critical factor. We find that source gas injection is the dominant pathway into the stratosphere, about 50% of CHBr3 and 94% of CH2Br2 is able to overcome the cold point tropopause at approximately 17 km altitude, modulated by the interannual variability of the vertical transport efficiency. In fact, our sensitivity calculations indicate that the extent of source gas injection of CHBr3 is highly sensitive to the strength of convection and large-scale ascent; in contrast, modifying the photolysis or the destruction via OH yields a significantly smaller response. In principle, the same applies as well to CH2Br2, though it is considerably less responsive due to its longer lifetime. The next important aspect we identified is that the partitioning of available Bry from short-lived sources is clearly shifted away from HBr, according to our current state of knowledge the only member of the Bry family which is efficiently adsorbed on ice particles. This effect is caused by very efficient heterogeneous reactions on ice surfaces which reduce the HBr/Bry fraction below 15% at the tropical tropopause. Under these circumstances there is no significant loss of Bry due to dehydration in the model, VSLS contribute fully to stratospheric bromine. In addition, we conduct several sensitivity calculations to test the robustness of this result. If heterogeneous chemistry is ignored, the HBr/Bry fraction exceeds 50% and about 10% of bromine from VSLS is scavenged. Dehydration plays a minor role for Bry removal under the assumption that HOBr is efficiently adsorbed on ice as well since the heterogeneous reactions alter the partitioning equilibrium of Bry in favor of HOBr. In this case, up to 12% of bromine from VSLS is removed. Even in the extreme and unrealistic case that adsorbed species on ice particles are instantaneously removed the maximum loss of bromine does not exceed 25%. Assuming 6 parts per trillion by volume (pptv) of bromine short-lived source gases in convective updrafts, a value that is supported by observational data, we find a most likely contribution of VSLS to stratospheric bromine in the range of 4.5-6 pptv.

Aschmann, J.; Sinnhuber, B.-M.

2013-02-01

89

Study of short-lived tin isotopes with a laser ion source  

SciTech Connect

A chemically selective laser ion source based on resonance ionization of atoms in a hot cavity was applied for study of short-lived tin isotopes at the heavy ion accelerator UNILAC/GSI. Tin atoms were ionized by a three-step resonance laser excitation of an autoionizing state. Yields of fusion-produced {sup 108}Sn and {sup 108}In isotopes were compared with the plasma ion source FEBIAD-B3. The total efficiency of tin ionization was determined to be 8.5%, whilst the indium isobar ionization was suppressed by a factor of 12. An experimental run on study of decay properties of extremely neutron deficient isotopes {sup 101-103}Sn has been carried out.

Fedoseyev, V. N.; Albus, F.; Kirchner, R.; Klepper, O.; Kluge, H.-J.; Mishin, V. I.; Passler, G.; Roeckl, E.; Scheerer, F.; Schmidt, K.; Trautmann, N. [Institute of Spectroscopy, Russian Academy of Sciences, 142092, Trotzk (Russian Federation); Institut fuer Physik, Universitaet Mainz, D-55029 Mainz (Germany); GSI-Darmstadt, D-64220 Darmstadt (Germany); Institut fuer Physik, Universitaet Mainz, D-55029 Mainz (Germany); Institute of Spectroscopy, Russian Academy of Sciences, 142092, Trotzk (Russian Federation); Institut fuer Physik, Universitaet Mainz, D-55029 Mainz (Germany); GSI-Darmstadt, D-64220 Darmstadt (Germany); Institut fuer Kernchemie, Universitaet Mainz, D-55029 Mainz (Germany); GSI-Darmstadt, D-64220 Darmstadt (Germany); Institut fuer Kernchemie, Universitaet Mainz, D-55029 Mainz (Germany)

1995-04-01

90

Neutron-induced capture cross sections of short-lived actinides with the surrogate reaction method  

NASA Astrophysics Data System (ADS)

Determination of neutron-capture cross sections of short-lived nuclei is opening the way to understand and clarify the properties of many nuclei of interest for nuclear structure physics, nuclear astrophysics and particularly for transmutation of nuclear wastes. The surrogate approach is well-recognized as a potentially very useful method to extract neutron cross sections for low-energy compound-nuclear reactions and to overcome the difficulties related to the target radioactivity. In this work we will assess where we stand on these neutron-capture cross section measurements and how we can achieve the short-lived Minor Actinides nuclei involved in the nuclear fuel cycle. The CENBG collaboration applied the surrogate method to determine the neutron-capture cross section of 233Pa (T1/2 = 27 d). The 233Pa (n,?) cross section is then deduced from the measured gamma decay probability of 234Pa compound nucleus formed via the surrogate 232Th(3He,p) reaction channel. The obtained cross section data, covering the neutron energy range 0.1 to 1 MeV, have been compared with the predictions of the Hauser-Feshbach statistical model. The importance of establishing benchmarks is stressed for the minor actinides region. However, the lack of desired targets led us to propose recently the 174Yb (3He,p?) reaction as a surrogate reaction for the (n,?) predetermined benchmark cross section of 175Lu. An overview of the experimental setup combining gamma ray detectors such as Ge and C6D6 in coincidence with light charged particles ?E-E Telescopes will be presented and preliminary results will be discussed.

Ache, M.; Boutoux, G.; Jurado, B.; Barreau, G.; Matthieu, L.; Czajkowski, S.; Dassie, D.; Haas, B.; Mot, V.; Roig, O.; Gaudefroy, L.; Taieb, J.; Pillet, N.; Faul, T.; Srot, O.; Bauge, E.; Gunsing, F.

2010-03-01

91

Seeds of alpine plants are short lived: implications for long-term conservation  

PubMed Central

Background and Aims Alpine plants are considered one of the groups of species most sensitive to the direct and indirect threats to ecosystems caused by land use and climate change. Collecting and banking seeds of plant species is recognized as an effective tool for providing propagating material to re-establish wild plant populations and for habitat repair. However, seeds from cold wet environments have been shown to be relatively short lived in storage, and therefore successful long-term seed conservation for alpine plants may be difficult. Here, the life spans of 69 seed lots representing 63 related species from alpine and lowland locations from northern Italy are compared. Methods Seeds were placed into experimental storage at 45 C and 60 % relative humidity (RH) and regularly sampled for germination. The time taken in storage for viability to fall to 50 % (p50) was determined using probit analysis and used as a measure of relative seed longevity between seed lots. Key Results Across species, p50 at 45 C and 60 % RH varied from 47 to 955 d. Seed lots from alpine populations/species had significantly lower p50 values compared with those from lowland populations/species; the lowland seed lots showed a slower rate of loss of germinability, higher initial seed viability, or both. Seeds were progressively longer lived with increased temperature and decreased rainfall at the collecting site. Conclusions Seeds of alpine plants are short lived in storage compared with those from lowland populations/related taxa. The lower resistance to ageing in seeds of alpine plants may arise from low selection pressure for seed resistance to ageing and/or damage incurred during seed development due to the cool wet conditions of the alpine climate. Long-term seed conservation of several alpine species using conventional seed banking methods will be problematic.

Mondoni, Andrea; Probert, Robin J.; Rossi, Graziano; Vegini, Emanuele; Hay, Fiona R.

2011-01-01

92

Seasonal Short-Lived Radium Activity in the Venice Lagoon: The Role of Residence Time  

NASA Astrophysics Data System (ADS)

Radium is considered to be an excellent tracer of submarine groundwater discharge (SGD) and, therefore, has been used in many studies of this process in the past decade. Comprehensive surveys of excess 223,224Ra activity were completed in the surface waters of the Venice Lagoon over 6 seasons in order to quantify seasonal variation of SGD into the lagoon. The mass balance of radium found that SGD was 5-26 times greater than total river discharge (35.5 m3 s-1), and that total SGD could differ by almost an order of magnitude pending season. Several possible parameters, which may cause the seasonal variation, were tested. These included precipitation events, average tidal elevation, average tidal excursion, wind speed and direction, yet none provided a satisfactory explanation for the difference. Residence time based on a hydrodynamic model, however, was very strongly correlated with the observed variation. When the average residence time in the lagoon was low (5 days) the SGD was calculated to be 930 m3 s-1 and when the average residence time was high (9 days) the SGD was quantified as 160 m3 s-1. Radioactive decay is already accounted for in the mass balance model and therefore this correlation must be explained by another process. The Venice Lagoon is characterized by low residence time during periods of spring tides and bora or northerly winds, both of which create exceptionally strong currents in the Venice Lagoon. The currents as well as the large tidal excursion which occurs at spring tides drive a recirculation of seawater through the surface sediments, which greatly increases short-lived Ra activity in the surface waters. This evidence suggests, therefore, that short-lived Ra mass balance studies, which are based on a single survey, may under or overestimate the mean annual SGD pending the hydrodynamics of the investigated location.

Rapaglia, J.; Ferrarin, C.; Zaggia, L.; Umgiesser, G.; Zuppi, G.; Manfe', G.

2008-12-01

93

Comparative in vitro microdosimetric study of murine- and human-derived cancer cells exposed to alpha particles.  

PubMed

Diffusing alpha-emitter radiation therapy (DaRT) is a proposed new form of brachytherapy using ? particles to treat solid tumors. The method relies on implantable ?Ra-loaded sources that continually release short-lived ?-particle-emitting atoms that spread inside the tumor over a few millimeters. This treatment was demonstrated to have a significant effect on tumor growth in murine and human-derived models, but the degree of tumor response varied across cell lines. Tumor response was found to correlate with the degree of radionuclide spread inside the tumor. In this work we examined the radiosensitivity of individual cells to determine its relationship to tumor response. Cells were irradiated in vitro by ? particles using a ?Th irradiator, with the mean lethal dose, D?, estimated from survival curves generated by standard methods. The results were further analyzed by microdosimetric tools to calculate z?, the specific energy resulting in a survival probability of 1/e for a single cell, which is considered to better represent the intrinsic radiosensitivity of individual cells. The results of the study demonstrate that, as a rule, tumors that respond more favorably to the DaRT treatment are also characterized by higher intrinsic cellular radiosensitivities, with D? ranging from 0.7 Gy to 1.5 Gy for the extreme cases and z? following the same trend. PMID:22077335

Lazarov, E; Arazi, L; Efrati, M; Cooks, T; Schmidt, M; Keisari, Y; Kelson, I

2011-11-11

94

Unattached fraction of short-lived Rn decay products in indoor and outdoor environments: An improved single-screen method and results  

SciTech Connect

The unattached fraction fp of potential alpha energy of short-lived Rn decay products was measured under realistic, natural conditions in different dwellings and in the open atmosphere by a single-screen technique. An improved data evaluation method was developed where the measured activities of {sup 218}Po (RaA) and {sup 214}Pb (RaB) were corrected by the screen-attached activities of {sup 214}Bi ({sup 214}Po) (RaC (RaC')). This method is based on the experimental observation that the {sup 214}Bi ({sup 214}Po) unattached activities are negligible under realistic living conditions and that the size distributions of the aerosol-attached activities of all short-lived Rn daughters are identical. In closed rooms without additional aerosol sources, a mean unattached fraction fp of the potential alpha energy of 0.096 was obtained at a mean aerosol particle concentration of 6100 cm-3 and at a mean equilibrium factor F of 0.30. This mean fp value is about three times higher than the value used in the literature for the radiation exposure calculation of the human public. In closed rooms with additional aerosol sources (cigarette smoke, heating systems, aerosols from a burning candle), the aerosol particle concentrations ranged up to 10(6) cm-3 and the attachment rates, X, increased up to 1000 h-1. The fp values sometimes decreased below the detection limit of 0.005, and the F values increased to as high as 0.77. In the ambient atmosphere in the vicinity of Goettingen, a mean unattached fraction fp of 0.02 and a mean aerosol particle concentration of 3.4 x 10(4) cm-3 were measured at 1 m above the ground. The mean equilibrium factor F was determined to be 0.7.A

Reineking, A.; Porstendoerfer, J. (Universitaet Goettingen (Germany, F.R.))

1990-06-01

95

Simulation and optimization of cyclic activation analysis of short-lived isotopes with 14MeV neutron generator.  

PubMed

A program of simulation and optimization is developed for the case of cyclic activation analysis of short-lived isotopes with 14-MeV neutrons. The background line under the photopeaks of interest is simulated using Zikovsky's model. The reliability of the program is checked on real conditions with a geological reference sample "Soil 5" provided by the IAEA. Optimum experimental conditions (timing parameters, number of cycles) are determined, and corresponding detection limits calculated. A systematic study of short-lived isotopes with half-lives lower than 5 min is done for Soil 5, and the results are discussed. PMID:7710887

Khelifi, R; Idiri, Z; Tobbeche, S

1994-01-01

96

Uncertainties and constraints regarding the contribution of very short-lived substances to stratospheric bromine loading  

NASA Astrophysics Data System (ADS)

A major factor of uncertainty in the assessment of stratospheric bromine loading is the unclear role of very short-lived substances (VSLS). One of the major obstacles for short-lived source gases in contributing to the stratosphere is generally thought to be the loss of inorganic bromine (Bry) in the tropical tropopause layer due to dehydration. Besides the dehydration process itself, transportation pathways and velocities are also of vital importance as they influence the partitioning between mostly insoluble organic source gases and partly soluble inorganic degradation products. To investigate this complex system we employ an extensive set of sensitivity calculations with a three-dimensional chemistry transport model comprising a consistent parameterization of convective transport and a comprehensive chemistry scheme. The model considers the two most important bromine VSLS, bromoform (CHBr3) and dibromomethane (CH2Br2) assuming a fixed and uniform detrainment mixing ratio of 1 pptv each. Despite our simplified approach our model agrees reasonably well with available observations of bromine source and product gases. We find that source gas injection is the dominant pathway for VSLS into the stratosphere; about 50% of CHBr3 and 93% of CH2Br2 is able to overcome the cold point tropopause at approximately 17 km altitude, modulated by the inter-annual variability of the vertical transport efficiency. In fact, our sensitivity calculations indicate that the extent of source gas injection of CHBr3 is highly sensitive to the strength of convection and large-scale ascent; in contrast, modifying the photolysis or the destruction via OH yields a significantly smaller response. The next important aspect we identified is that the partitioning of available Bry from short-lived sources is clearly shifted away from HBr, according to our current state of knowledge the only member of the Bry family which is efficiently adsorbed on ice particles. This effect is caused by very efficient heterogeneous reactions on ice surfaces which reduce the HBr/Bry fraction below 15% at the tropical tropopause. Under these circumstances there is no significant loss of Bry due to dehydration in the model; VSLS contribute fully to stratospheric bromine. In addition, we conduct several sensitivity calculations to test the robustness of this result. The loss of inorganic bromine is not very sensitive to moderate changes of the involved parameters such as the abundance of water vapor, sedimentation velocity of particles or ice uptake coefficients. However, dehydration may play a minor role for Bry removal under the assumption that HOBr is efficiently adsorbed on ice as well since the heterogeneous reactions alter the partitioning equilibrium of Bry in favor of HOBr (up to 12% loss of bromine from VSLS). Even in the extreme and unrealistic case that adsorbed species on ice particles are instantaneously removed the maximum loss of bromine does not exceed 25%.

Aschmann, Jan; Sinnhuber, Bjrn-Martin

2013-04-01

97

AGB stars as a source of short-lived radioactive nuclei in the solar nebula  

NASA Astrophysics Data System (ADS)

The purpose is to estimate the possible contribution of some short-lived nuclei to the early solar nebula from asymptotic giant branch (AGB) sources. Low mass (1 to 3 solar mass) AGB stars appear to provide a site for synthesis of the main s process component for solar system material with an exponential distribution of neutron irradiations varies as exp(-tau/tau0) (where tau is the time integrated neutron flux with a mean neutron exposure tau0) for solar abundances with tau0 = 0.28 mb-1. Previous workers estimated the synthesis of key short-lived nuclei which might be produced in AGB stars. While these calculations exhibit the basic characteristics of nuclei production by neutron exposure, there is need for a self-consistent calculation that follows AGB evolution and takes into account the net production from a star and dilution with the cloud medium. Many of the general approaches and the conclusions arrived at were presented earlier by Cameron. The production of nuclei for a star of 1.5 solar mass during the thermal pulsing of the AGB phase was evaluated. Calculations were done for a series of thermal pulses with tau0 = 0.12 and 0.28 mb-1. These pulses involve s nucleosynthesis in the burning shell at the base of the He zone followed by the ignition of the H burning shell at the top of the He zone. After about 10-15 cycles the abundances of the various nuclei in the He zone become constant. Computations of the abundances of all nuclei in the He zone were made following Gallino. The mass of the solar nebula was considered to consist of some initial material of approximately solar composition plus some contributions from AGB stars. The ratios of the masses required from the AGB He burning zone to the ISM necessary to produce the observed value of Pd-107/Pd-108 in the early solar system were calculated and this dilution factor was applied to all other relevant nuclei.

Wasserburg, G. J.; Gallino, R.; Busso, M.; Raiteri, C. M.

1993-03-01

98

Senescence Is More Important in the Natural Lives of Long- Than Short-Lived Mammals  

PubMed Central

Background Senescence has been widely detected among mammals, but its importance to fitness in wild populations remains controversial. According to evolutionary theories, senescence occurs at an age when selection is relatively weak, which in mammals can be predicted by adult survival rates. However, a recent analysis of senescence rates found more age-dependent mortalities in natural populations of longer lived mammal species. This has important implications to ageing research and for understanding the ecological relevance of senescence, yet so far these have not been widely appreciated. We re-address this question by comparing the mean and maximum life span of 125 mammal species. Specifically, we test the hypothesis that senescence occurs at a younger age relative to the mean natural life span in longer lived species. Methodology/Principal Findings We show, using phylogenetically-informed generalised least squares models, a significant log-log relationship between mean life span, as calculated from estimates of adult survival for natural populations, and maximum recorded life span among mammals (R2?=?0.57, p<0.0001). This provides further support for a key prediction of evolutionary theories of ageing. The slope of this relationship (0.3530.052 s.e.m.), however, indicated that mammals with higher survival rates have a mean life span representing a greater fraction of their potential maximum life span: the ratio of maximum to mean life span decreased significantly from >10 in short-lived to ?1.5 in long-lived mammal species. Conclusions/Significance We interpret the ratio of maximum to mean life span to be an index of the likelihood an individual will experience senescence, which largely determines maximum life span. Our results suggest that senescence occurs at an earlier age relative to the mean life span, and therefore is experienced by more individuals and remains under selection pressure, in long- compared to short-lived mammals. A minimum rate of somatic degradation may ultimately limit the natural life span of mammals. Our results also indicate that senescence and modulating factors like oxidative stress are increasingly important to the fitness of longer lived mammals (and vice versa).

Turbill, Christopher; Ruf, Thomas

2010-01-01

99

Long- and short-lived nuclide constraints on the recent evolution of permafrost soils  

NASA Astrophysics Data System (ADS)

Frozen permafrost ecosystems are particularly sensitive to climate warming, which notably induces a deepening of the active layer (the maximum thawing depth during summer time). As a consequence, geochemical and hydrological fluxes within boreal areas are expected to be significantly affected in the future. Understanding the relationship between environmental changes and permafrost modifications is then a major challenge. This work aims to evaluate in a Siberian watershed the dynamics of the permafrost active layer and their recent modifications by combining a classic study of long-lived nuclides to the study of short-lived nuclides of U and Th decay series. Two soil profiles, located on opposite slopes (north- and south-facing slopes) of the Kulingdakan watershed (Putorana Plateau, Central Siberia), were sampled at several depths within the active layer and (238U), (234U), (232Th), (230Th), (226Ra), (228Ra), (228Th) and (210Pb) were measured on bulk soil samples by TIMS or gamma spectrometry. Our results show that south-facing and north-facing soil profiles are significantly different in terms of evolution of chemical concentrations and nuclide activities; north-facing soil profile is strongly affected by atmospheric inputs whereas long-lived nuclide dynamics within south-facing soil profile are dominated by weathering and exhibit more complex patterns. The amount of above-ground biomass being the single varying parameter between the two slopes of the watershed, we suggest that the structuring of permafrost active layer is very sensitive to vegetation activity and that the functioning of boreal soils will be significantly modified by its development due to more favorable climatic conditions. Moreover, the coupling of long and short-lived nuclides highlights the superimposition of a recent mobilization of chemical elements within soils (<10 years) over a much older soil structure (>8000 years), which can be observed for both soil profiles. The shallowest layer of the north-facing soil profile presents a recent increase of Th leaching that we link to the development of vegetation activity and/or organic matter degradation. In contrast, recent changes within south-facing soil profile affect the deepest part of the active layer, suggesting its deepening as a result of a global warming of Siberian soils.

Bagard, M.; Chabaux, F. J.; Rihs, S.; Pokrovsky, O. S.; Prokushkin, A. S.; Viers, J.

2011-12-01

100

Short-lived Be and Be In Refractory Inclusions From 7 10  

NASA Astrophysics Data System (ADS)

The source of 26Al [1] and other short-lived radioactive nuclides (e.g. 41Ca or 53Mn) found in Ca-Al-rich refractory inclusions (CAIs) of chondritic meteorites is still controversial between the tenants of an external seeding of the protosolar nebula (e.g. by supernova produced Al) and the tenants of an internal source of 26 26Al within the solar system (e.g. by irradiation processes occurring in the vicinity of the young Sun). The resolution of this issue is of importance for (i) early solar system chronology and for (ii) models of the formation of the solar system. Recently we showed that 10Be, which decays to B with a half-life of 1.5 My, was 10 also incorporated in CAIs during their formation [2]. The incorporation of 10 Be in CAIs is a strong hint for the existence of irradiation processes that may have occurred in the early solar system, producing 10Be and a fraction (or all) of other extinct radioactive nuclides. However, because of its long half life, 10Be could have been produced by spallation reactions taking place in supernovae envelopes and transported into the protosolar nebula. To progress in this debate we have looked for traces of another short-lived isotope of Be, Be which decays to Li 7 7 with a half life of 53 days. Large Li isotopic variations have been found in a few Allende CAIs, with 7Li excesses positively correlated to Be/Li concentration ratios. These observations are best explained by the incorporation of lived Be in 7 CAIs during their formation. The Be/10Be ratio which is deduced for CAIs is of 7 220+/-130, i.e. close within errors to the production ratio modelled for irradiation processes at low energy around the young Sun. Because of its very short half life of 53 days, the presence of Be in CAIs demonstrates that Be (and 7 7 10Be) were produced within the solar system. It is also a strong indication that the formation of CAIs was likely linked in space and time to these irradiation processes. [1] T. Lee, D. Papanastassiou and G. J. Wasserburg (1976) Geophys. Res. Lett., 3, 109-112. [2] K. D. McKeegan, M. Chaussidon, F. Robert (2000) Science 289, 1334-1347.

Allende Meteorite, The

101

Allograft rejection is restrained by short-lived TIM-3+PD-1+Foxp3+ Tregs  

PubMed Central

Tregs play a pivotal role in inducing and maintaining donor-specific transplant tolerance. The T cell immunoglobulin and mucin domain-3 protein (TIM-3) is expressed on many fully activated effector T cells. Along with program death 1 (PD-1), TIM-3 is used as a marker for exhausted effector T cells, and interaction with its ligand, galectin-9, leads to selective death of TIM-3+ cells. We report herein the presence of a galectin-9sensitive CD4+FoxP3+TIM-3+ population of T cells, which arose from CD4+FoxP3+TIM-3 proliferating T cells in vitro and in vivo and were often PD-1+. These cells became very prominent among graft-infiltrating Tregs during allograft response. The frequency and number of TIM-3+ Tregs peaked at the time of graft rejection and declined thereafter. Moreover, these cells also arise in a tolerance-promoting donor-specific transfusion model, representing a pool of proliferating, donor-specific Tregs. Compared with TIM-3 Tregs, TIM-3+ Tregs, which are often PD-1+ as well, exhibited higher in vitro effector function and more robust expression of CD25, CD39, CD73, CTLA-4, IL-10, and TGF-? but not galectin-9. However, these TIM-3+ Tregs did not flourish when passively transferred to newly transplanted hosts. These data suggest that a heretofore unrecognized graft-infiltrating, short-lived subset of Tregs can restrain rejection.

Gupta, Shipra; Thornley, Thomas B.; Gao, Wenda; Larocca, Rafael; Turka, Laurence A.; Kuchroo, Vijay K.; Strom, Terry B.

2012-01-01

102

Direct detection and reactivity of the short-lived phenyloxenium ion.  

PubMed

Photolysis of protonated phenylhydroxylamine was studied using product analysis, trapping experiments, and laser flash photolysis experiments (UV-vis and TR(3) detection) ranging from the femtosecond to the microsecond time scale. We find that the excited state of the photoprecursor is followed by two species: a longer-lived transient (150 ns) that we assign to the phenoxy radical and a shorter-lived (3-20 ns) transient that we assign to the singlet phenyloxenium ion. Product studies from photolysis of this precursor show rearranged protonated o-/p-aminophenols and solvent water adducts (catechol, hydroquinone) and ammonium ion. The former products can be largely ascribed to radical recombination or ion recombination, while the latter are ascribed to solvent water addition to the phenyloxenium ion. The phenyloxenium ion is apparently too short-lived under these conditions to be trapped by external nucleophiles other than solvent, giving only trace amounts of o-/p-chloro adducts upon addition of chloride trap. Product studies upon thermolysis of this precursor give the same products as those generated from photolysis, with the difference being that the ortho adducts (o-aminophenol, hydroquinone) are formed in a higher ratio in comparison to the photolysis products. PMID:23713909

Hanway, Patrick J; Xue, Jiadan; Bhattacharjee, Ujjal; Milot, Maeia J; Ruixue, Zhu; Phillips, David Lee; Winter, Arthur H

2013-06-07

103

Yields of short-lived fission products produced following 235U(nth,f)  

NASA Astrophysics Data System (ADS)

Measurements of gamma-ray spectra, following the thermal neutron fission of 235U have been made using a high purity germanium detector at the University of Massachusetts Lowell (UML) Van de Graaff facility. The gamma spectra were measured at delay times ranging from 0.2 s to nearly 10 000 s following the rapid transfer of the fission fragments with a helium-jet system. On the basis of the known gamma transitions, forty isotopes have been identified and studied. By measuring the relative intensities of these transitions, the relative yields of the various precursor nuclides have been calculated. The results are compared with the recommended values listed in the ENDF/B-VI fission product data base (for the lifetimes and the relative yields) and those published in the Nuclear Data Sheets (for the beta branching ratios). This information is particularly useful for the cases of short-lived fission products with lifetimes of the order of fractions of a second or a few seconds. Independent yields of many of these isotopes have rather large uncertainties, some of which have been reduced by the present study.

Tipnis, S. V.; Campbell, J. M.; Couchell, G. P.; Li, S.; Nguyen, H. V.; Pullen, D. J.; Schier, W. A.; Seabury, E. H.; England, T. R.

1998-08-01

104

Large Differences in Aging Phenotype between Strains of the Short-Lived Annual Fish Nothobranchius furzeri  

PubMed Central

Background A laboratory inbred strain of the annual fish Nothobranchius furzeri shows exceptionally short life expectancy and accelerated expression of age markers. In this study, we analyze new wild-derived lines of this short-lived species. Methodology/Principal Findings We characterized captive survival and age-related traits in F1 and F2 offspring of wild-caught N. furzeri. Wild-derived N. furzeri lines showed expression of lipofuscin and neurodegeneration at age 21 weeks. Median lifespan in the laboratory varied from to 20 to 23 weeks and maximum lifespan from 25 to 32 weeks. These data demonstrate that rapid age-dependent decline and short lifespan are natural characteristics of this species. The N. furzeri distribution range overlaps with gradients in altitude and aridity. Fish from more arid habitats are expected to experience a shorter survival window in the wild. We tested whether captive lines stemming from semi-arid and sub-humid habitats differ in longevity and expression of age-related traits. We detected a clear difference in age-dependent cognitive decline and a slight difference in lifespan (16% for median, 15% for maximum lifespan) between these lines. Finally, we observed shorter lifespan and accelerated expression of age-related markers in the inbred laboratory strain compared to these wild-derived lines. Conclusions/Significance Owing to large differences in aging phenotypes in different lines, N. furzeri could represent a model system for studying the genetic control of life-history traits in natural populations.

Benedetti, Mauro; Roncaglia, Paola; Cattaneo, Antonino; Domenici, Luciano; Cellerino, Alessandro

2008-01-01

105

Supernova injection of short-lived radionuclides into the presolar cloud: A feasibility study  

NASA Astrophysics Data System (ADS)

Meteorite inclusions show that the early solar system was radioactive with species of short lifetimes compared to the formation time of the solar system. Transporting the radioactive material from the creation site to the formation site of the sun was expected to take enough time that these species should have decayed to nonexistence. Some special series of events seems necessary to speed the process along. Cameron & Truran (1977) suggested that the source of these short-lived radionuclides could have been a supernova. Numerical hydrodynamic studies have shown that slow shockwaves can inject material into a small, dense cloud core. Most stars are not born in lone dense cores. Thus any core that might have become the solar system was probably shrouded with an envelope that the ejecta from supernova would have had to penetrate along with the intervening interstellar medium. We present numerical hydrodynamic studies using Zeus-2D investigating how a supernova can inject its material into a moderately dense molecular cloud. We model a self-similar explosion colliding with a spherical cloud and examine the results for injection. We have modified Zeus-2D by adding three tracking dyes and changing the effective adiabatic index of the fluid in response to the shock-cloud collision. We find that if the effective adiabatic index of the gas is less than 5/3 then injection can occur, and we describe the basics of the mechanism by which this occurs.

Davis, Keith W.

106

Highlighting short-lived excited electronic states with pump-degenerate-four-wave-mixing  

NASA Astrophysics Data System (ADS)

Detection of short-lived transient species is a major challenge in femtosecond spectroscopy, especially when third-order techniques like transient absorption are used. Higher order methods employ additional interactions between light and matter to highlight such transient species. In this work we address numerically and experimentally the detection of ultrafast species with pump-Degenerate Four Wave Mixing (pump-DFWM). In this respect, conclusive identification of ultrafast species requires the proper determination of time-zero between all four laser pulses (pump pulse and the DFWM sequence). This is addressed here under the light of experimental parameters as well as molecular properties: The role of pulse durations, amount of pulse chirp as well as excited state life time is investigated by measuring a row of natural pigments differing mainly in the number of conjugated double bonds (N = 9 to 13). A comparison of the different signals reveals a strikingly unusual behavior of spheroidene (N = 10). Complete analysis of the pump-DFWM signal illustrates the power of the method and clearly assigns the uniqueness of spheroidene to a mixing of the initially excited state with a dark excited electronic state.

Marek, Marie S.; Buckup, Tiago; Southall, June; Cogdell, Richard J.; Motzkus, Marcus

2013-08-01

107

Short-lived protease-serpin complexes: Partial disruption of the rat trypsin active site  

PubMed Central

Serpins inhibit serine proteases by mechanically disrupting the protease active site. The protease first reacts with the serpin's reactive center loop (RCL) to form an acylenzyme. Then the RCL inserts into a ?-sheet in the body of the serpin, translocating the attached protease ?70 and deforming the protease active site, thereby trapping the acylenzyme. Loop insertion (?1 s?1) is an order of magnitude slower than hydrolysis of a typical substrate acylenzyme (?50 s?1), indicating that the protease is inhibited during translocation. We have previously trapped a partially translocated covalent complex of rat trypsin and ?1-proteinase inhibitor (EpartI*) resulting from attractive interactions between cationic dyes and anionic rat trypsin. Here, using single pair Frster resonance energy transfer, we demonstrate that EpartI* is a metastable complex that can dissociate to free protease and cleaved serpin (I*) as well as convert to the canonical fully translocated complex EfullI*. The partitioning between these two pathways is pH dependent, with conversion favored at low pH and dissociation favored at high pH. The short lifetime of EpartI* (?3 h at pH 7.4) and the pH dependence of EpartI* dissociation suggest that, unlike in EfullI*, the catalytic triad is intact in EpartI*. These results also demonstrate that interactions between target proteases and the body of the serpin can hinder protease translocation leading to short-lived covalent complexes.

Liu, Lu; Mushero, Nicole; Hedstrom, Lizbeth; Gershenson, Anne

2007-01-01

108

Harvard-MIT research program in short-lived radiopharmaceuticals. Final report  

SciTech Connect

The Harvard-MIT Research Program in Short-lived Radiopharmaceuticals was established in 1977 to foster interaction among groups working in radiopharmaceutical chemistry at Harvard Medical School, the Massachusetts Institute of Technology, and the Massachusetts General Hospital. To this was added a group at The Childrens Hospital. From these collaborations and building upon the special strengths of the participating individuals, laboratories and institutions, it was hoped that original approaches would be found for the design of new, clinically useful, radiolabeled compounds. The original thrust of this proposal included: (a) examination of the coordination chemistry of technetium as a basis for rational radiopharmaceutical design, (b) development of an ultrashort-lived radionuclide generator for the diagnosis of congenital heart disease in newborns, (c) synthesis of receptor-site-directed halopharmaceuticals, (d) improved facile labeling of complex molecules with positron-emitting radionuclides. The authors` 1986 proposal was oriented toward organs and disease, emphasizing radiolabeled agents that delineate specific functions and the distribution of receptors in brain, heart, and tumors. In 1989, they further refined their purposes and focused on two major aims: (a) synthesis and utilization of neutral technetium and rhenium complexes of high specific activity, and (b) development of new approaches to the radiolabeling of proteins, peptides, immunoglobulins, and their fragments. In 1992, the authors amended this proposal to concentrate their efforts on biologically active peptides and proteins for targeted radiodiagnosis and therapy.

Adelstein, S.J. [Massachusetts Inst. of Tech., Cambridge, MA (United States). Office of Sponsored Programs

1995-02-01

109

Spatial distribution of brominated very short-lived substances in the eastern Pacific  

NASA Astrophysics Data System (ADS)

Seawater concentrations and distributions of brominated very short-lived substances (BrVSLS), including bromoform (CHBr3), dibromomethane (CH2Br2), bromodichloromethane (CHBrCl2), chlorodibromomethane (CHClBr2), were measured in the upper water column (5-750 m) in the eastern Pacific. Inorganic nutrient, pigment concentrations, and picoplankton cell counts were measured to determine biogeochemical factors that affect the production and distribution of these BrVSLS. Elevated concentrations of BrVSLS were observed in coastal and tropical seawater. Concentration maxima for CHBr3, CH2Br2, and CHClBr2 were observed below the mixed layer, near the subsurface chlorophyll a maxima, which suggest BrVSLS production may be related to photosynthetic biomass production. Our results also suggest that heterotrophic bacteria may also contribute to CH2Br2 and CHBrCl2 production in the water column. The maximum CHBrCl2 concentration was observed at a depth much deeper than the euphotic zone, which suggests sources other than photosynthetic biomass. Elevated CHBrCl2 concentrations in deeper waters were coincident with elevated CHCl3 concentrations, which may be an evidence for successive chlorine substitution of CHBr3 in deeper and older water masses.

Liu, Yina; Yvon-Lewis, Shari A.; Thornton, Daniel C. O.; Campbell, Lisa; Bianchi, Thomas S.

2013-05-01

110

Large-Scale, Short-Lived Subduction of the Western Gneiss Region Ultrahigh-Pressure Terrane  

NASA Astrophysics Data System (ADS)

The Western Gneiss Region (WGR) of Norway includes one of Earth's giant ultrahigh-pressure (UHP) terranes. Understanding the subduction and exhumation of this >60,000 km2 area is relevant to a range of processes, including collisional orogenesis, reworking of the continents, and the global geochemical cycle. Important aspects that remain unanswered include the spatial and temporal style of subduction. Was the crust subducted as smaller slivers one at a time, or as one larger unit, all at the same time? The WGR exhibits consistent ages of ~415-400 Ma, 100+ km along strike, but no ages have been identified at an equivalent distance across strike. To address this issue we have determined the age of one of the easternmost eclogites identified in the WGR, a retrogressed eclogite from Lesja. Seven fractions of this sample were analyzed; six of them yield identical U/Pb ages, however, they are slightly discordant. The seventh fraction is anomalously young and interpreted to have suffered lead loss. A weighted-mean 206Pb/238U age of 408.0 1.7 Ma is obtained from the six older fractions; an age that is within the range of U/Pb, Sm/Nd, and Lu/Hf ages from the western portion of the WGR. The similarity in ages from 100+ km north to south and 100+ km east to west indicate that large portions of the continental crust were subducted in a short-lived event, if not en masse.

Kylander-Clark, A. R.; Hacker, B. R.; Corfu, F.

2006-12-01

111

Simulating Supernova Injection of Short Lived Radionuclides with Consideration of the Solar Birth Environment  

NASA Astrophysics Data System (ADS)

The existence of short-lived radionuclides (SLRNs) in the early solar system above their background galactic abundances is well accepted. Studies into the relative abundances and possible sources for radioisotopes indicate a model with three separate sources for the total abundance of SLRNs: the background galactic value, material from some nearby stellar source, and in-situ creation by the early active Sun. A type II SN may be the most likely source for the stellar component, specifically 60Fe. The geometric details of the stellar birth are largely unknown despite evidence that the presolar cloud was not isolated. From a hydrodynamic perspective, the injection of SLRNs may be difficult because of intervening material between the core and the explosion necessary to slow the shock speed enough that the core is compressed rather than shredded. For the SN component it is vital to understand how SN ejecta can reach a core and whether certain SN/cloud environments are precluded by the hydrodynamics. We present Zeus-2D simulations studying the possibility of SLRN injection into a presolar core that is part of a larger cloud complex.

Davis, Keith W.; Leising, M. D.

2006-12-01

112

Short telomeres in short-lived males: what are the molecular and evolutionary causes?  

PubMed

Telomere length regulation is an important aspect of cell maintenance in eukaryotes, since shortened telomeres can lead to a number of defects, including impaired cell division. Although telomere length is correlated with lifespan in some bird species, its possible role in aging and lifespan determination is still poorly understood. Here we investigate telomere dynamics (changes in telomere length and attrition rate) and telomerase activity in the ant Lasius niger, a species in which different groups of individuals have evolved extraordinarily different lifespans. We found that somatic tissues of the short-lived males had dramatically shorter telomeres than those of the much longer-lived queens and workers. These differences were established early during larval development, most likely through faster telomere shortening in males compared with females. Workers did not, however, have shorter telomeres than the longer-lived queens. We discuss various molecular mechanisms that are likely to cause the observed sex-specific telomere dynamics in ants, including cell division, oxidative stress and telomerase activity. In addition, we discuss the evolutionary causes of such patterns in ants and in other species. PMID:17346255

Jemielity, Stephanie; Kimura, Masayuki; Parker, Karen M; Parker, Joel D; Cao, Xiaojian; Aviv, Abraham; Keller, Laurent

2007-03-07

113

Integrated measurements of short-lived 222Rn progeny by rotating filters.  

PubMed

The dependence of the risk from inhalation of radon progeny on their disequilibrium suggests that the measurements of the time-integrated concentrations of each of the short-lived radon progeny are necessary for complete risk estimations. This paper presents a method that, in principle, allows the determination of the integrated specific volume activities in air of each of the radionuclides 218Po, 214Pb, 214Bi, 212Pb, and 212Bi. The method employs thermoluminescence detectors positioned around uniformly rotating filters. Two prototypes that are suitable for practical applications are described and mathematical expressions for data processing are given. Experiments with these "rotating filter dosimeters" were conducted in atmospheres radiologically dominated by 222Rn progeny. The comparison between the results obtained by the proposed method and those given by simultaneously conducted series of instantaneous grab-sampling measurements support the conclusion that the method works for 222Rn progeny. The method can be experimentally extended for 220Rn progeny as well as for unattached fractions. PMID:8387983

Pressyanov, D S; Guelev, M G; Pentchev, O J

1993-05-01

114

Electromagnetic moment investigation of two short-lived isomeric states in118Sb  

NASA Astrophysics Data System (ADS)

Two short-lived isomeric states in118Sb have been investigated by the118Sn( p, n),118Sn( d, 2n) and115In( ?, n) reactions. The TDPAD method on solid and liquid metallic targets was used to measure the electromagnetic moments of these states. The results of the experiments are: 10050_2005_Article_BF01411861_TeX2GIFE1.gif begin{gathered} T_{1/2} = 13.4{text{ }}(3){text{ }}ns I^? = 3^ - {text{ }}g = - 1.254(31){text{ }}|Q| = 0.25{text{ }}(5){text{ }}b, \\ T_{1/2} = 22.8{text{ }}(4){text{ }}ns I^? = 7^ + {text{ }}g = + 0.680(18){text{ }}|Q| > 1.4{text{ }}b. \\ Pure[? 2d_{5/2} ? v1h_{1{text{ }}1/2} ]_{3 - } and[? 1g_{9/2}^{ - 1} ? v2d_{5/2}^{ - 1} ]_{7 + } configurations have been established for the two isomeric states. An experimental evidence concerning the participation of the 1 g {9/2/-1} proton shell-model intruder excitation into the positive parity low-lying level structure of the odd-odd118Sb nucleus was obtained.

Dima, S.; Duma, M.; Ionescu-Bujor, M.; Iord?chescu, A.; Pascovici, G.; Stan-Sion, C.

1985-12-01

115

Short-lived effects of a visual inducer during egocentric space perception and manual behavior.  

PubMed

A pitched visual inducer has a strong effect on the visually perceived elevation of a target in extrapersonal space, and also on the elevation of the arm when a subject points with an unseen arm to the target's elevation. The manual effect is a systematic function of hand-to-body distance (Li and Matin Vision Research 45:533-550, 2005): When the arm is fully extended, manual responses to perceptually mislocalized luminous targets are veridical; when the arm is close to the body, gross matching errors occur. In the present experiments, we measured this hand-to-body distance effect during the presence of a pitched visual inducer and after inducer offset, using three values of hand-to-body distance (0, 40, and 70cm) and two open-loop tasks (pointing to the perceived elevation of a target at true eye level and setting the height of the arm to match the elevation). We also measured manual behavior when subjects were instructed to point horizontally under induction and after inducer offset (no visual target at any time). In all cases, the hand-to-body distance effect disappeared shortly after inducer offset. We suggest that the rapid disappearance of the distance effect is a manifestation of processes in the dorsal visual stream that are involved in updating short-lived representations of the arm in egocentric visual perception and manual behavior. PMID:23653410

Li, Wenxun; Matin, Ethel; Matin, Leonard

2013-07-01

116

Prospect for Using Charge-Coupled Devices in Precise Vertex Detectors for Short-Lived Particle Decays.  

National Technical Information Service (NTIS)

Versions of the vertex detector (VD) with charge coupling devices (CCD) are considered. VD basic characteristics are given. The experimental data on CCD show that VD With CCD is a promising device for experiments on short-lived particles with r < or appro...

S. V. Golovkin V. I. Rykalin

1984-01-01

117

Technical Note: Ensuring consistent, global measurements of short-lived halocarbon gases in the ocean and atmosphere  

Microsoft Academic Search

Short-lived halocarbons are significant sources of reactive halogen in the troposphere and likely the lower stratosphere. Quantifying ambient concentrations in the surface ocean and atmosphere is essential for understanding the impact of fluxes of these gases on marine boundary layer oxidation and lower stratospheric ozone-depletion processes. Despite the body of literature increasing substantially over recent years, calibration issues complicate comparison

J. H. Butler; T. G. Bell; B. D. Hall; B. Quack; L. J. Carpenter; J. Williams

2009-01-01

118

Technical Note: Ensuring consistent, global measurements of very short-lived halocarbon gases in the ocean and atmosphere  

Microsoft Academic Search

Very short-lived halocarbons are significant sources of reactive halogen in the marine boundary layer, and likely in the upper troposphere and lower stratosphere. Quantifying ambient concentrations in the surface ocean and atmosphere is essential for understanding the atmospheric impact of these trace gas fluxes. Despite the body of literature increasing substantially over recent years, calibration issues complicate the comparison of

J. H. Butler; T. G. Bell; B. D. Hall; B. Quack; L. J. Carpenter; J. Williams

2010-01-01

119

Technical Note: Ensuring consistent, global measurements of very short-lived halocarbon gases in the ocean and atmosphere  

Microsoft Academic Search

Very short-lived halocarbons are significant sources of reactive halogen in the marine boundary layer, and likely in the upper troposphere and lower stratosphere. Quantifying ambient concentrations in the surface ocean and atmosphere is essential for understanding the atmospheric impact of these trace gas fluxes. Despite the body of liter- ature increasing substantially over recent years, calibration issues complicate the comparison

J. H. Butler; T. G. Bell; B. D. Hall; B. Quack; L. J. Carpenter; J. Williams

2010-01-01

120

Automated system for neutron activation analysis determination of short lived isotopes at The DOW Chemical Company's TRIGA research reactor  

Microsoft Academic Search

An automated neutron activation analysis (NAA) system for the determination of short lived isotopes was constructed at The DOW Chemical Company's TRIGA Research Reactor in 1993. The NAA group of the Analytical Sciences Laboratory uses the reactor for thousands of analyses each year and therefore automation is important to achieve and maintain high throughput and precision (productivity). This project is

J. J. Zieman; W. L. Rigot; J. D. Romick; T. J. Quinn; C. W. Kocher

1994-01-01

121

Nuclear Moments and Differences in Mean Square Charge Radii of Short-Lived Neon Isotopes by Collinear Laser Spectroscopy  

Microsoft Academic Search

The nuclear moments and charge radii of short-lived neon isotopes were measured by the use of collinear laser spectroscopy at the on-line mass separator ISOLDE at CERN. After a general introduction the semiclassical theory of atomic spectra is given and the relevant properties are calculated for neon. The atomic physics section is followed by a description of the experimental setup

R W Geithner; R Neugart

2002-01-01

122

Thyroid Cancer in the Marshallese: Relative Risk of Short-Lived Internal Emitters and External Radiation Exposure.  

National Technical Information Service (NTIS)

In a study of the comparative effects of internal versus external irradiation of the thyroid in young people, we determined that the dose from internal irradiation of the thyroid with short-lived internal emitters produced several times less thyroid cance...

E. T. Lessard A. B. Brill W. H. Adams

1985-01-01

123

ACTIVE MEDIA. RESONATORS: Short-lived absorption in excited gadolinium scandium gallium garnet crystals activated with Cr and Nd  

Microsoft Academic Search

An analysis is made of the possibility of reducing short-lived losses in a gadolinium scandium gallium garnet crystal activated with Cr and Nd when these losses are due to the short-wavelength component of the spectrum of the exciting radiation.

Evgeny V. Zharikov; S. P. Nasel'skii; A. I. Ryabov; Ivan A. Shcherbakov

1987-01-01

124

Measurement of number and size distribution of particles emitted from a mid-sized transportation multipoint port fuel injection gasoline engine  

Microsoft Academic Search

This study was carried out to characterize the engine-exhaust particulate emissions from a typical multipoint port fuel injection gasoline engine used in transportation sector. Though gasoline engine showed no visible tail pipe emissions yet its particle concentrations were comparable to mineral diesel, particularly at high engine loads. Average sizes of particles emitted in gasoline exhaust are found to be way

Tarun Gupta; Abhishek Kothari; Dhananjay Kumar Srivastava; Avinash Kumar Agarwal

2010-01-01

125

Short-Lived Effector CD8 T Cells Induced by Genetically Attenuated Malaria Parasite Vaccination Express CD11c.  

PubMed

Vaccination with a single dose of genetically attenuated malaria parasites can induce sterile protection against sporozoite challenge in the rodent Plasmodium yoelii model. Protection is dependent on CD8(+) T cells, involves perforin and gamma interferon (IFN-?), and is correlated with the expansion of effector memory CD8(+) T cells in the liver. Here, we have further characterized vaccine-induced changes in the CD8(+) T cell phenotype and demonstrated significant upregulation of CD11c on CD3(+) CD8b(+) T cells in the liver, spleen, and peripheral blood. CD11c(+) CD8(+) T cells are predominantly CD11a(hi) CD44(hi) CD62L(-), indicative of antigen-experienced effector cells. Following in vitro restimulation with malaria-infected hepatocytes, CD11c(+) CD8(+) T cells expressed inflammatory cytokines and cytotoxicity markers, including IFN-?, tumor necrosis factor alpha (TNF-?), interleukin-2 (IL-2), perforin, and CD107a. CD11c(-) CD8(+) T cells, on the other hand, expressed negligible amounts of all inflammatory cytokines and cytotoxicity markers tested, indicating that CD11c marks multifunctional effector CD8(+) T cells. Coculture of CD11c(+), but not CD11c(-), CD8(+) T cells with sporozoite-infected primary hepatocytes significantly inhibited liver-stage parasite development. Tetramer staining for the immunodominant circumsporozoite protein (CSP)-specific CD8(+) T cell epitope demonstrated that approximately two-thirds of CSP-specific cells expressed CD11c at the peak of the CD11c(+) CD8(+) T cell response, but CD11c expression was lost as the CD8(+) T cells entered the memory phase. Further analyses showed that CD11c(+) CD8(+) T cells are primarily KLRG1(+) CD127(-) terminal effectors, whereas all KLRG1(-) CD127(+) memory precursor effector cells are CD11c(-) CD8(+) T cells. Together, these results suggest that CD11c marks a subset of highly inflammatory, short-lived, antigen-specific effector cells, which may play an important role in eliminating infected hepatocytes. PMID:23980113

Cooney, Laura A; Gupta, Megha; Thomas, Sunil; Mikolajczak, Sebastian; Choi, Kimberly Y; Gibson, Claire; Jang, Ihn K; Danziger, Sam; Aitchison, John; Gardner, Malcolm J; Kappe, Stefan H I; Wang, Ruobing

2013-08-26

126

Polyhalogenated Very Short Live Substances in the Atlantic Ocean, and their Linkages with Ocean Primary Production  

NASA Astrophysics Data System (ADS)

The Halocarbon Air-Sea Transect - Atlantic (HalocAST-A) cruise was conducted aboard FS Polarstern during the ANT-XXVII/1 expedition. The ship departed from Bremerhaven, Germany on October 25th and arrived in Cape Town, South Africa on November 24th in 2010. The HalocAST-A cruise was devoted to studying air-sea fluxes of a suite of halocarbon compounds. Atmospheric mixing ratios and seawater concentrations of the halocarbons were continuously measured with the gas chromatograph - mass spectrometer (GC-MS). This study focuses on the polyhalogenated very short lived substances (VSLSs) such as bromoform (CHBr3), dibromomethane (CH2Br2), chlorodibromomethane (CHClBr2), and bromodichloromethane (CHBrCl2). The goal of this study is to examine the distributions of these compounds and possible relationship between their emissions and oceanic primary production. Therefore, along with the halocarbon concentrations, parameters like dissolved organic carbon concentrations, nutrient concentrations, pigment concentrations, and picoplankton and heterotrophic bacteria counts were also determined. The observed saturation anomalies indicated these VSLSs were supersaturated for almost the entire duration of the cruise. The highest seawater concentrations for these compounds were observed near the Canary Islands. Air mixing ratios were also elevated in this region. The net fluxes for CHBr3, CH2Br2, CHClBr2, and CHBrCl2 were 13.8 nmol m-2 d-1, 4.5 nmol m-2 d-1, 4.5 nmol m-2 d-1 and 1.2 nmol m-2 d-1, respectively. During the HalocAST-A cruise, these compounds exhibit similar trends with total chlorophyll a. Contributions from selected phytoplankton group will be further assessed through the use of individual pigment biomarkers.

Liu, Y.; Yvon-Lewis, S. A.; Hu, L.; Bianchi, T. S.; Campbell, L.; Smith, R. W.

2011-12-01

127

Longitudinal analysis of Plantago: adaptive benefits of iteroparity in a short-lived, herbaceous perennial  

PubMed Central

Theory suggests that iteroparity may confer greater fitness than semelparity in situations in which temporal environmental variation is high and unpredictable. Variable age-specific mortality, density dependence, and other factors may also favor iteroparity over semelparity. Here, we empirically test the adaptive benefits of greater numbers of reproductive years in a study of reproductive schedules in an experimental population of a short-lived polycarpic perennial, Plantago lanceolata. A large experimental population was established that included four cohorts with similar genetic structure. Individuals were censused for mortality, size, and reproduction for seven years. Plants experienced variable numbers of reproductive years, but one or two years were most common (~46.7% of the population reproduced only once). The probability of flowering at least once prior to death was determined strongly by extrinsic, environmental or intrinsic but environmentally influenced variables, including early-life size, cohort, and block, but also varied with a number of interactions involving paternal lineage. Maternal effects explained small but significant components of the variance in the number of reproductive years among individuals in each cohort, while paternal effects were significant in only two cohorts. Number of reproductive years contributed significantly to fitness in this system, more so than all other variables tested, although most of the variation in relative fitness may be attributed ultimately to environmental influences. We suggest that the high proportion of each cohort composed of plants reproducing only once may be due to environmental constraints on either growth or size. Such environmental influences, particularly on early life size, may result in small but important indirect effects on fitness.

Shefferson, Richard P.; Roach, Deborah A.

2010-01-01

128

Short-lived radioactivity in the early solar system: The Super-AGB star hypothesis  

NASA Astrophysics Data System (ADS)

The composition of the most primitive solar system condensates, such as calcium-aluminum-rich inclusions (CAIs) and micron-sized corundum grains, show that short-lived radionuclides (SLR), e.g., 26Al, were present in the early solar system. Their abundances require a local or stellar origin, which, however, is far from being understood. We present for the first time the abundances of several SLR up to 60Fe predicted from stars with initial mass in the range approximately 7-11 M?. These stars evolve through core H, He, and C burning. After core C burning they go through a "Super"-asymptotic giant branch (Super-AGB) phase, with the H and He shells activated alternately, episodic thermal pulses in the He shell, a very hot temperature at the base of the convective envelope (approximately 108 K), and strong stellar winds driving the H-rich envelope into the surrounding interstellar medium. The final remnants of the evolution of Super-AGB stars are mostly O-Ne white dwarfs. Our Super-AGB models produce 26Al/27Al yield ratios approximately 0.02-0.26. These models can account for the canonical value of the 26Al/27Al ratio using dilutions with the solar nebula of the order of 1 part of Super-AGB mass per several 102 to several 103 of solar nebula mass, resulting in associated changes in the O-isotope composition in the range ?17O from 3 to 20. This is in agreement with observations of the O isotopic ratios in primitive solar system condensates, which do not carry the signature of a stellar polluter. The radionuclides 41Ca and 60Fe are produced by neutron captures in Super-AGB stars and their meteoritic abundances are also matched by some of our models, depending on the nuclear and stellar physics uncertainties as well as the meteoritic experimental data. We also expect and are currently investigating Super-AGB production of SLR heavier than iron, such as 107Pd.

Lugaro, Maria; Doherty, Carolyn L.; Karakas, Amanda I.; Maddison, Sarah T.; Liffman, Kurt; Garca-Hernndez, D. A.; Siess, Lionel; Lattanzio, John C.

2012-12-01

129

Solar system genealogy revealed by extinct short-lived radionuclides in meteorites  

NASA Astrophysics Data System (ADS)

Context. Little is known about the stellar environment and the genealogy of our solar system. Short-lived radionuclides (SLRs, mean lifetime ? shorter than 100 Myr) that were present in the solar protoplanetary disk 4.56 Gyr ago could potentially provide insight into that key aspect of our history, were their origin understood. Aims: Previous models failed to provide a reasonable explanation of the abundance of two key SLRs, 26Al (?26 = 1.1 Myr) and 60Fe (?60 = 3.7 Myr), at the birth of the solar system by requiring unlikely astrophysical conditions. Our aim is to propose a coherent and generic solution based on the most recent understanding of star-forming mechanisms. Methods: Iron-60 in the nascent solar system is shown to have been produced by a diversity of supernovae belonging to a first generation of stars in a giant molecular cloud. Aluminum-26 is delivered into a dense collected shell by a single massive star wind belonging to a second star generation. The Sun formed in the collected shell as part of a third stellar generation. Aluminum-26 yields used in our calculation are based on new rotating stellar models in which 26Al is present in stellar winds during the star main sequence rather than during the Wolf-Rayet phase alone. Our scenario eventually constrains the time sequence of the formation of the two stellar generations that just preceded the solar system formation, along with the number of stars born in these two generations. Results: We propose a generic explanation for the past presence of SLRs in the nascent solar system, based on a collect-injection-and-collapse mechanism, occurring on a diversity of spatial/temporal scales. In that model, the presence of SLRs with a diversity of mean lifetimes in the solar protoplanetary disk is simply the fossilized record of sequential star formation within a hierarchical interstellar medium. We identify the genealogy of our solar system's three star generations earlier. In particular, we show that our Sun was born together with a few hundred stars in a dense collected shell situated at a distance of 5-10 pc from a parent massive star having a mass greater than about 30 solar masses and belonging to a cluster containing ~1200 stars.

Gounelle, M.; Meynet, G.

2012-09-01

130

Results of the 2010 National Radiation Protection Institute intercomparison of radon and its short-lived decay product continuous monitors.  

PubMed

During the Sixth European Conference on Protection Against Radon at Home and at Work held in autumn 2010 in Prague, the first intercomparison of continuous radon and its short-lived decay product monitors was organised and held by the Natural Radiation Division of the National Radiation Protection Institute (NRPI) in Prague. Eight laboratories submitted eight continuous radon monitors, two electronic monitors, three passive integral systems based on charcoal and three continuous radon short-lived decay product monitors. The intercomparison included exposures to both the radon gas concentration and equivalent equilibrium radon concentration (EEC) under different ambient conditions similar to the ones in dwellings. In particular, the influence of the equilibrium factor F, unattached fraction of EEC f(p) and absolute air humidity were investigated. The results of the radon gas measurements were performed on a calibration level of about 8 kBq m(-3). The results of all monitors were compared with the reference NRPI monitor. PMID:21471124

Jlek, K; Maruiakov, M

2011-04-06

131

Large-Scale Mass Measurements of Short-Lived Nuclides with the Isochronous Mass Spectrometry at GSI  

NASA Astrophysics Data System (ADS)

Precise mass measurements of short-lived exotic nuclei are very important for the understanding of basic nuclear structure physics and astrophysical nucleosynthesis in nature, as well as for the test and the development of theoretical nuclear mass models. At GSI, the Isochronous Mass Spectrometry (IMS) dedicated to mass measurements of short-lived nuclides was developed. In this contribution, the IMS technique is briefly reviewed. Recently, the first large-scale measurement on the 238U fission fragment was done successfully. The measured mass values are in excellent agreement with the recent Penning trap data, however, they show a systematical deviation from the values in the latest atomic mass evaluation. Some representative results from this experiment will be presented, including their impact on nuclear structure physics and astrophysical r-process nucleosynthesis.

Sun, B.; Knbel, R.; Litvinov, Yu. A.; Nakajima, S.; Geissel, H.; Meng, J.; Beckert, K.; Bosch, F.; Boutin, D.; Brandau, C.; Chen, L.; Cullen, I. J.; Dimopoulou, C.; Fabian, B.; Hausmann, M.; Klepper, O.; Kozhuharov, C.; Kurcewicz, J.; Litvinov, S. A.; Mazzocco, M.; Montes, F.; Mnzenberg, G.; Musumarra, A.; Nociforo, C.; Nolden, F.; Ohtsubo, T.; Ozawa, A.; Patyk, Z.; Pla, W. R.; Scheidenberger, C.; Steck, M.; Suzuki, T.; Walker, P. M.; Weick, H.; Winckler, N.; Winkler, M.; Yamaguchi, T.

132

Half-lives of some short-lived mass-separated gaseous fission products and their daughters  

Microsoft Academic Search

The half-lives of several short-lived isotopes of Kr, Rb, Sr, Xe, Cs and Ba have been measured using sources of isotopically pure Xe or Kr and multi-scaling selected transitions in the Ge(Li) gamma-ray spectra of their decays. Beta-ray multi-scaling was employed to confirm the gamma-ray multi-scaling results in several cases. The results of the measurements are (in sec) 89Kr, 190.7+\\/-1.4

G. C. Carlson; W. C. Schick; W. L. Talbert; F. K. Wohn

1969-01-01

133

Asymptotic Giant Branch stars as a source of short-lived radioactive nuclei in the solar nebula  

Microsoft Academic Search

We carried out a theoretical evaluation of the contribution of Asymptotic Giant Branch (AGB) stars to some short-lived (106 less than or equal to Tau-bar less than or equal to 2 x 107 yr) isotopes in the Interstellar Medium (ISM) and in the early solar system using stellar model calculations for thermally pulsing evolutionary phases of low-mass stars. The yields

G. J. Wasserburg; M. Busso; R. Gallino; C. M. Raiteri

1994-01-01

134

Cross Sections Needed for the Interpretation of Long-Lived and Short-Lived Cosmogenic Nuclide Production in Extraterrestrial Materials  

Microsoft Academic Search

Radionuclides produced by cosmic rays in extraterrestrial materials archive information that can be used to determine cosmic-ray fluxes and to study the history of the irradiated object. Long-lived radionuclides give information about the last ~5 Myr; short-lived radionuclides give information about recent events. To calculate the solar cosmic ray (SCR) flux from measured depth profiles for cosmogenic radionuclides produced in

J. M. Sisterson; A. Beverding; K. J. Kim; P. A. J. Englert; A. J. T. Jull; D. J. Donahue; S. Cloudt; C. Castaneda; J. Vincent; M. W. Caffee; C. O. Osazuwa; R. C. Reedy

1995-01-01

135

Age-specific, density-dependent and environment-based mortality of a short-lived perennial herb  

Microsoft Academic Search

Density-independent and density-dependent processes affect plant mortality. Although less well understood, age-specific mortality can also play an important role in plant mortality. The goal of this study was to analyse sev- eral factors accounting for mortality in the Mediterranean short-lived peren- nial herb Lobularia maritima. We followed three cohorts of plants (from emergence to death) during 4 years in field

F. X. Pico ; J. Retana

2008-01-01

136

Measurement method of activation cross-sections of reactions producing short-lived nuclei with 14 MeV neutrons  

Microsoft Academic Search

We describe a method for obtaining reliable activation cross-sections in the neutron energy range between 13.4 and 14.9MeV for the reactions producing short-lived nuclei with half-lives between 0.5 and 30min. We noted neutron irradiation fields and measured induced activities, including (1) the contribution of scattered low-energy neutrons, (2) the fluctuation of the neutron fluence rate during the irradiation, (3) the

K. Kawade; H. Sakane; Y. Kasugai; M. Shibata; T. Iida; A. Takahashi; T. Fukahori

2003-01-01

137

An activation analysis system for short-lived radioisotopes including automatic dead-time corrections with a microcomputer  

Microsoft Academic Search

A system based on an IBM-PC microcomputer coupled to a Canberra Series 80 multichannel analyser has been developed for activation analysis with short-lived radioisotopes. The data transfer program can store up to 77 gamma-ray spectra on a floppy disk. A spectrum analysis program, DVC, has been written to determine peak areas interactively, to correct the counting losses, and to calculate

G. Kennedy; J. Marcotte; L. Zikovsky

1987-01-01

138

Proline-rich tyrosine kinase-2 is critical for CD8 T-cell short-lived effector fate  

PubMed Central

T-cell interactions with antigen-presenting cells are important for CD8 T-cell effector or memory fate determination. The integrin leukocyte function-associated antigen-1 (LFA-1) mediates T-cell adhesion but the contribution of LFA-1induced signaling pathways to T-cell responses is poorly understood. Here we demonstrate that proline-rich tyrosine kinase-2 (PYK2) deficiency impairs CD8 T-cell activation by synergistic LFA-1 and T-cell receptor stimulation. Furthermore, PYK2 is essential for LFA-1-mediated CD8 T-cell adhesion and LFA-1 costimulation of CD8 T-cell migration. During lymphocytic choriomeningitis virus infection in vivo, PYK2 deficiency results in a specific loss of short-lived effector CD8 T cells but does not affect memory-precursor CD8 T-cell development. Similarly, lack of LFA-1 primarily impairs the generation of short-lived effector cells. Thus, PYK2 facilitates LFA-1dependent CD8 T-cell responses and promotes CD8 T-cell short-lived effector fate, suggesting that PYK2 may be an interesting therapeutic target to suppress exacerbated CD8 T-cell responses.

Beinke, Soren; Phee, Hyewon; Clingan, Jonathan M.; Schlessinger, Joseph; Matloubian, Mehrdad; Weiss, Arthur

2010-01-01

139

Short-lived and long-lived dust devil tracks in the coastal desert of southern Peru  

NASA Astrophysics Data System (ADS)

In the coastal desert of southern Peru, sequential high-resolution satellite images document the presence of short-lived and long-lived dust devil tracks. Dust devil tracks in the study region remain visible for less than 6 months in one area and for more than 4 years in another area. Short-lived tracks are generally darker than the surrounding ground surface. The brightness of long-lived tracks is often equal to that of their surroundings; they become visible due to a brighter edge along their margins. Different modes of formation related to ground surface properties are suggested to explain the differences in persistence and appearance. Dark, short-lived dust devil tracks are ascribed to the removal of silt-sized material from largely sand-sized surface materials. Long-lived tracks with bright margins are ascribed to coarser surface materials and the fallout of sand-sized particles along the track edges. Locating suitable areas on Earth for the study of dust devil tracks and distinguishing between different types of dust devil tracks is expected to further promote terrestrial analogue studies for Martian dust devil streaks.

Hesse, Ralf

2012-08-01

140

Identification of short-lived long non-coding RNAs as surrogate indicators for chemical stress response.  

PubMed

Abiotic and biotic stressors in human cells are often a result of sudden and/or frequent changes in environmental factors. The molecular response to stress involves elaborate modulation of gene expression and is of homeostatic, ecological, and evolutionary importance. Although attention has primarily focused on signaling pathways and protein networks, long non-coding RNAs (ncRNAs) are increasingly involved in the molecular mechanisms associated with responses to cellular stresses. We identified six novel short-lived long ncRNAs (MIR22HG, GABPB-AS1, LINC00152, IDI2-AS1, SNHG15, and FLJ33630) that responded to chemical stressors (cisplatin, cycloheximide, and mercury (II) oxide) in HeLa Tet-off cells. Our results indicate that short-lived long ncRNAs respond to general and specific chemical stressors. The expression levels of the short-lived long ncRNAs were elevated because of prolonged decay rates in response to chemical stressors and interruption of RNA degradation pathways. We propose that these long ncRNAs have the potential to be surrogate indicators of cellular stress responses. PMID:24036268

Tani, Hidenori; Torimura, Masaki

2013-09-10

141

Treatment of HER2 Positive Breast Carcinomatous Meningitis with Intrathecal Administration of ?-Particle Emitting 211At-labeled Trastuzumab?  

PubMed Central

Introduction Carcinomatous meningitis (CM) is a devastating disease characterized by the dissemination of malignant tumor cells into the subarachnoid space along the brain and spine. Systemic treatment with monoclonal antibody (mAb) trastuzumab can be effective against HER2-positive systemic breast carcinoma but like other therapies, is ineffective against CM. The goal of this study was to evaluate the therapeutic effect of ?-particle emitting 211At-labeled trastuzumab following intrathecal administration in a rat model of breast carcinoma CM. Methods Athymic rats were injected intrathecally with MCF-7/HER2-18 breast carcinoma cells through a surgically-implanted indwelling intrathecal catheter. In Experiment 1, animals received 33 or 66 Ci 211At-labeled trastuzumab, cold trastuzumab, or saline. In Experiment 2, animals were inoculated with a lower tumor burden and received 46 or 92 Ci 211At-labeled trastuzumab, or saline. In Experiment 3, animals received 28 Ci 211At-labeled trastuzumab, 30 Ci 211At-labeled TPS3.2 control mAb or saline. Histopathological analysis of the neuroaxis was performed at the end of the study. Results In Experiment 1, median survival increased from 21 days for the saline and cold trastuzumab groups to 45 and 48 days for 33 and 66 Ci 211At-labeled trastuzumab, respectively. In Experiment 2, median survival increased from 23 days for saline controls to 68 and 92 days for 46 and 92 Ci 211At-labeled trastuzumab, respectively. In Experiment 3, median survival increased from 20 days to 29 and 36 days for animals treated with 211At-labeled TPS3.2 and 211At-labeled trastuzumab, respectively. Long-term survivors were observed exclusively in the 211At-trastuzumab-treated groups. Conclusion Intrathecal 211At-labeled trastuzumab shows promise as a treatment for patients with HER2-positive breast CM.

Boskovitz, Abraham; McLendon, Roger E.; Okamura, Tatsunori; Sampson, John H.; Bigner, Darell D.; Zalutsky, Michael R.

2009-01-01

142

ENGINEERED MODULAR RECOMBINANT TRANSPORTERS: APPLICATION OF NEW PLATFORM FOR TARGETED RADIOTHERAPEUTIC AGENTS TO ?-PARTICLE EMITTING 211At  

PubMed Central

Purpose To generate and evaluate a modular recombinant transporter (MRT) for targeting 211At to cancer cells overexpressing the epidermal growth factor receptor (EGFR). Methods and Materials The MRT was produced with four functional modules: (1) human epidermal growth factor as the internalizable ligand, (2) the optimized nuclear localization sequence of simian vacuolating virus 40 (SV40) large T-antigen, (3) a translocation domain of diphtheria toxin as an endosomolytic module, and (4) the Escherichia coli hemoglobin-like protein (HMP) as a carrier module. MRT was labeled using N-succinimidyl 3-[211At]astato-5-guanidinomethylbenzoate (SAGMB), its 125I analogue SGMIB, or with 131I using Iodogen. Binding, internalization, and clonogenic assays were performed with EGFR-expressing A431, D247 MG, and U87MG.wtEGFR human cancer cell lines. Results The affinity of SGMIB-MRT binding to A431 cells, determined by Scatchard analysis, was 22 nM, comparable to that measured before labeling. The binding of SGMIB-MRT and its internalization by A431 cancer cells was 96% and 99% EGFR specific, respectively. Paired label assays demonstrated that compared with Iodogen-labeled MRT, SGMIB-MRT and SAGMB-MRT exhibited more than threefold greater peak levels and durations of intracellular retention of activity. SAGMB-MRT was 1020 times more cytotoxic than [211At]astatide for all three cell lines. Conclusion The results of this study have demonstrated the initial proof of principle for the MRT approach for designing targeted ?-particle emitting radiotherapeutic agents. The high cytotoxicity of SAGMB-MRT for cancer cells overexpressing EGFR suggests that this 211At-labeled conjugate has promise for the treatment of malignancies, such as glioma, which overexpress this receptor.

Rosenkranz, Andrey A.; Vaidyanathan, Ganesan; Pozzi, Oscar R.; Lunin, Vladimir G.; Zalutsky, Michael R.; Sobolev, Alexander S.

2010-01-01

143

VLA Observations Confirm Origin of Gamma Ray Bursts in Short-Lived Stars  

NASA Astrophysics Data System (ADS)

Radio telescope studies of the fiery afterglow of a Gamma Ray Burst have provided astronomers with the best clues yet about the origins of these tremendous cosmic cataclysms since their discovery more than 30 years ago. Observations with the National Science Foundation's (NSF) Very Large Array (VLA) radio telescope confirm that a blast seen to occur on March 29 had its origin in a star-forming region in a distant galaxy. "There are two leading theories for the causes of Gamma Ray Bursts," said Dale Frail of the NSF National Radio Astronomy Observatory (NRAO) in Socorro, NM. "According to one theory, the blasts occur in the death throes of pairs of old stars. The other requires them to arise from exploding, massive, short-lived stars that still reside within the star-forming gas and dust from which they formed. The VLA studies of the burst show that at least this one almost certainly occurred within a star-forming region. This result also explains why half of the Gamma Ray Burst afterglows are not detected by optical telescopes." Frail heads a VLA observing team including Greg Taylor, also of NRAO, and Shri Kulkarni of Caltech, that reported its findings to the American Astronomical Society meeting in San Diego, CA. The March 29 burst was seen clearly by radio telescopes (the accompanying image is GRB 980329 as seen by the VLA) but only very faintly with optical instruments. "That is extremely important," said Taylor. "This burst was very faint at visible wavelengths, brighter at infrared wavelengths and brighter still at radio wavelengths. This is a clear indication that the exploding object was surrounded by dust. Dust is most commonly found in star-forming regions." This strongly favors one of the two leading theories about Gamma Ray Bursts over the other. One explanation for these tremendously energetic fireballs is that a pair of superdense neutron stars collides. The other is that a single, very massive star explodes in a "hypernova," more powerful than a supernova, at the end of its normal life. The hypernova explosion, scientists believe, would come only a few million years after the giant star was formed, while it is still within the cloud of gas and dust from which it formed. Neutron stars, on the other hand, are formed by supernova explosions that give a "kick" to the resulting neutron star, propelling it at high speeds. An orbiting pair of neutron stars, astronomers think, would collide only after hundreds of millions of years of orbital decay, by which time they would be far away from the gas and dust of their birthplace. "The observations already have provided crucial insight; we intend to continue observing the relic of the March 29 burst with the VLA, and in the coming months, we will gain new information that will help further refine our ideas about these fireballs," Frail said. "We're going to learn about the size and expansion rate of the fireball and test predictions made by the models." "These observations indicate the extraordinary importance of radio astronomy for providing information that can be gained in no other way about one of the major frontier areas of astrophysics," said Hugh Van Horn, Director of the NSF's Division of Astronomical Sciences. The March 29 burst (GRB 980329) was the second such blast to have its afterglow detected at radio wavelengths. Last year, the VLA made the first radio detection of a GRB afterglow, finding radio emission coming from the location of a Gamma Ray Burst on May 8, 1997 (GRB 970508). "Of the world's radio telescopes, only the VLA has the sensitivity and resolving power to quickly detect these radio afterglows of Gamma Ray Bursts and study them in detail over extended periods of time," Taylor said. "Even so, we only see the brightest one-third of them. With upgraded capabilities at the VLA, as planned by NRAO, we will see them all." The National Radio Astronomy Observatory is a facility of the National Science Foundation, operated under cooperative agr

1998-06-01

144

Genome-wide determination of RNA stability reveals hundreds of short-lived noncoding transcripts in mammals  

PubMed Central

Mammalian genomes produce huge numbers of noncoding RNAs (ncRNAs). However, the functions of most ncRNAs are unclear, and novel techniques that can distinguish functional ncRNAs are needed. Studies of mRNAs have revealed that the half-life of each mRNA is closely related to its physiological function, raising the possibility that the RNA stability of an ncRNA reflects its function. In this study, we first determined the half-lives of 11,052 mRNAs and 1418 ncRNAs in HeLa Tet-off (TO) cells by developing a novel genome-wide method, which we named 5?-bromo-uridine immunoprecipitation chasedeep sequencing analysis (BRIC-seq). This method involved pulse-labeling endogenous RNAs with 5?-bromo-uridine and measuring the ongoing decrease in RNA levels over time using multifaceted deep sequencing. By analyzing the relationship between RNA half-lives and functional categories, we found that RNAs with a long half-life (t1/2 ? 4 h) contained a significant proportion of ncRNAs, as well as mRNAs involved in housekeeping functions, whereas RNAs with a short half-life (t1/2 < 4 h) included known regulatory ncRNAs and regulatory mRNAs. The stabilities of a significant set of short-lived ncRNAs are regulated by external stimuli, such as retinoic acid treatment. In particular, we identified and characterized several novel long ncRNAs involved in cell proliferation from the group of short-lived ncRNAs. We designated this novel class of ncRNAs with a short half-life as Short-Lived noncoding Transcripts (SLiTs). We propose that the strategy of monitoring RNA half-life will provide a powerful tool for investigating hitherto functionally uncharacterized regulatory RNAs.

Tani, Hidenori; Mizutani, Rena; Salam, Kazi Abdus; Tano, Keiko; Ijiri, Kenichi; Wakamatsu, Ai; Isogai, Takao; Suzuki, Yutaka; Akimitsu, Nobuyoshi

2012-01-01

145

Harvard-MIT research program in short-lived radiopharmaceuticals. Progress report, March 1, 1983-February 29, 1984  

SciTech Connect

This report describes research efforts towards the achievement of a clearer understanding of the solution chemistry of technetium in order to facilitate the design of future clinical agents labeled with Tc-99m, the development of new receptor binding radiopharmaceuticals for the in vivo assessment of insulin receptors and for imaging the adrenal medulla and the brain, the examination of the utility of monoclonal antibodies and liposomes in the design of radiopharmaceuticals for diagnosis and therapy, and the synthesis of short-lived positron-emitting radiopharmaceuticals for transverse imaging of regional physiological processes.

Adelstein, S.J.; Brownell, G.L.

1984-02-01

146

Novel biogenic iodine-containing trihalomethanes and other short-lived halocarbons in the coastal East Atlantic  

Microsoft Academic Search

Reactive halogen photochemistry and its impact on tropospheric oxidant levels have recently attracted intense research interest following the observation of the iodine oxide radical at midlatitudes. During September 1998, short-lived organoiodines including CH3I, C2H5I, CH2ICl, CH2IBr, CH2I2, and the hitherto undetected CHIBr2, as well as the organobromines CHBr3, CH2Br2, CHBr2Cl2, CH3Br, and C2H5Br, were measured in air and seawater at

L. J. Carpenter; G. Malin; P. S. Liss; F. C. Kpper

2000-01-01

147

Impact of preindustrial to present-day changes in short-lived pollutant emissions on atmospheric composition and climate forcing  

NASA Astrophysics Data System (ADS)

We describe and evaluate atmospheric chemistry in the newly developed Geophysical Fluid Dynamics Laboratory chemistry-climate model (GFDL AM3) and apply it to investigate the net impact of preindustrial (PI) to present (PD) changes in short-lived pollutant emissions (ozone precursors, sulfur dioxide, and carbonaceous aerosols) and methane concentration on atmospheric composition and climate forcing. The inclusion of online troposphere-stratosphere interactions, gas-aerosol chemistry, and aerosol-cloud interactions (including direct and indirect aerosol radiative effects) in AM3 enables a more complete representation of interactions among short-lived species, and thus their net climate impact, than was considered in previous climate assessments. The base AM3 simulation, driven with observed sea surface temperature (SST) and sea ice cover (SIC) over the period 1981-2007, generally reproduces the observed mean magnitude, spatial distribution, and seasonal cycle of tropospheric ozone and carbon monoxide. The global mean aerosol optical depth in our base simulation is within 5% of satellite measurements over the 1982-2006 time period. We conduct a pair of simulations in which only the short-lived pollutant emissions and methane concentrations are changed from PI (1860) to PD (2000) levels (i.e., SST, SIC, greenhouse gases, and ozone-depleting substances are held at PD levels). From the PI to PD, we find that changes in short-lived pollutant emissions and methane have caused the tropospheric ozone burden to increase by 39% and the global burdens of sulfate, black carbon, and organic carbon to increase by factors of 3, 2.4, and 1.4, respectively. Tropospheric hydroxyl concentration decreases by 7%, showing that increases in OH sinks (methane, carbon monoxide, nonmethane volatile organic compounds, and sulfur dioxide) dominate over sources (ozone and nitrogen oxides) in the model. Combined changes in tropospheric ozone and aerosols cause a net negative top-of-the-atmosphere radiative forcing perturbation (-1.05 W m-2) indicating that the negative forcing (direct plus indirect) from aerosol changes dominates over the positive forcing due to ozone increases, thus masking nearly half of the PI to PD positive forcing from long-lived greenhouse gases globally, consistent with other current generation chemistry-climate models.

Naik, Vaishali; Horowitz, Larry W.; Fiore, Arlene M.; Ginoux, Paul; Mao, Jingqiu; Aghedo, Adetutu M.; Levy, Hiram

2013-07-01

148

Reduction of short-lived atmospheric pollutant emissions as an alternative strategy for climate-change moderation  

NASA Astrophysics Data System (ADS)

The current state of studies on short-lived atmospheric constituents (greenhouse gases and aerosols) is reviewed. They have short atmospheric lifetimes (from several days to a few years) and can significantly affect the environment and climate. We propose reducing the emissions of these constituents as an alternative to the reduction of man-made carbon dioxide releases. We consider methane, hydrofluorocarbons, tropospheric ozone, and various aerosols (primarily, black carbon); discuss their atmospheric sources and destruction mechanisms; evaluate their content, atmospheric emissions, and climate impacts; and recommend efficient actions for the nearest future.

Karol', I. L.; Kiselev, A. A.; Genikhovich, E. L.; Chicherin, S. S.

2013-09-01

149

Unusual negative photochromism via a short-lived imidazolyl radical of 1,1'-binaphthyl-bridged imidazole dimer.  

PubMed

We have synthesized a new photochromic compound that exhibits unusual negative photochromism, in which the stable colored species photochemically converts into the metastable colorless species via a short-lived radical. This compound has a 1,1'-binaphthyl moiety bridging the two diphenylimidazole units. Its photochemical properties were investigated by nanosecond laser flash photolysis. The colored species isomerizes to the colorless species upon exposure to visible light and thermally returns to the original colored species within 20 min at room temperature. Moreover, the photodecoloration reaction proceeds via a short-lived radical with a half-life of 9.4 ?s in benzene at room temperature. Both the colored and colorless species show the photoinduced homolytic bond cleavage reaction of the C-N bond between the nitrogen atom of the imidazole ring and the carbon atom of the 1-position of the 1,1'-binaphthyl moiety and that of the C-C bond between each of the carbon atoms of the 2-position of the imidazole ring, respectively, followed by their formation by rapid radical coupling. PMID:23402262

Hatano, Sayaka; Horino, Takeru; Tokita, Atsuhiro; Oshima, Toyoji; Abe, Jiro

2013-02-18

150

Overview of the methods for the measurement and interpretation of short-lived radioisotopes and their limits  

NASA Astrophysics Data System (ADS)

The daughter products of the uranium and thorium series consist of several radioactive isotopes with half-lives varying from less than a second to 105 years. Combining their half-live with their geochemical behaviour some of these radioisotopes could be used as tracers and/or chronometers of sedimentary processes. For example, thorium isotopes, and to a lesser extent polonium isotopes are characterized by very low solubility and very high affinity for the surface of particles. Consequently, thorium isotopes can be used to document scavenging and adsorption processes. On the other hand, radium isotopes tend to remain in solution and can be used to document diffusion processes. In the following, we present the analytical methods for the measurement and analysis of the most common short-lived isotopes and throughout their utility in studying sedimentary processes will be illustrated by a few examples of applications. These examples will focus essentially on the applications of short lived thorium isotopes (notably 234Th) and the use of 210Pb as chronometer for recent sedimentary accumulation.

Ghaleb, B.

2009-01-01

151

Short-lived organic trace gases in the UT/LS: Results from recent field campaigns. (Invited)  

NASA Astrophysics Data System (ADS)

Recent research campaigns in the tropics (TC-4 and AVE missions) and in the extra-tropics (START08) have included the measurement of trace gases from whole air sampling on the NASA WB-57 or NSF Gulfstream V aircraft. Measurements of a range of halocarbons, hydrocarbons, organic nitrates, and sulfur species were made during these missions to examine the role of short-lived organic gases in the UT/LS. The trace gas composition of the upper troposphere/lower stratosphere (UT/LS) region depends on emission sources, transport pathways, mixing rates and photochemical processing time. Because surface emissions include gases with a range of chemical lifetimes, and because different source emissions (e.g. marine boundary layer, anthropogenic emissions, biomass burning) can have different chemical signatures, the composition of the organic trace gases that are found in the UT/LS region have the potential to provide diagnostic information on air mass sources and transport time scales. Also, measurement of short-lived organic halogen gases in the UT/LS during these missions provides data to define the reactive halogen budget and the chemical boundary conditions for the stratospheric chemistry that affects ozone depletion rates. This presentation will highlight different aspects of these measurements that deal with transport pathways, transport rates, and halogen budgets.

Atlas, E. L.; Pan, L.; Schauffler, S.; Bowman, K. P.; Blake, D. R.; Meinardi, S.; Stone, D.; Lueb, R.; Zhu, X.; Pope, L.

2009-12-01

152

Production cross sections of short-lived silver radionuclides from natPd(p,xn) nuclear processes  

NASA Astrophysics Data System (ADS)

Production cross-sections of short-lived 103Ag, 104mAg and 104gAg radionuclides from proton-induced reactions on natural palladium (Pd) were measured up to 41 MeV by using a stacked-foil activation technique combined with high resolution ?-ray spectrometry. The present results are compared with the available literature values as well as theoretical data calculated by the TALYS and the ALICE-IPPE computer codes. Note that production cross-sections of the 104mAg radionuclide from natPd(p,xn) processes has been measured here for the first time. Physical thick target yields for the investigated radionuclides were deduced from the respective threshold energy to 41 MeV taking into account that the total energy is absorbed in the targets. Measured data of the short-lived 103Ag radionuclide are noteworthy due to its possible applications as a precursor for the indirect production of widely used therapeutic 103Pd radionuclide via natPd(p,xn)103Ag ? 103Pd processes. On the other hand, the investigated 104Ag radionuclide finds importance due to its potential use as a diagnostic and positron emission tomography (PET) imaging analogue. Above all, measured data will enrich the literature database leading to various applications in science and technology.

Khandaker, Mayeen Uddin; Kim, Kwangsoo; Kim, Guinyun

2012-03-01

153

Actinium-225 in targeted alpha-particle therapeutic applications.  

PubMed

Alpha particle-emitting isotopes are being investigated in radioimmunotherapeutic applications because of their unparalleled cytotoxicity when targeted to cancer and their relative lack of toxicity towards untargeted normal tissue. Actinium- 225 has been developed into potent targeting drug constructs and is in clinical use against acute myelogenous leukemia. The key properties of the alpha particles generated by 225Ac are the following: i) limited range in tissue of a few cell diameters; ii) high linear energy transfer leading to dense radiation damage along each alpha track; iii) a 10 day halflife; and iv) four net alpha particles emitted per decay. Targeting 225Ac-drug constructs have potential in the treatment of cancer. PMID:22202153

Scheinberg, David A; McDevitt, Michael R

2011-10-01

154

Direct high-resolution alpha spectrometry from nuclear fuel particles in an outdoor air sample.  

PubMed

The potential use of direct high-resolution alpha spectrometry to identify the presence of transactinium elements in air samples is illustrated in the case when alpha-particle-emitting radionuclides are incorporated in nuclear fuel particles. Alpha particle energy spectra are generated through Monte Carlo simulations assuming a nuclide composition similar to RBMK (Chernobyl) nuclear fuel. The major alpha-particle-emitting radionuclides, in terms of activity, are 242Cm, 239Pu and 240Pu. The characteristics of the alpha peaks are determined by fuel particle properties as well as the type of the air filter. It is shown that direct alpha spectrometry can be readily applied to membrane filter samples containing nuclear fuel particles when rapid nuclide identification is of relevance. However, the development of a novel spectrum analysis code is a prerequisite for unfolding complex alpha spectra. PMID:17951235

Pllnen, R; Siiskonen, T

2007-10-19

155

Method for net decrease of hazardous radioactive nuclear waste materials. [Thermal neutron irradiation of long-lived radionuclides to produce stable nuclides and short-lived radionuclides  

SciTech Connect

A method of decreasing the amount of relatively long lived fission products in radioactive waste materials in excess of that due to their natural radioactive decay by producing relatively short lived radioactive nuclides and stable nuclides from the relatively long lived fission products is described comprising the steps of: (a) separating the fission products into at least (1) physically separate groups, and (2) relatively short lived fission product radioactive nuclides and stable nuclides; (b) storing the relatively short lived radioactive nuclides and stable nuclides; (c) exposing at least the groups containing Kr/sup 85/, Sr/sup 90/, Zr/sup 93/, Tc/sup 99/, Pd/sup 107/, I/sup 129/, Cs/sup 135/, Sm/sup 151/ + Eu, and actinides, to a high thermal neutron flux for separate, different predetermined periods of time selected in accordance with the long lived fission product nuclide in the corresponding group for inducing predetermined transformations of the relatively long lived fission product nuclides to produce relatively short lived radioactive nuclides and stable nuclides; (d) removing each exposed group containing the produced relatively short lived radioactive nuclides and stable nuclides from the high thermal neutron flux; (e) separating the removed group into (1) the produced short lived radioactive nuclides and stable nuclides, and (2) a plurality of further groups having long lived fission product nuclides respectively corresponding to at least some of the long lived fission product nuclides or the groups of step (a); (f) storing the produced short lived radioactive nuclides and stable nuclides; (g) joining at least one of the further groups to at least one of the groups of step (a) having a corresponding long lived fission product nuclide.

Marriott, R.; Henyey, F.S.; Hochstim, A.R.

1988-01-26

156

Cooling of short-lived, radioactive, highly charged ions with the TITAN cooler Penning trap. Status and perspectives  

NASA Astrophysics Data System (ADS)

TITAN is an on-line facility dedicated to precision experiments with short-lived radioactive isotopes, in particular mass measurements. The achievable resolution on mass measurement, which depends on the excitation time, is limited by the half life of the radioactive ion. One way to bypass this is by increasing the charge state of the ion of interest. TITAN has the unique capability of charge-breeding radioactive ions using an electron-beam ion trap (EBIT) in combination with Penning trap mass spectrometry. However, the breeding process leads to an increase in energy spread, ? E, which in turn negatively influences the mass uncertainty. We report on the development of a cooler Penning trap which aims at reducing the energy spread of the highly charged ions prior to injection into the precision mass measurement trap. Electron and proton cooling will be tested as possible routes. Mass selective cooling techniques are also envisioned.

Simon, V. V.; Delheij, P.; Dilling, J.; Ke, Z.; Shi, W.; Gwinner, G.

2011-07-01

157

Precision mass measurements of very short-lived, neutron-rich Na isotopes using a radio-frequency spectrometer  

NASA Astrophysics Data System (ADS)

Mass measurements of high precision have been performed on sodium isotopes out to 30Na using a new technique of radio-frequency excitation of ion trajectories in a homogeneous magnetic field. This method, especially suited to very short-lived nuclides, has allowed us to significantly reduce the uncertainty in mass of the most exotic Na isotopes: a relative error of 510-7 was achieved for 28Na having a half-life of only 30.5 ms and 910-7 for the weakly produced 30Na. Verifying and minimizing binding energy uncertainties in this region of the nuclear chart is important for clarification of a long-standing problem concerning the strength of the N=20 magic shell closure. These results are the fruit of the commissioning of the new experimental program MISTRAL.

Lunney, D.; Audi, G.; Doubre, H.; Henry, S.; Monsanglant, C.; de Saint Simon, M.; Thibault, C.; Toader, C.; Borcea, C.; Bollen, G.; ISOLDE Collaboration

2001-11-01

158

Prompt gamma activation analysis (PGAA) and short-lived neutron activation analysis (NAA) applied to the characterization of legacy materials  

SciTech Connect

Without quality historical records that provide the composition of legacy materials, the elemental and/or chemical characterization of such materials requires a manual analytical strategy that may expose the analyst to unknown toxicological hazards. In addition, much of the existing legacy inventory also incorporates radioactivity, and, although radiological composition may be determined by various nuclear-analytical methods, most importantly, gamma-spectroscopy, current methods of chemical characterization still require direct sample manipulation, thereby presenting special problems with broad implications for both the analyst and the environment. Alternately, prompt gamma activation analysis (PGAA) provides a'single-shot' in-situ, non-destructive method that provides a complete assay of all major entrained elemental constituents.1-3. Additionally, neutron activation analysis (NAA) using short-lived activation products complements PGAA and is especially useful when NAA activation surpasses the PGAA in elemental sensitivity.

Firestone, Richard B; English, G.A.; Firestone, R.B.; Perry, D.L.; Reijonen, J.P.; Leung, Ka-Ngo; Garabedian, G.F.; Molnar, G.L.; Revay, Zs.

2008-02-13

159

First Isochronous Time-of-Flight Mass Measurements of Short-Lived Projectile Fragments in the ESR  

SciTech Connect

A new method for precise mass measurements of short-lived hot nuclei is presented. These nuclei were produced via projectile fragmentation, separated with the FRS and injected into the storage ring ESR being operated in the isochronous mode. The revolution time of the ions is measured with a time-of-flight detector sensitive to single particles. This new method allows access to exotic nuclei with half-lives in the microsecond region. First results from this novel method obtained with measurements on neutron-deficient fragments of a chromium primary beam with half-lives down to 50 ms are reported. A precision of {delta}m/m {<=} 5 {center_dot} 10{sup -6} has been achieved.

Stadlmann, J.; Geissel, H.; Hausmann, M.; Nolden, F.; Radon, T.; Schatz, H.; Scheidenberger, C.; Attallah, F.; Beckert, K.; Bosch, F.; Falch, M.; Franczak, B.; Franzke, B.; Kerscher, Th.; Klepper, O.; Kluge, H.J.; Kozhuharov, C.; Loebner, K.E.G.; Muenzenberg, G.; Novikov, Yu.N.; Steck, M.; Sun, Z.; Suemmerer, K.; Weick, H.; Wollnik, H.

2000-12-31

160

Thyroid cancer in the Marshallese: relative risk of short-lived internal emitters and external radiation exposure  

SciTech Connect

In a study of the comparative effects of internal versus external irradiation of the thyroid in young people, we determined that the dose from internal irradiation of the thyroid with short-lived internal emitters produced several times less thyroid cancer than did the same dose of radiation given externally. We determined this finding for a group of 85 Marshall Islands children, who were less than 10 years of age at the time of exposure and who were accidentially exposed to internal and external thyroid radiation at an average level of 1400 rad. The external risk coefficient ranged between 2.5 and 4.9 cancers per million person-rad-years at risk, and thus, from our computations, the internal risk coefficient for the Marshallese children was estimated to range between 1.0 and 1.4 cancers per million person-rad-years at risk. In contrast, for individual more than 10 years of age at the time of exposure, the dose from internal irradiation of the thyroid with short-lived internal emitters produced several times more thyroid cancer than did the same dose of radiation given externally. The external risk coefficients for the older age groups were reported in the literature to be in the range of 1.0 to 3.3 cancers per million person-rad-years-at risk. We computed internal risk coefficients of 3.3 to 8.1 cancers per million person-rad-years at risk for adolescent and adult groups. This higher sensitivity to cancer induction in the exposed adolescents and adults, is different from that seen in other exposed groups. 14 refs., 8 tabs.

Lessard, E.T.; Brill, A.B.; Adams, W.H.

1985-01-01

161

Novel biogenic iodine-containing trihalomethanes and other short-lived halocarbons in the coastal East Atlantic  

NASA Astrophysics Data System (ADS)

Reactive halogen photochemistry and its impact on tropospheric oxidant levels have recently attracted intense research interest following the observation of the iodine oxide radical at midlatitudes. During September 1998, short-lived organoiodines including CH3I, C2H5I, CH2ICl, CH2IBr, CH2I2, and the hitherto undetected CHIBr2, as well as the organobromines CHBr3, CH2Br2, CHBr2Cl, CH3Br, and C2H5Br, were measured in air and seawater at and around Mace Head, on the west coast of Ireland. The release rates of organic bromines and iodines from seaweeds were determined from incubations of 10 species of brown, red, and green macroalgae collected in the intertidal or subtidal zones of the rocky shore. For all the brown algae studied, iodine was released mainly as CH2I2. However, for several seaweeds, the novel iodine-containing trihalomethanes CHIBr2 and CHI2Cl represented a significant fraction of the released organic iodine. The macroalgae incubation experiments as well as monitoring of the in situ concentrations in a rock pool indicated that natural halocarbon production by seaweeds was stimulated by incident light. The halocarbon fluxes derived from the seaweed incubations, coupled with published detailed biomass surveys, enabled coastal organohalogen seawater concentrations to be estimated. The CHBr3, CH2Br2, and CHBr2Cl concentrations calculated by this method compared well with coastal surface seawater measurements, implying that macroalgae were the major sources of the polybromomethanes. Measured CH3Br, CH3I, and CH2ICl levels were higher than calculated, which may be due to the existence of additional sources. CH3Br production by macroalgae accounted for less than 10% of measured levels in coastal waters. Short-lived iodocarbons such as CH2I2 and CHIBr2 were depleted in surface seawater compared to calculated levels, implying their photolytic loss within the upper water column.

Carpenter, L. J.; Malin, G.; Liss, P. S.; Kpper, F. C.

2000-12-01

162

Short-lived Absorptive Type III-like Microwave Bursts as a Signature of Fragmented Electron Injections  

NASA Astrophysics Data System (ADS)

In this paper, we devote ourselves to interpreting the short-lived absorptive type III-like microwave bursts in the 2006 December 13 flare event observed with high temporal and spectral resolutions (8 ms and 10 MHz) by the Chinese Solar Broadband Radio Spectrometer (SBRS/Huairou) at 2.6-3.8 GHz. In the decimeter-centimeter wavelength range, we first present the observations of short-lived bursts represented as a number of absorptive ``spikes'' superposed on the type IV continuum that can be connected by fast-drifting lines. The mean drift rate, the instantaneous bandwidth, and the absorption depth of these absorptive spikes are about -12 GHz s-1, 70 MHz, and 40%, respectively. The duration at a single frequency band can be less than the instrument resolution of 8 ms. On the basis of numerical investigations of the loss-cone instability, we suggest that fragmented electron injections with durations of as short as several milliseconds into the loss cone could be the most appropriate mechanism with which to explain the bursts. The length of an electron beam is estimated to be about 400 km, on the basis of the observational results. These injections may be related to the fragmented energy release processes during the flare. We also observe some absorptive type III-like bursts accompanying ordinary type III bursts with reverse drifts. They start at the same frequency, and the starting frequency slowly drifts to the low-frequency region. This could be a signature of propagating bidirectional electron beams originating near the reconnection region.

Chen, Bin; Yan, Yihua

2008-12-01

163

Realizing the potential of the Actinium-225 radionuclide generator in targeted alpha-particle therapy applications  

PubMed Central

Alpha particle-emitting isotopes have been proposed as novel cytotoxic agents for augmenting targeted therapy. Properties of alpha particle radiation such as their limited range in tissue of a few cell diameters and their high linear energy transfer leading to dense radiation damage along each alpha track are promising in the treatment of cancer, especially when single cells or clusters of tumor cells are targeted. Actinium-225 (225Ac) is an alpha particle-emitting radionuclide that generates 4 net alpha particle isotopes in a short decay chain to stable 209Bi, and as such can be described as an alpha particle nanogenerator. This article reviews the literature pertaining to the research, development, and utilization of targeted 225Ac to potently and specifically affect cancer.

Miederer, Matthias; Scheinberg, David A.; McDevitt, Michael R.

2013-01-01

164

Realizing the potential of the Actinium-225 radionuclide generator in targeted alpha particle therapy applications.  

PubMed

Alpha particle-emitting isotopes have been proposed as novel cytotoxic agents for augmenting targeted therapy. Properties of alpha particle radiation such as their limited range in tissue of a few cell diameters and their high linear energy transfer leading to dense radiation damage along each alpha track are promising in the treatment of cancer, especially when single cells or clusters of tumor cells are targeted. Actinium-225 (225 Ac) is an alpha particle-emitting radionuclide that generates 4 net alpha particle isotopes in a short decay chain to stable 209 Bi, and as such can be described as an alpha particle nanogenerator. This article reviews the literature pertaining to the research, development, and utilization of targeted 225 Ac to potently and specifically affect cancer. PMID:18514364

Miederer, Matthias; Scheinberg, David A; McDevitt, Michael R

2008-04-23

165

Cross Sections Needed for the Interpretation of Long-Lived and Short-Lived Cosmogenic Nuclide Production in Extraterrestrial Materials  

NASA Astrophysics Data System (ADS)

Radionuclides produced by cosmic rays in extraterrestrial materials archive information that can be used to determine cosmic-ray fluxes and to study the history of the irradiated object. Long-lived radionuclides give information about the last ~5 Myr; short-lived radionuclides give information about recent events. To calculate the solar cosmic ray (SCR) flux from measured depth profiles for cosmogenic radionuclides produced in lunar rocks, accurate and precise cross section values for the production of these radionuclides from all relevant elements are needed. About 98% of SCR and ~87% of galactic cosmic rays (GCR) falling on extraterrestrial materials are protons. Cross section measurements were made using three proton accelerators to cover the energy range ~20 - 500 MeV. Thin target techniques used in the irradiations minimized the number of protons scattered out of the stack and the neutron production within the stack. After irradiation, the short-lived radionuclides e.g. 22Na, 7Be, 24Na, 54Mn, and 56Co were determined using gamma-ray spectroscopy. 14C, 10Be, and 26Al were determined using Accelerator Mass Spectrometry. Our main objective is to measure the production cross sections of long-lived radionuclides. We have reported new cross section values for making 10Be from O and 14C from O, Mg, Al, Si, Fe, and Ni [1,2]. Using these new results, better estimates for the solar proton flux over several time periods in the past were determined [3]. However, no single value for the SCR flux could explain the measured data from different time periods. Further cross section measurements are being made to verify that the values used in these estimates were accurate. Irradiations designed to give good cross section measurements for long-lived radionuclides also give good cross section measurements for short-lived radionuclides. Results will be presented for proton production cross sections of 22Na from Mg, Al and Si, and 54Mn and 56Co from Fe and Ni; some values at low energies were reported previously [4]. These cross sections and other reported measurements [5, 6] will be used to improve the estimates of the recent SCR fluxes from the depth profiles for 22Na measured in lunar rocks [7, 8], and to better understand the SCR cosmogenic radionuclide production observed in Salem [9] and other other extraterrestrial materials. References: [1] Sisterson J. M. et al. (1992) LPS XXIII, 1305. [2] Sisterson J. M. et al. (1995) LPS XXVI, 1309. [3] Rao M. N. et al. (1994) GCA, 58, 4231. [4] Beverding A. M. et al. (1994) USGS Circular 1107, 29. [5] Michel R. and Stueck R. (1984) Proc. LPSC 14th, in JGR, 89, B673. [6] Bodemann R. et al. (1993) Nucl. Instr. Meth. Phys. Res., B82, 9. [7] Reedy R. C. (1977) Proc. LSC 8th, 825. [8] Fruchter J. S. et al. (1982) LPS XIII, 243. [9] Evans J. C. et al. (1987) LPS XVIII, 271.

Sisterson, J. M.; Beverding, A.; Kim, K. J.; Englert, P. A. J.; Jull, A. J. T.; Donahue, D. J.; Cloudt, S.; Castaneda, C.; Vincent, J.; Caffee, M. W.; Osazuwa, C. O.; Reedy, R. C.

1995-09-01

166

Li and B isotopic variations in an Allende CAI: Evidence for the in situ decay of short-lived 10Be and for the possible presence of the short-lived nuclide 7Be in the early solar system  

NASA Astrophysics Data System (ADS)

The concentrations and isotopic compositions of lithium, beryllium, and boron, analyzed in situ by ion microprobe in 66 spots of a type B1 Ca-Al-rich inclusion (CAI 3529-41) from the Allende meteorite, are reported. Large variations are observed for both the Li and the B isotopic ratios with 7Li/ 6Li ranging from 9.2 0.22 to 12.22 0.43 (a ?250 range in ?7Li values) and 10B/ 11B ranging from 0.2468 0.0057 to 0.4189 0.0493 (a 410 range in ?11B values). The very low Li concentrations (<1 ppb) observed in several anorthite and fassaite grains require that a correction for the contribution of spallogenic Li produced during irradiation of the Allende meteoroid by galactic cosmic rays (GCR) be made (after this correction 7Li/ 6Li ranges from 9.2 0.22 to 13.44 0.56, i.e., a ?350 range in ?7Li values). In 3529-41, the 10B/ 11B ratios are positively correlated with 9Be/ 11B in a manner indicating the in situ decay of short-lived 10Be (half-life = 1.5 Ma) with a 10Be/ 9Be ratio at the time of formation of the CAI of 8.8 0.6 10 -4, which is in agreement with previous findings [McKeegan, K.D., Chaussidon, M., Robert, F., 2000. Incorporation of short-lived 10Be in a calcium-aluminum-rich inclusion from the Allende meteorite. Science289, 1334-1337]. The present detailed investigation demonstrates that only minor perturbations of the 10Be- 10B system are present in 3529-41, contrary to the 26Al/ 26Mg system for which numerous examples of isotopic redistribution following crystallization were observed [Podosek, F.A., Zinner, E.K., MacPherson, G.J., Lundberg, L.L., Brannon, J.C., Fahey, A.J., 1991. Correlated study of initial 87Sr/ 86Sr and Al-Mg systematics and petrologic properties in a suite of refractory inclusions from the Allende meteorite. Geochim. Cosmochim. Acta55, 1083-1110]. Petrographically based criteria were developed to identify within the 66 analyzed spots in 3529-41, those where post-magmatic perturbation of the Li and Be distributions occurred. Li and Be concentrations measured in different analytical spots are compared with those predicted by using experimentally determined partition coefficients according to a model of closed-system crystallization of the CAI melt. These criteria show that 56% of the spots in melilite, 38% in anorthite, and 8% in fassaite suffered post-crystallization perturbations of Li and/or Be distributions. In the remaining spots, which do not show obvious indication of redistribution of Li or Be, the 7Li/ 6Li isotopic variations (corrected for GCR exposure) are positively correlated with 9Be/ 6Li suggesting the in situ decay of now-extinct 7Be. The derived isochron implies that at the time of its formation, the CAI melt had a 7Be/ 9Be ratio of 0.0061 0.0013 and a 7Li/ 6Li ratio of 11.49 0.13. In contrast, all the spots in 3529-41, which do show evidence for post-magmatic redistribution of Li and Be, have relatively constant 7Li/ 6Li, averaging 11.72 0.56, which is consistent with mass balance calculations for Li isotopic homogenization in the CAI after the decay of 7Be. The incorporation of live 7Be in 3529-41 requires, because of the very short half-life of this nuclide (53 days), that it be produced essentially contemporaneously with the formation of the CAI. Therefore, the irradiation processes responsible for production of 7Be must have occurred within the solar accretion disk. Calculations developed in the framework of the x-wind model [Gounelle, M., Shu, F.H., Shang, H., Glassgold, A.E., Rehm, E.K., Lee, T., 2004. The origin of short-lived radionuclides and early Solar System irradiation (abstract). Lunar Planet. Sci.35, 1829] reproduce the 7Be and 10Be abundances observed in 3529-41. The correlated presence of 7Be and 10Be in 3529-41 is thus a strong argument that 10Be, which is observed rather ubiquitously in CAIs, is also a product of irradiation in the early solar system, as might be a significant fraction of other short-lived radionuclides observed in early solar system materials.

Chaussidon, Marc; Robert, Franois; McKeegan, Kevin D.

2006-01-01

167

NOVEL METHOD FOR BEAM DYNAMICS STUDY USING AN ALPHA PARTICLE SOURCE  

Microsoft Academic Search

A new method for beam dynamic study has been devel- oped by using alpha particles emitted from a commercially available radioactive source. The precision of the method is estimated in consideration of an event rate in a reason- able measuring time and statistical accuracy. The method could be applied not only for a circular accelerator but also for a unit

A. Sato; M. Aoki; Y. Arimoto; T. Itahashi; Y. Kuno; T. Oki; M. Yoshida

168

Petrological and geochemical records of short-lived, high temperature metamorphism during exhumation of the Sulu UHP metamorphic terrane  

NASA Astrophysics Data System (ADS)

The Dabie-Sulu terrane of east-central China is the largest and most well known ultrahigh-pressure (UHP) metamorphic terrane in the world, which has become one of the most important places to study continental subduction-related UHP metamorphism. In the past two decades, numerous petrological, geochemical, petrophysical and tectonophysical studies were carried out in the Dabie-Sulu UHP metamorphic terrane. However, almost all of these studies have focused on UHP metamorphic processes, while only a few studies have focused on the thermal evolution. Here we present a detailed petrological and geochemical study on the southern Sulu UHP eclogites in order to constrain the hot exhumation of the Sulu UHP metamorphic terrane. Eclogite-hosted garnet-spinel-corundum-quartz-bearing titanohematite veins near the main hole of the Chinese Continental Scientific Drilling Project (CCSD-MH) are described for the first time in the Sulu UHP metamorphic terrane. A vein composed of titanohematite + ilmenite + hematite + spinel + garnet + corundum + quartz + K-feldspar + albite was studied in detail. The unusual mineral assemblage of garnet + spinel + corundum + quartz implies that this vein could have experienced high temperatures (>900 oC). Although within garnets showed well-defined Mg and Mn diffusion zoning in the rim as a result of the high temperature event, slight Mg and Mn growth zoning was preserved in the core. Thus, we suggest that the Sulu UHP terrane could have experienced a short-lived, high-temperature stage during exhumation. This is consistent with trace element zoning recorded by garnet, omphacite and apatite and much higher temperatures recorded by rutiles and zircons with ages of ~200 Ma in the CCSD-MH eclogites. We speculate that slab breakoff may have caused asthenospheric upwelling, which could have provided a heat pulse for the short-lived, high-temperature metamorphism in the Sulu UHP terrane. Such high temperature stage could have contributed to the overprinting of granulite-facies metamorphism on eclogites and widespread partial melting in the Sulu UHP terrane.

Zong, K.; Liu, Y.; Zhang, X.; Ye, Y.; Gao, C.

2010-12-01

169

Fecal cortisol levels predict breeding but not survival of females in the short-lived rodent, Octodon degus.  

PubMed

The cort-adaptation hypothesis indicates that an association between glucocorticoid (cort) levels and fitness may vary with the extent to which reproduction or breeding effort is a major determinant of cort levels. Support for a context dependent association between cort and fitness comes mostly from relatively long-lived, bird species. We tested the hypothesis that there are gender and context (life-history) specific cort-fitness relationships in degus, a short-lived and generally semelparous social rodent. In particular, we used demographical records on a natural population to estimate adult survival through seasons and years and linked that to records of baseline cort (based on fecal cortisol metabolites). We found no evidence for a direct relationship between baseline cort and adult survival across seasons, and this lack of association was recorded irrespective of sex and life history stage. Yet, cort levels during early lactation predicted the probability that females produce a second litter during the same breeding season, supporting a connection between baseline cort levels and breeding effort. Overall, the differential effects of cort on survival and breeding supported that the extent of cort-fitness relationships depends on the fitness component examined. PMID:23524002

Ebensperger, Luis A; Tapia, Diego; Ramrez-Estrada, Juan; Len, Cecilia; Soto-Gamboa, Mauricio; Hayes, Loren D

2013-03-21

170

Mood regulation in youth: research findings and clinical approaches to irritability and short-lived episodes of mania like symptoms  

PubMed Central

Purpose of review Mood regulation problems, such as severe chronic irritability or short episodes of mania like symptoms are common, impairing and a topic of intense recent interest to clinicians, researchers and the DSM-5 process. Here we review the most recent findings about these two presentations and discuss approaches to their treatment. Recent findings Longitudinal and genetic findings suggest that chronic irritability should be regarded as a mood problem that is distinct from bipolar disorder. A proportion of children with short (less than 4 days) episodes of mania like symptoms seem to progress to classical (Type I or II) bipolar disorder over time in US clinic samples. In a UK sample, such episodes were independently associated with psychosocial impairment. The evidence base for the treatment of either irritability or short-lived episodes to mania-like symptoms is still small. Clinicians should be cautious with extrapolating treatments from classical bipolar disorder to these mood regulation problems. CBT-based approaches targeting general mood regulation processes may be effective for cases with severe irritability or short episodes of mania like symptoms. Summary There is increasing research evidence for the importance of mood regulation problems in the form of either irritability or short episodes of mania like symptoms in youth. The evidence base for their drug treatment has yet to be developed. CBT-based interventions to modify processes of mood regulation may be a useful and safe intervention for patients with these presentations.

Leigh, Eleanor; Smith, Patrick; Milavic, Gordana; Stringaris, Argyris

2013-01-01

171

Constraints on the Origin of Chondrules and CAIs from Short-Lived and Long-Lived Radionuclides  

SciTech Connect

The high time resolution Pb-Pb ages and short-lived nuclide based relative ages for CAIs and chondrules are reviewed. The solar system started at 4567.2 {+-} 0.6Ma inferred from the high precision Pb-Pb ages of CAIs. Time scales of CAIs ({le}0.1Myr), chondrules (1-3Myr), and early asteroidal differentiation ({ge}3Myr) inferred from {sup 26}Al relative ages are comparable to the time scale estimated from astronomical observations of young star; proto star, classical T Tauri star and week-lined T Tauri star, respectively. Pb-Pb ages of chondrules also indicate chondrule formation occur within 1-3 Myr after CAIs. Mn-Cr isochron ages of chondrules are similar to or within 2 Myr after CAI formation. Chondrules from different classes of chondrites show the same range of {sup 26}Al ages in spite of their different oxygen isotopes, indicating that chondrule formed in the localized environment. The {sup 26}Al ages of chondrules in each chondrite class show a hint of correlation with their chemical compositions, which implies the process of elemental fractionation during chondrule formation events.

Kita, N T; Huss, G R; Tachibana, S; Amelin, Y; Nyquist, L E; Hutcheon, I D

2005-10-24

172

Impact of very short-lived halogens on stratospheric ozone abundance and UV radiation in a geo-engineered atmosphere  

NASA Astrophysics Data System (ADS)

The impact of very short-lived (VSL) halogenated source species on the ozone layer and surface erythemal ultraviolet radiation (UVERY) is investigated in the context of geo-engineering of climate by stratospheric sulfur injection. For a projected 2040 model atmosphere, consideration of VSL halogens at their upper limit results in lower ozone columns and higher UVERY due to geo-engineering for nearly all seasons and latitudes, with UVERY rising by 12% and 6% in southern and northern high latitudes, respectively. When VSL halogen sources are neglected, future UVERY increases due to declines in ozone column are nearly balanced by reductions of UVERY due to scattering by the higher stratospheric aerosol burden in mid-latitudes. Consideration of VSL sources at their upper limit tips the balance, resulting in annual average increases in UVERY of up to 5% in mid and high latitudes. Therefore, VSL halogens should be considered in models that assess the impact of stratospheric sulfur injections on the ozone layer.

Tilmes, S.; Kinnison, D. E.; Garcia, R. R.; Salawitch, R.; Canty, T.; Lee-Taylor, J.; Madronich, S.; Chance, K.

2012-11-01

173

Impact of very short-lived halogens on stratospheric ozone abundance and UV radiation in a geo-engineered atmosphere  

NASA Astrophysics Data System (ADS)

The impact of very short-lived (VSL) halogenated source species on the ozone layer and surface erythemal ultraviolet radiation (UVERY) is investigated in the context of geo-engineering of climate by stratospheric sulfur injection. For a projected 2040 model atmosphere, consideration of VSL halogens at their upper limit results in lower ozone columns and higher UVERY due to geo-engineering for nearly all seasons and latitudes, with UVERY rising by 12% and 6% in southern and northern high latitudes, respectively. When VSL halogen sources are neglected, future UVERY increases due to declines in ozone column are nearly balanced by reductions of UVERY due to scattering by the higher stratospheric aerosol burden in mid-latitudes. Consideration of VSL sources at their upper limit tips the balance, resulting in annual average increases in UVERY of up to 5% in mid and high latitudes. Therefore, VSL halogens should be considered in models that assess the impact of stratospheric sulfur injections on the ozone layer.

Tilmes, S.; Kinnison, D. E.; Garcia, R. R.; Salawitch, R.; Canty, T.; Lee-Taylor, J.; Madronich, S.; Chance, K.

2012-08-01

174

Role of Sec61p in the ER-associated degradation of short-lived transmembrane proteins.  

PubMed

Misfolded proteins in the endoplasmic reticulum (ER) are identified and degraded by the ER-associated degradation pathway (ERAD), a component of ER quality control. In ERAD, misfolded proteins are removed from the ER by retrotranslocation into the cytosol where they are degraded by the ubiquitin-proteasome system. The identity of the specific protein components responsible for retrotranslocation remains controversial, with the potential candidates being Sec61p, Der1p, and Doa10. We show that the cytoplasmic N-terminal domain of a short-lived transmembrane ERAD substrate is exposed to the lumen of the ER during the degradation process. The addition of N-linked glycan to the N terminus of the substrate is prevented by mutation of a specific cysteine residue of Sec61p, as well as a specific cysteine residue of the substrate protein. We show that the substrate protein forms a disulfide-linked complex to Sec61p, suggesting that at least part of the retrotranslocation process involves Sec61p. PMID:18573918

Scott, Daniel C; Schekman, Randy

2008-06-23

175

Transposon-Mediated Transgenesis in the Short-Lived African Killifish Nothobranchius furzeri, a Vertebrate Model for Aging  

PubMed Central

The African killifish Nothobranchius furzeri is the shortest-lived vertebrate that can be bred in captivity. N. furzeri comprises several wild-derived strains with striking differences in longevity ranging from 3 to 9 months, which makes it a powerful vertebrate model for aging research. The short life cycle of N. furzeri should also facilitate studies on adult traits that are specific to vertebrates. Although progress has been made to generate a genetic linkage map and to start sequencing the genome of N. furzeri, tools to genetically manipulate this species of fish have not yet been developed. Here, we report the first establishment of transgenesis in N. furzeri. We use the Tol2 transposase system to generate transgenic N. furzeri that express green fluorescent protein driven by the Xenopus cytoskeletal actin promoter or the zebrafish heat-shock protein 70 promoter. We successfully generate stable transgenic lines of N. furzeri with germline transmission of integrated transgene. The development of transgenesis in N. furzeri provides a powerful tool to investigate the mechanisms underlying aging and longevity in a short-lived vertebrate model. Transgenesis in this fish will also facilitate the study of other phenotypes, including adult tissue regeneration and cognitive behavior.

Valenzano, Dario Riccardo; Sharp, Sabrina; Brunet, Anne

2011-01-01

176

Occurrence of adventitious sprouting in short-lived monocarpic herbs: a field study of 22 weedy species  

PubMed Central

Background and Aims Adventitious sprouting from the hypocotyle and roots in monocarpic herbs has been confirmed in previous experimental studies as a means to avoid bud limitation after severe injury in annual and biennial plants. Data regarding the role of adventitious sprouting in natural populations, however, were lacking. The aim of the present study was to assess whether adventitious sprouting occurs in natural populations and how it is affected by plant size, plant injury, plant cover and environmental characteristics. Methods Data were sampled from 14 037 individual plants from 389 populations belonging to 22 annual and biennial species. Growth parameters were measured in individual plants, species composition and plant cover in communities were evaluated, and environmental characteristics were estimated using Ellenberg indicator values. Key Results It was confirmed that adventitious sprouting occurs in natural populations of all but five species examined. Adventitious sprouting was positively affected by plant size and plant injury. Environmental factors including availability of soil nitrogen were not shown to affect adventitious sprouting. Annual and biennial plants did not differ in sprouting, but upright annuals had a lower number of and longer adventitious shoots than prostrate annuals. Conclusions Adventitious bud formation is used to overcome meristem limitation when stem parts are lost due to injury, and thus resprouting in short-lived monocarps should not be overlooked.

Malikova, Lenka; Smilauer, Petr; Klimesova, Jitka

2010-01-01

177

Technical Note: Ensuring consistent, global measurements of short-lived halocarbon gases in the ocean and atmosphere  

NASA Astrophysics Data System (ADS)

Short-lived halocarbons are significant sources of reactive halogen in the troposphere and likely the lower stratosphere. Quantifying ambient concentrations in the surface ocean and atmosphere is essential for understanding the impact of fluxes of these gases on marine boundary layer oxidation and lower stratospheric ozone-depletion processes. Despite the body of literature increasing substantially over recent years, calibration issues complicate comparison of results and limit the utility of building larger-scale databases that would enable further development of the science (e.g. sea-air flux quantification, model validation, etc.). With this in mind, thirty-two scientists representing eight nations and from both atmospheric and oceanic halocarbon communities gathered in London in February 2008 to discuss the scientific issues and plan an international effort toward a common calibration scale. Here, we discuss the outputs from this meeting, suggest the compounds that should be targeted initially, identify opportunities for beginning calibration and comparison efforts, and make recommendations for ways to improve the comparability of previous and future measurements.

Butler, J. H.; Bell, T. G.; Hall, B. D.; Quack, B.; Carpenter, L. J.; Williams, J.

2009-05-01

178

Technical Note: Ensuring consistent, global measurements of very short-lived halocarbon gases in the ocean and atmosphere  

NASA Astrophysics Data System (ADS)

Very short-lived halocarbons are significant sources of reactive halogen in the marine boundary layer, and likely in the upper troposphere and lower stratosphere. Quantifying ambient concentrations in the surface ocean and atmosphere is essential for understanding the atmospheric impact of these trace gas fluxes. Despite the body of literature increasing substantially over recent years, calibration issues complicate the comparison of results and limit the utility of building larger-scale databases that would enable further development of the science (e.g. sea-air flux quantification, model validation, etc.). With this in mind, thirty-one scientists from both atmospheric and oceanic halocarbon communities in eight nations gathered in London in February 2008 to discuss the scientific issues and plan an international effort toward developing common calibration scales (http://tinyurl.com/c9cg58). Here, we discuss the outputs from this meeting, suggest the compounds that should be targeted initially, identify opportunities for beginning calibration and comparison efforts, and make recommendations for ways to improve the comparability of previous and future measurements.

Butler, J. H.; Bell, T. G.; Hall, B. D.; Quack, B.; Carpenter, L. J.; Williams, J.

2010-01-01

179

Excited states of tryptophan in cod parvalbumin. Identification of a short-lived emitting triplet state at room temperature.  

PubMed Central

The fluorescence and phosphorescence spectra of model indole compounds and of cod parvalbumin III, a protein containing a single tryptophan and no tyrosine, were examined in the time scale ranging from subnanoseconds to milliseconds at 25 degrees C in aqueous buffer. For both Ca- bound and Ca-free parvalbumin and for model indole compounds that contained a proton donor, a phosphorescent species emitting at 450 nm with a lifetime of approximately 20-40 ns could be identified. A longer-lived phosphorescence is also apparent; it has approximately the same absorption and emission spectrum as the short-lived triplet molecule. For Ca parvalbumin, the decay of the long-lived triplet tryptophan is roughly exponential with a lifetime of 4.7 ms at 25 degrees C whereas for N-acetyltryptophanamide in aqueous buffer the decay lifetime was 30 microseconds. In contrast, the lifetime of the long-lived tryptophan species is much shorter in the Ca-free protein compared with Ca parvalbumin, and the decay shows complex nonexponential kinetics over the entire time range from 100 ns to 1 ms. It is concluded that the photochemistry of tryptophan must take into account the existence of two excited triplet species and that there are quenching moieties within the protein matrix that decrease the phosphorescence yield in a dynamic manner for the Ca-depleted parvalbumin. In contrast, for Ca parvalbumin, the tryptophan site is rigid on the time scale of milliseconds.

Sudhakar, K; Phillips, C M; Williams, S A; Vanderkooi, J M

1993-01-01

180

Identification of the short-lived Au(N3)42- dianion from its Coulomb explosion products  

NASA Astrophysics Data System (ADS)

In high-energy collisions between Au(N3)4- anions and sodium vapor, electron transfer occurred to produce Au(N3)42- dianions. These were short-lived (sub microsecond) and Coulomb exploded into Au(N3)3- and N3- with a kinetic energy release of 2.6 +/- 0.5 eV. In the product ion spectra, peaks correspond to fragment ions formed from collisionally activated Au(N3)4- parent anions. Loss of one or more N3 or N2 produced AuNn- complexes (n = 1-4, 6, 9-10) whereas complexes with n = 5, 7, and 8 were not detected. These ions can be assigned to gold-nitride-azide complexes Au(N)x(N3)y- (x = 0-2 and y = 0-4). Cationic complexes were measured for n = 1-4 and 6. Sodium vapor collision experiments were also performed for Au(N3)2-, which is generated in situ by the spontaneous reduction of Au(N3)42- and concurrent azide dissociation. In this case there was no clear signature indicative of the formation of a dianion. The formation of dianions cannot be excluded, however, since such ions may decay by electron emission instead of dissociation into two singly charged fragment ions.

Drenck, Kasper; Hvelplund, Preben; McKenzie, Christine J.; Nielsen, Steen Brndsted

2005-07-01

181

Quantification of radiation dose from short-lived positron emitters formed in human tissue under proton therapy conditions  

NASA Astrophysics Data System (ADS)

The dose distribution in proton therapy is mainly due to primary particles and secondary electrons. The contribution of short-lived ?+ emitters formed in the interactions of protons with the light mass elements C, N and O has hitherto not been considered. We estimated the formation of 11C, 13N and 15O in irradiation of tissue with 200 MeV protons. The integral yields at 150 MeV were compared with a literature phantom measurement. The results for 11C and 15O agreed very well; for 13N, however, appreciable deviation was observed. The activities were also calculated in the region around the Bragg peak as well as over the path length after entrance of the beam. Dose calculations were then done using the medical internal radiation dose (MIRD) formalism. Furthermore, a dose calculation was simulated for a 150 MeV proton beam (2 nA, 2 min) in a brain tumour. The dose deposited by the positron emitters in the Bragg peak region was found to be about 1.5 mGy, i.e. less than 1% of the dose estimated from the electronic interactions of protons. The absorbed dose in the whole brain amounted to 5.5 mGy.

Kettern, K.; Coenen, H. H.; Qaim, S. M.

2009-06-01

182

Garnet-spinel-corundum-quartz-bearing titanohematite veins in eclogite from the Sulu ultrahigh-pressure terrane: Imprint of a short-lived, high-temperature metamorphic stage  

NASA Astrophysics Data System (ADS)

Mineral assemblage of spinel + corundum + quartz was reported in the Sulu UHP belt. Unusual spinel + corundum + quartz assemblage implies a high-T condition (>900 C). Growth zoning preserved in the garnet implies that high-T stage is short-lived. High-T could have induced granulite-facies metamorphism and partial melting.

Zong, Keqing; Liu, Yongsheng; Gao, Changgui; Hu, Zhaochu; Gao, Shan

2011-09-01

183

A novel approach based on nanotechnology for investigating the chronic actions of short-lived peptides in specific sites of the brain  

Microsoft Academic Search

This review presents a novel experimental approach for investigating the chronic actions of short-lived peptides in specific sites of the brain. This method combines the advantages of three different techniques: liposome encapsulation, site-specific microinjection and telemetry. First, liposomes can be designed to remain located at the injection site for a long period of time, where they protect encapsulated peptide from

Frdric Frzard; Neila M. Silva-Barcellos; Robson A. S. dos Santos

2007-01-01

184

Newly designed modifier prolongs the action of short-lived peptides and proteins by allowing their binding to serum albumin.  

PubMed

We found that human serum albumin (HSA) contains a single binding domain for derivatives of long-chain fatty acid (LCFA)-like molecules in which the carboxylate is replaced by sulfonate. Accordingly, we have synthesized 16-sulfo-hexadecanoic acid-N-hydroxysuccinimide ester [HO(3)S-(CH(2))(15)-CONHS], an agent that reacts selectively with the amino side chains of peptides and proteins. A macromolecule containing a single 16-sulfohexadecanoate moiety associating with albumin with a K(a) value of 0.83 0.08 10(6) M(-1), a sufficient affinity to extend the actions in vivo of such short-lived peptides and proteins. Subcutaneous administration of insulin-NHCO-(CH(2))(15)-SO(3)(-) into mice facilitated a glucose-lowering effect 4.3 times in duration and 6.6 times in area under the curve (AUC) as compared to an in vitro equipotent amount of Zn(2+)-free insulin. Similarly, subcutaneous and intravenous administration of exendin-4-NHCO-(CH(2))(15)-SO(3)(-) to mice yielded prolonged and stable reduction in glucose level, 5-9-fold longer than that of exendin-4. Also, a single subcutaneous administration of human interferon-?2-[NH-CO-(CH(2))(15)-SO(3)(-)](3) to mice yielded circulating antiviral activity over a period of 40 h. In conclusion, a simple, hydrophilic reagent has been engineered, synthesized, and studied. Its linkage to peptides and proteins in a monomodified fashion yielded hydrophilic, prolonged acting derivatives, due to their acquired ability to associate with serum albumin after administration. PMID:22759320

Shechter, Yoram; Sasson, Keren; Lev-Goldman, Vered; Rubinraut, Sara; Rubinstein, Menachem; Fridkin, Mati

2012-07-17

185

Coastal measurements of short-lived reactive iodocarbons and bromocarbons at Roscoff, Brittany during the RHaMBLe campaign  

NASA Astrophysics Data System (ADS)

Atmospheric concentrations of the volatile reactive iodocarbons C2H5I, 1-C3H7I, 2-C3H7I, CH2ICl, CH2IBr, CH2I2 and bromocarbons CH2Br2 and CHBr3 were determined by GC/MS analysis of marine boundary layer air at Roscoff, Brittany on the northwest coast of France during September 2006. Comparison with other coastal studies suggests that emissions of these trace gases are strongly influenced by site topography, seaweed populations and distribution, as well as tide height. Concentrations of the very short-lived dihalomethanes CH2IBr and CH2I2 in particular showed evidence of tidal dependence, with higher concentrations observed at low tide during maximum exposure of seaweed beds. We also present a limited number of halocarbon concentrations in surface seawater and estimate sea-air fluxes based on simultaneous water and air measurements of these gases. CH2Br2 and CHBr3 were strongly correlated both in air and in seawater, with CH2Br2/CHBr3 ratios of 0.19 in air and 0.06 in water. The combined midday I atom flux from the photolabile diahlomethanes CH2I2, CH2IBr and CH2ICl of ~5103 molecules cm-3 s-1 is several orders of magnitude lower than the estimated I atom flux from I2 based on coinciding measurements at the same site, which indicates that at Roscoff the major I atom precursor was I2 rather than reactive iodocarbons.

Jones, C. E.; Hornsby, K. E.; Dunk, R. M.; Leigh, R. J.; Carpenter, L. J.

2009-08-01

186

Coastal measurements of short-lived reactive iodocarbons and bromocarbons at Roscoff, Brittany during the RHaMBLe campaign  

NASA Astrophysics Data System (ADS)

Atmospheric concentrations of the volatile reactive iodocarbons C2H5I, 1-C3H7I, 2-C3H7I, CH2ICl, CH2IBr, CH2I2 and bromocarbons CH2Br2 and CHBr3 were determined by GC/MS analysis of marine boundary layer air at Roscoff, Brittany on the northwest coast of France during September 2006. Comparison with other coastal studies suggests that emissions of these trace gases are strongly influenced by site topography, seaweed populations and distribution, as well as wind speed and direction and tide height. Concentrations of the very short-lived dihalomethanes CH2IBr and CH2I2 in particular showed evidence of tidal dependence, with higher concentrations observed at low tide during maximum exposure of seaweed beds. We also present a limited number of halocarbon measurements in surface seawater and estimate sea-air fluxes based on these and simultaneous air measurements. CH2Br2 and CHBr3 were strongly correlated both in air and in seawater, with CH2Br2/CHBr3 ratios of 0.19 in air and 0.06 in water. The combined midday I atom flux from the photolabile diahlomethanes CH2I2, CH2IBr and CH2ICl of ~5103 molecules cm-3 s-1 is several orders of magnitude lower than the estimated I atom flux from I2 based on coinciding measurements at the same site, which indicates that at Roscoff the major I atom precursor was I2 rather than reactive iodocarbons.

Jones, C. E.; Hornsby, K. E.; Dunk, R. M.; Leigh, R. J.; Carpenter, L. J.

2009-11-01

187

Using daily satellite observations to estimate emissions of short-lived air pollutants on a mesoscopic scale  

NASA Astrophysics Data System (ADS)

Emission inventories of air pollutants are crucial information for policy makers and form important input data for air quality models. Using satellite observations for emission estimates has important advantages over bottom-up emission inventories: they are spatially consistent, have high temporal resolution, and enable updates shortly after the satellite data become available. We present a new algorithm specifically designed to use daily satellite observations of column concentrations for fast updates of emission estimates of short-lived atmospheric constituents on a mesoscopic scale (25 25 km2). The algorithm needs only one forward model run from a chemical transport model to calculate the sensitivity of concentration to emission, using trajectory analysis to account for transport away from the source. By using a Kalman filter in the inverse step, optimal use of the a priori knowledge and the newly observed data is made. We apply the algorithm for NOx emission estimates of East China, using the CHIMERE model on a 0.25 degree resolution together with tropospheric NO2column retrievals of the OMI and GOME-2 satellite instruments. Closed loop tests show that the algorithm is capable of reproducing new emission scenarios. Applied with real satellite data, the algorithm is able to detect emerging sources (e.g., new power plants), and improves emission information for areas where proxy data are not or badly known (e.g., shipping emissions). Chemical transport model runs with the daily updated emission estimates provide better spatial and temporal agreement between observed and simulated concentrations, facilitating improved air quality forecasts.

Mijling, B.; van der A, R. J.

2012-09-01

188

ICV-Transplanted Human Glial Precursor Cells Are Short-Lived Yet Exert Immunomodulatory Effects in Mice with EAE  

PubMed Central

Human glial precursor cells (hGPs) have potential for remyelinating lesions and are an attractive cell source for cell therapy of multiple sclerosis (MS). To investigate whether transplanted hGPs can affect the pathogenesis of experimental autoimmune encephalomyelitis (EAE), an animal model of MS, we evaluated the therapeutic effects of transplanted hGPs together with the in vivo fate of these cells using magnetic resonance imaging (MRI) and bioluminescence imaging (BLI). At 14 days post-EAE induction, mice (n = 19) were intracerebroventricularly (ICV) injected with 5 105 hGPs that were magnetically labeled with superparamagnetic iron oxide (SPIO) particles as MR contrast agent and transduced with firefly luciferase for BLI of cell survival. Control mice (n = 18) received phosphate buffered saline (PBS) vehicle only. The severity of EAE clinical disability in the hGP-transplanted group was significantly suppressed (P < 0.05) with concomitant inhibition of ConA and MOG-specific T cell proliferation in the spleen. Astrogliosis was reduced and a lower activity of macrophages and/or microglia was observed in the spinal cord (P < 0.05). On MRI, SPIO signal was detected within the lateral ventricle from 1 day post-transplantation and remained there for up to 34 days. BLI indicated that most cells did not survive beyond 510 days, consistent with the lack of detectable migration into the brain parenchyma and the histological presence of an abundance of apoptotic cells. Transplanted hGPs could not be detected in the spleen. We conclude that ICV transplantation of short-lived hGPs can have a remote therapeutic effect through immunomodulation from within the ventricle, without cells directly participating in remyelination.

KIM, HEECHUL; WALCZAK, PIOTR; MUJA, NASER; CAMPANELLI, JAMES T.; BULTE, JEFF W. M.

2013-01-01

189

SHORT-LIVED STAR-FORMING GIANT CLUMPS IN COSMOLOGICAL SIMULATIONS OF z Almost-Equal-To 2 DISKS  

SciTech Connect

Many observed massive star-forming z Almost-Equal-To 2 galaxies are large disks that exhibit irregular morphologies, with Almost-Equal-To 1 kpc, Almost-Equal-To 10{sup 8}-10{sup 10}M{sub o-dot} clumps. We present the largest sample to date of high-resolution cosmological smoothed particle hydrodynamics simulations that zoom-in on the formation of individual M{sub *} Almost-Equal-To 10{sup 10.5}M{sub o-dot} galaxies in Almost-Equal-To 10{sup 12}M{sub o-dot} halos at z Almost-Equal-To 2. Our code includes strong stellar feedback parameterized as momentum-driven galactic winds. This model reproduces many characteristic features of this observed class of galaxies, such as their clumpy morphologies, smooth and monotonic velocity gradients, high gas fractions (f{sub g} Almost-Equal-To 50%), and high specific star formation rates ({approx}>1 Gyr{sup -1}). In accord with recent models, giant clumps (M{sub clump} Almost-Equal-To (5 Multiplication-Sign 10{sup 8}-10{sup 9})M{sub o-dot}) form in situ via gravitational instabilities. However, the galactic winds are critical for their subsequent evolution. The giant clumps we obtain are short-lived and are disrupted by wind-driven mass loss. They do not virialize or migrate to the galaxy centers as suggested in recent work neglecting strong winds. By phenomenologically implementing the winds that are observed from high-redshift galaxies and in particular from individual clumps, our simulations reproduce well new observational constraints on clump kinematics and clump ages. In particular, the observation that older clumps appear closer to their galaxy centers is reproduced in our simulations, as a result of inside-out formation of the disks rather than inward clump migration.

Genel, Shy; Genzel, Reinhard; Foerster Schreiber, Natascha M. [Max Planck Institut fuer extraterrestrische Physik, Giessenbachstrasse, 85748 Garching (Germany); Naab, Thorsten; Oser, Ludwig [Max Planck Institut fuer Astrophysik, Karl-Schwarzschild-Str. 1, 85741 Garching (Germany); Sternberg, Amiel [Sackler School of Physics and Astronomy, Tel Aviv University, Tel Aviv 69978 (Israel); Johansson, Peter H. [Department of Physics, University of Helsinki, Gustaf Haellstroemin katu 2a, FI-00014 Helsinki (Finland); Dave, Romeel [Astronomy Department, University of Arizona, Tucson, AZ 85721 (United States); Oppenheimer, Benjamin D. [Leiden Observatory, Leiden University, P.O. Box 9513, 2300 RA Leiden (Netherlands); Burkert, Andreas, E-mail: shy@mpe.mpg.de, E-mail: genzel@mpe.mpg.de, E-mail: forster@mpe.mpg.de, E-mail: amiel@wise.tau.ac.il, E-mail: naab@mpa-garching.mpg.de, E-mail: oser@usm.lmu.de, E-mail: burkert@usm.lmu.de, E-mail: phjohans@astro.helsinki.fi, E-mail: rad@as.arizona.edu, E-mail: oppenheimer@strw.leidenuniv.nl [Universitaets-Sternwarte Muenchen, Scheinerstr. 1, D-81679 Muenchen (Germany)

2012-01-20

190

Application of mass spectrometric techniques for the trace analysis of short-lived iodine-containing volatiles emitted by seaweed.  

PubMed

Knowledge of the composition and emission rates of iodine-containing volatiles from major widespread seaweed species is important for modeling the impact of halogens on gas-phase atmospheric chemistry, new particle formation, and climate. In this work, we present the application of mass spectrometric techniques for the quantification of short-lived iodine-containing volatiles emitted by eight different seaweeds from the intertidal zone of Helgoland, Germany. A previously developed online time-of-flight aerosol mass spectrometric method was used to determine I(2) emission rates and investigate temporally resolved emission profiles. Simultaneously, iodocarbons were preconcentrated on solid adsorbent tubes and quantified offline using thermodesorption-gas chromatography-mass spectrometry. The total iodine content of the seaweeds was determined using microwave-assisted tetramethylammonium hydroxide extraction followed by inductively coupled-plasma mass spectrometry analysis. The highest total iodine content was found in the Laminariales, followed by the brown algae Ascophyllum nodosum, Fucus vesiculosus, Fucus serratus, and both red algae Chondrus crispus and Delesseria sanguinea. Laminariales were found to be the strongest I(2) emitters. Time series of the iodine release of Laminaria digitata and Laminaria hyperborea showed a strong initial I(2) emission when first exposed to air followed by an exponential decline of the release rate. For both species, I(2) emission bursts were observed. For Laminaria saccharina und F. serratus, a more continuous I(2) release profile was detected, however, F. serratus released much less I(2). A. nodosum and F. vesiculosus showed a completely different emission behavior. The I(2) emission rates of these species were slowly increasing with time during the first 1 to 2 h until a more or less stable I(2) emission rate was reached. The lowest I(2) emission rates were detected for the red algae C. crispus and D. sanguinea. Total iodocarbon emission rates showed almost the same general trend, however, the total iodocarbon emission rates were about one to two orders of magnitude lower than those of molecular iodine, demonstrating that I(2) is the major iodine containing volatile released by the investigated seaweed species. In addition, a clear dependency of iodocarbon emission from the ozone level (0-150 ppb O(3)) was found for L. digitata. PMID:22227744

Kundel, Michael; Thorenz, Ute R; Petersen, Jan H; Huang, Ru-Jin; Bings, Nicolas H; Hoffmann, Thorsten

2012-01-08

191

Cooling of highly-charged, short-lived ions for precision mass spectrometry at TRIUMF's Ion Trap for Atomic and Nuclear Science  

NASA Astrophysics Data System (ADS)

At TRIUMF's Ion Trap for Atomic and Nuclear Science (TITAN), masses of short-lived nuclides are measured accurately and precisely using Penning trap mass spectrometry. The achievable precision is primarily limited by the radioactive lifetime of the nuclides. To boost the precision TITAN has demonstrated that short-lived isotopes can be charge-bred to higher charge states within 10-100 s of ms using an electron beam ion trap. The charge breeding process increases the energy spread of the ions, which in turn affects the precision and the efficiency. A novel cooler Penning trap (CPET) has been developed to trap and cool highly-charged ions using electrons prior to the precision measurement. A discussion of electron cooling and the current status of CPET will be given.

Schultz, B. E.; Chowdhury, U.; Simon, V. V.; Andreoiu, C.; Chaudhuri, A.; Gallant, A. T.; Kwiatkowski, A. A.; Macdonald, T. D.; Simon, M. C.; Dilling, J.; Gwinner, G.

2013-09-01

192

Comment on 'Electron-induced bond breaking at low energies in HCOOH and glycine: The role of very short-lived {sigma}* anion states'  

SciTech Connect

Recent model calculations by Gallup et al. [Phys. Rev. A79, 042710 (2009)] suggest that low-energy dissociative electron attachment to formic acid can be explained solely in terms of a very short-lived {sigma}* anion state and that no {sigma}*/{pi}* coupling is required. We argue that this interpretation of the experimental data, which is at odds with our earlier study, is flawed.

Rescigno, T. N. [Lawrence Berkeley National Laboratory, Chemical Sciences, Berkeley, California 94720 (United States); Trevisan, C. S. [California Maritime Academy, Vallejo, California 94590 (United States); Orel, A. E. [Department of Applied Science, University of California, Davis, California 95616 (United States)

2009-10-15

193

SProtP: A Web Server to Recognize Those Short-Lived Proteins Based on Sequence-Derived Features in Human Cells  

Microsoft Academic Search

Protein turnover metabolism plays important roles in cell cycle progression, signal transduction, and differentiation. Those proteins with short half-lives are involved in various regulatory processes. To better understand the regulation of cell process, it is important to study the key sequence-derived factors affecting short-lived protein degradation. Until now, most of protein half-lives are still unknown due to the difficulties of

Xiaofeng Song; Tao Zhou; Hao Jia; Xuejiang Guo; Xiaobai Zhang; Ping Han; Jiahao Sha

2011-01-01

194

Neutron Activation analysis for Dy, Hf, Rb, Sc and Se in some Ghanaian cereals and vegetables using short-lived nuclides and Compton suppression spectrometry  

Microsoft Academic Search

A pseudo-cyclic instrumental neutron activation analysis (PCINAA) method has been developed to determine selected elements in various types of cereal and vegetable from Ghana using relatively short-lived nuclides (t1\\/2<80s) and the Compton suppression counting. The samples were irradiated for 10s at the Dalhousie University SLOWPOKE-2 research reactor facility (DUSR) and allowed to decay for 20s, and counted for 40s. The

B. J. B. Nyarko; E. H. K. Akaho; J. J. Fletcher; A. Chatt

2008-01-01

195

Asymptotic Giant Branch stars as a source of short-lived radioactive nuclei in the solar nebula  

NASA Astrophysics Data System (ADS)

We carried out a theoretical evaluation of the contribution of Asymptotic Giant Branch (AGB) stars to some short-lived (106 less than or equal to Tau-bar less than or equal to 2 x 107 yr) isotopes in the Interstellar Medium (ISM) and in the early solar system using stellar model calculations for thermally pulsing evolutionary phases of low-mass stars. The yields of s-process nuclei in the convective He-shell for different neutron exposures tau0 were obtained, and AGB stars were shown to produce several radioactive nuclei (especially Pd-107, Pb-205, Fe-60, Zr-93, Tc-99, Cs-135, and Hf-182) in diferent amounts. Assuming either contamination of the solar nebula from a single AGB star or models for continuous injection and mixing from many stars into the ISM, we calculate the ratios of radioactive to stable nuclei at the epoch of the Sun's formation. The dilution factor between the AGB ejecta and the early solar system matter is obtained by matching the observed Pd-107/Pd-108 and depends on the value of tau0. It is found that small masses MHe of He-shell material (10-4-10-7 solar mass) enriched in s-process nuclei are sufficient to contaminate 1 solar mass of the ISM to produce the Pd-107 found in the early solar system. Predictions are made for all of the other radioactive isotopes. The optimal model to explain several observed radioactive species at different states of the proto-solar nebula involves a single AGB star with a low neutron exposure (tau0 = 0.03 mbarn-1) which contaminated the cloud with a dilution factor of MHe/solar mass approximately 1.5 x 10-4. This will also contribute newly synthesized stable s-process nuclei in the amount of approximately 10-4 of their abundances already present in the proto-solar cloud. Variations in the degree of homogenization (approximately 30%) of the injected material may account for some of the small general isotopic anomalies found in meteorites. It is also found that Fe-60 is produced in small but significant quantities that may be sufficient to explain the observations if the time elapsed delta from the contamination of the ISM to the formation of protoplanetary bodies is not higher than delta = 5 x 106 yr. If delta is longer, up to 10 x 106 yr, this would require the single AGB star to experience enhanced neutron densities (nn approximately 3 x 109n/cu cm) in the s-processing zone in order to compensate for the branching at Fe-59. The alternative model of long-term continuous ejection of matter from many AGB stars does not appear to match the observations. We also estimate the Al-26 production from the H-shell and find that the Al-26 abundance in the early solar system may be readily explained in a self-consistent manner. Moreover, Al-26 from AGB stars may contribute substantially to the galactic Al-26 gamma-source, while no significant gamma-flux from Co-60 (deriving from Fe-60 decay) is to be expected.

Wasserburg, G. J.; Busso, M.; Gallino, R.; Raiteri, C. M.

1994-03-01

196

A High-Throughput Screen for Alpha Particle Radiation Protectants  

PubMed Central

Abstract Alpha-particle-emitting elements are of increasing importance as environmental and occupational carcinogens, toxic components of radiation dispersal devices and accidents, and potent therapeutics in oncology. Alpha particle radiation differs from radiations of lower linear energy transfer in that it predominantly damages DNA via direct action. Because of this, radical scavengers effective for other radiations have had only limited effect in mitigating alpha particle toxicity. We describe here a simple assay and a pilot screen of 3,119 compounds in a high-throughput screen (HTS), using the alpha-particle-emitting isotope, 225Ac, for the discovery of compounds that might protect mammalian cells from alpha particles through novel mechanisms. The assay, which monitored the viability of a myeloid leukemic cell line upon alpha particle exposure, was robust and reproducible, yielding a Z' factor of 0.66 and a signal-to-noise ratio of nearly 10 to 1. Surprisingly, 1 compound emerged from this screen, epoxy-4,5-?-dihydroxysantonin (EDHS), that showed considerable protective activity. While the value of EDHS remains to be determined, its discovery is a proof of concept and validation of the utility of this HTS methodology. Further application of the described assay could yield compounds useful in minimizing the toxicity and carcinogenesis associated with alpha particle exposure.

Seideman, Jonathan H.; Shum, David; Djaballah, Hakim

2010-01-01

197

Freshly induced short-lived gamma-ray activity as a measure of fission rates in lightly re-irradiated spent fuel  

NASA Astrophysics Data System (ADS)

A new measurement technique has been developed to determine fission rates in burnt fuel, following re-irradiation in a zero-power research reactor. The development has been made in the frame of the LIFE@PROTEUS program at the Paul Scherrer Institute, which aims at characterizing the interfaces between fresh and highly burnt fuel assemblies in modern LWRs.To discriminate against the high intrinsic gamma-ray activity of the burnt fuel, the proposed measurement technique uses high-energy gamma-rays, above 2000 keV, emitted by short-lived fission products freshly produced in the fuel. To demonstrate the feasibility of this technique, a fresh UO2 sample and a 36 GWd/t burnt UO2 sample were irradiated in the PROTEUS reactor and their gamma-ray activities were recorded directly after irradiation.For both fresh and the burnt fuel samples, relative fission rates were derived for different core positions, based on the short-lived 142La (2542 keV), 89Rb (2570 keV), 138Cs (2640 keV) and 95Y (3576 keV) gamma-ray lines. Uncertainties on the inter-position fission rate ratios were mainly due to the uncertainties on the net-area of the gamma-ray peaks and were about 1-3% for the fresh sample, and 3-6% for the burnt one. Thus, for the first time, it has been shown that the short-lived gamma-ray activity, induced in burnt fuel by irradiation in a zero-power reactor, can be used as a quantitative measure of the fission rate. For both fresh and burnt fuel, the measured results agreed, within the uncertainties, with Monte Carlo (MCNPX) predictions.

Krhnert, H.; Perret, G.; Murphy, M. F.; Chawla, R.

2010-12-01

198

Climate response to projected changes in short-lived species under an A1B scenario from 2000-2050 in the GISS climate model  

SciTech Connect

We investigate the climate forcing from and response to projected changes in short-lived species and methane under the A1B scenario from 2000-2050 in the GISS climate model. We present a meta-analysis of new simulations of the full evolution of gas and aerosol species and other existing experiments with variations of the same model. The comparison highlights the importance of several physical processes in determining radiative forcing, especially the effect of climate change on stratosphere-troposphere exchange, heterogeneous sulfate-nitrate-dust chemistry, and changes in methane oxidation and natural emissions. However, the impact of these fairly uncertain physical effects is substantially less than the difference between alternative emission scenarios for all short-lived species. The net global mean annual average direct radiative forcing from the short-lived species is .02 W/m{sup 2} or less in our projections, as substantial positive ozone forcing is largely offset by negative aerosol direct forcing. Since aerosol reductions also lead to a reduced indirect effect, the global mean surface temperature warms by {approx}0.07 C by 2030 and {approx}0.13 C by 2050, adding 19% and 17%, respectively, to the warming induced by long-lived greenhouse gases. Regional direct forcings are large, up to 3.8 W/m{sup 2}. The ensemble-mean climate response shows little regional correlation with the spatial pattern of the forcing, however, suggesting that oceanic and atmospheric mixing generally overwhelms the effect of even large localized forcings. Exceptions are the polar regions, where ozone and aerosols may induce substantial seasonal climate changes.

Menon, Surabi; Shindell, Drew T.; Faluvegi, Greg; Bauer, Susanne E.; Koch, Dorothy M.; Unger, Nadine; Menon, Surabi; Miller, Ron L.; Schmidt, Gavin A.; Streets, David G.

2007-03-26

199

First results using a new technology for measuring masses of very short-lived nuclides with very high accuracy: The MISTRAL program at ISOLDE  

SciTech Connect

MISTRAL is an experimental program to measure masses of very short-lived nuclides (T{sub 1/2} down to a few ms), with a very high accuracy (a few 10{sup -7}). There were three data taking periods with radioactive beams and 22 masses of isotopes of Ne, Na, Mg, Al, K, Ca, and Ti were measured. The systematic errors are now under control at the level of 8x10{sup -7}, allowing to come close to the expected accuracy. Even for the very weakly produced {sup 30}Na (1 ion at the detector per proton burst), the final accuracy is 7x10{sup -7}.

Monsanglant, C.; Audi, G.; Conreur, G.; Cousin, R.; Doubre, H.; Jacotin, M.; Henry, S.; Kepinski, J.-F.; Lunney, D.; Saint Simon, M. de; Thibault, C. [CSNSM-IN2P3-CNRS bat 108, F-91405 Orsay-campus (France); Toader, C. [CSNSM-IN2P3-CNRS bat 108, F-91405 Orsay-campus (France); Inst. Atomic Physics, Bucharest (Romania); Bollen, G.; Lebee, G.; Scheidenberger, C. [CERN, EP Division, Geneva (Switzerland); Borcea, C.; Duma, M. [Inst. Atomic Physics, Bucharest (Romania); Kluge, H.-J. [GSI, D-64291 Darmstadt (Germany); Le Scornet, G. [CSNSM-IN2P3-CNRS bat 108, F-91405 Orsay-campus (France); CERN, EP Division, Geneva (Switzerland)

1999-11-16

200

Bromine and iodine chemistry in a global chemistry-climate model: description and evaluation of very short-lived oceanic sources  

Microsoft Academic Search

The global chemistry-climate model CAM-Chem has been extended to incorporate an expanded bromine and iodine chemistry scheme that includes natural oceanic sources of very short-lived (VSL) halocarbons, gas-phase photochemistry and heterogeneous reactions on aerosols. Ocean emissions of five VSL bromocarbons (CHBr3, CH2Br2, CH2BrCl, CHBrCl2, CHBr2Cl) and three VSL iodocarbons (CH2ICl, CH2IBr, CH2I2) have been parameterised by a biogenic chlorophyll-a (chl-a)

C. Ordez; J.-F. Lamarque; S. Tilmes; D. E. Kinnison; E. L. Atlas; D. R. Blake; G. Sousa Santos; G. Brasseur; A. Saiz-Lopez

2011-01-01

201

Clinical Experience with ?-Particle-Emitting 211At: Treatment of Recurrent Brain Tumor Patients with 211At-Labeled Chimeric Antitenascin Monoclonal Antibody 81C6  

PubMed Central

?-Particleemitting radionuclides, such as 211At, with a 7.2-h half-life, may be optimally suited for the molecularly targeted radiotherapy of strategically sensitive tumor sites, such as those in the central nervous system. Because of the much shorter range and more potent cytotoxicity of ?-particles than of ?-particles, 211At-labeled agents may be ideal for the eradication of tumor cells remaining after surgical debulking of malignant brain tumors. The main goal of this study was to investigate the feasibility and safety of this approach in patients with recurrent malignant brain tumors. Methods Chimeric antitenascin monoclonal antibody 81C6 (ch81C6) (10 mg) was labeled with 71347 MBq of 211At by use of N-succinimidyl 3-[211At]astatobenzoate. Eighteen patients were treated with 211At-labeled ch81C6 (211At-ch81C6) administered into a surgically created resection cavity (SCRC) and then with salvage chemotherapy. Serial ?-camera imaging and blood sampling over 24 h were performed. Results A total of 96.7% 3.6% (mean SD) of 211At decays occurred in the SCRC, and the mean blood-pool percentage injected dose was ?0.3. No patient experienced dose-limiting toxicity, and the maximum tolerated dose was not identified. Six patients experienced grade 2 neurotoxicity within 6 wk of 211At-ch81C6 administration; this neurotoxicity resolved fully in all but 1 patient. No toxicities of grade 3 or higher were attributable to the treatment. No patient required repeat surgery for radionecrosis. The median survival times for all patients, those with glioblastoma multiforme, and those with anaplastic astrocytoma or oligodendroglioma were 54, 52, and 116 wk, respectively. Conclusion This study provides proof of concept for regional targeted radiotherapy with 211At-labeled molecules in oncology. Specifically, the regional administration of 211At-ch81C6 is feasible, safe, and associated with a promising antitumor benefit in patients with malignant central nervous system tumors.

Zalutsky, Michael R.; Reardon, David A.; Akabani, Gamal; Coleman, R. Edward; Friedman, Allan H.; Friedman, Henry S.; McLendon, Roger E.; Wong, Terence Z.; Bigner, Darell D.

2010-01-01

202

Coronaviruses Hijack the LC3-I-positive EDEMosomes, ER-derived vesicles exporting short-lived ERAD regulators, for replication.  

PubMed

Coronaviruses (CoV), including SARS and mouse hepatitis virus (MHV), are enveloped RNA viruses that induce formation of double-membrane vesicles (DMVs) and target their replication and transcription complexes (RTCs) on the DMV-limiting membranes. The DMV biogenesis has been connected with the early secretory pathway. CoV-induced DMVs, however, lack conventional endoplasmic reticulum (ER) or Golgi protein markers, leaving their membrane origins in question. We show that MHV co-opts the host cell machinery for COPII-independent vesicular ER export of a short-living regulator of ER-associated degradation (ERAD), EDEM1, to derive cellular membranes for replication. MHV infection causes accumulation of EDEM1 and OS-9, another short-living ER chaperone, in the DMVs. DMVs are coated with the nonlipidated LC3/Atg8 autophagy marker. Downregulation of LC3, but not inactivation of host cell autophagy, protects cells from CoV infection. Our study identifies the host cellular pathway hijacked for supplying CoV replication membranes and describes an autophagy-independent role for nonlipidated LC3-I. PMID:20542253

Reggiori, Fulvio; Monastyrska, Iryna; Verheije, Monique H; Cal, Tito; Ulasli, Mustafa; Bianchi, Siro; Bernasconi, Riccardo; de Haan, Cornelis A M; Molinari, Maurizio

2010-06-25

203

Mean Ages and Age Spectra for the Tropical Tropopause Layer From Observations of CO2: Implications for Air Transport and Distributions of Short-Lived Chemical Species  

NASA Astrophysics Data System (ADS)

We present extensive CO2 observations of the TTL as related to the characteristics of TTL structure and transport. The results from the CR-AVE and TC4 missions show that air entering the upper TTL above ~360K retains imprint of the global seasonal cycle derived from the well-measured CO2 at the surface, suggesting that data for CO2 can be used as a principal tool to infer the mean age and age spectrum for the TTL, as in the lower stratosphere (Andrews et al., 2001a, 2001b; Boering et al., 1996; Park et al., 2007). The transport rates in the upper TTL inferred from CO2 are applied to generate vertical distributions in the TTL of short-lived organic halogens, non-methane hydrocarbons and alkyl nitrates, which have potentially major impacts on stratospheric ozone and humidity. New data from the Whole Air Sampler obtained over Central America in August, 2007 demonstrate that direct inputs of these transient tracers are largely limited to altitudes ~2 km below the tropical tropopause, and reactive species are efficiently removed with local lifetimes less than or comparable to the mean age of air in the upper TTL (i.e., ranging from a few days to several months). Interestingly, the observations in the subtropical lowermost stratosphere reveal higher concentrations of these species than at the same isentropic level of the TTL, indicating direct loading by summertime midlatitude convection as one of input pathways of these short-lived species into the stratosphere.

Park, S.; Atlas, E. L.; Jimenez, R.; Daube, B. C.; Gottlieb, E.; Nan, J.; Pfister, L.; Conway, T. J.; Bui, T. P.; Gao, R.; Wofsy, S. C.

2008-12-01

204

Mitochondrial mutations and aging: random drift is insufficient to explain the accumulation of mitochondrial deletion mutants in short-lived animals.  

PubMed

Mitochondrial DNA deletions accumulate over the life course in post-mitotic cells of many species and may contribute to aging. Often a single mutant expands clonally and finally replaces the wild-type population of a whole cell. One proposal to explain the driving force behind this accumulation states that random drift alone, without any selection advantage, is sufficient to explain the clonal accumulation of a single mutant. Existing mathematical models show that such a process might indeed work for humans. However, to be a general explanation for the clonal accumulation of mtDNA mutants, it is important to know whether random drift could also explain the accumulation process in short-lived species like rodents. To clarify this issue, we modelled this process mathematically and performed extensive computer simulations to study how different mutation rates affect accumulation time and the resulting degree of heteroplasmy. We show that random drift works for lifespans of around 100 years, but for short-lived animals, the resulting degree of heteroplasmy is incompatible with experimental observations. PMID:23742009

Kowald, Axel; Kirkwood, Thomas B L

2013-06-07

205

Gold-195m, a new generator-produced short-lived radionuclide for sequential assessment of ventricular performance by first pass radionuclide angiocardiography. [Dogs  

SciTech Connect

The feasibility of performing rapid sequential first pass radionuclide angiocardiography using a new short-lived radiotracer, gold-195m (/sup 195//sup m/Au) half-life 30.5 seconds) was evaluated. This radionuclide emits a 262 keV gamma ray and is the daughter of mercury-195 (/sup 195//sup m/Hg) (half-life 41.6 hours). The prototype table top /sup 195//sup m/Hg//sup 195//sup m/Au generator produced 20 to 25 mCi of /sup 195//sup m/Au in 2 ml of eluate (yield of 40 percent). Four dogs each had 15 to 20 sequential first pass studies performed with /sup 195//sup m/Hg at 3 to 10 minute intervals using a computerized multicrystal gamma camera. During the left ventricular phase, 160,000 to 190,000 counts/s were acquired. The end-diastolic left ventricular region of interest contained 3000 to 6000 counts (background- and decay-corrected). Multiple reproducible values for left ventricular ejection fraction were obtained during stable conditions. During infusion of isoproterenol, rapid increase of left ventricular ejection fraction was demonstrated. Excellent agreement was observed between studies performed with technetium-99m diethylenetriaminepentaacetic acid (/sup 99//sup m/Tc-DTPA) and /sup 195//sup m/Au. This new short-lived radiotracer makes possible rapid sequential assessments of ventricular function at greatly reduced patient exposure to radiation.

Wackers, F.J.; Giles, R.W.; Hoffer, P.B.; Lange, R.C.; Berger, H.J.; Zaret, B.L.

1982-07-01

206

Development of radioactive ion beam production systems for Tokai Radioactive Ion Acceleration Complex-High temperature ion source for short-lived isotopes  

NASA Astrophysics Data System (ADS)

We have developed a new ion source system in the isotope separator on-line at Japan Atomic Energy Agency, for separation of short-lived isotopes produced by proton-induced fission of 238U. The ion source system is a forced electron beam induced arc discharge version E type ion source with a target container. We successfully operated this system at 2000 C as a result of reductions in volume of the ion source and the target container, introduction of heating method by electron bombardment, and improvement to the heat shield. This new ion source system was tested using 238U of 640 mg/cm2 with a proton primary beam of 30 MeV, 350 nA. Release times were measured for Kr, In, and Xe. The values of release times are 2.6 s for Kr, 1.8 s for In, and 4.6 s for Xe. In this work, the ion source system enabled us to mass-separate short-lived isotopes such as 93Kr(T1/2=1.286 s), 129In(T1/2=0.61 s), and 141Xe(T1/2=1.73 s) with intensity of 103 ions/s.

Otokawa, Y.; Osa, A.; Sato, T. K.; Matsuda, M.; Ichikawa, S.; Jeong, S. C.

2010-02-01

207

Coactivation of human alpha1- and alpha2-globin genes in single induced MEL cells containing one human alpha-globin locus.  

PubMed

We developed a reverse-transcription polymerase chain reaction assay, performed on single isolated cells, to demonstrate the coexpression of human alpha1- and alpha2-globin mRNA in induced mouse erythroleukemic cells containing a single human alpha-globin locus. These results indicate that both alpha1 and alpha2 genes are activated from the same alpha-globin gene locus implying that HS-40-dependent transcriptional activation is mediated, either by a simultaneous interaction of HS-40 with both a alpha1 and alpha2-globin gene promoters, or by a dynamic process characterized by alternative, but short-lived, interactions with each alpha-globin gene promoter. PMID:9177480

Espret, C; Starck, J; Godet, J; Morl, F

1997-05-01

208

Osteosarcoma risk after simultaneous incorporation of the long-lived radionuclide sup 227 Ac and the short-lived radionuclide sup 227 Th  

SciTech Connect

The effect of injection of 1.85 kBq/kg of the long-lived radionuclide {sup 227}Ac on the induction of osteosarcomas in female NMRI mice by different dose levels (18.5, 74, and 185 kBq/kg) of the short-lived radionuclide {sup 227}Th was investigated. The highest absolute osteosarcoma incidence was observed with the highest doses of {sup 227}Th. Addition of {sup 227}Ac resulted in an additional osteosarcoma incidence only at the lowest dose of {sup 227}Th and did not affect the osteosarcoma incidence resulting from higher doses of {sup 227}Th. The longest times to tumor appearance were observed with {sup 227}Ac alone. The latent period in two different age groups (4 weeks and 10-12 weeks) appeared to be similar following injection with combined doses of {sup 227}Th and {sup 227}Ac but different after injection of each radionuclide alone.

Mueller, W.A.M.; Murray, A.B.; Linzner, U.; Luz, A. (GSF-Institut fuer Pathologie, Neuherberg (Germany, F.R.))

1990-01-01

209

First Results Using a New Technology for Measuring Masses of Very Short-Lived Nuclides with Very High Accuracy: the MISTRAL Program at ISOLDE  

SciTech Connect

MISTRAL is an experimental program to measure masses of very short-lived nuclides (T{sub 1/2} down to a few ms), with a very high accuracy (a few 10{sup -7}). There were three data taking periods with radioactive beams and 22 masses of isotopes of Ne, Na{clubsuit}, Mg, Al{clubsuit}, K, Ca, and Ti were measured. The systematic errors are now under control at the level of 8x10{sup -7}, allowing to come close to the expected accuracy. Even for the very weakly produced {sup 30}Na (1 ion at the detector per proton burst), the final accuracy is 7x10{sup -7}.

C. Monsanglant; C. Toader; G. Audi; G. Bollen; C. Borcea; G. Conreur; R. Cousin; H. Doubre; M. Duma; M. Jacotin; S. Henry; J.-F. Kepinski; H.-J. Kluge; G. Lebee; G. Le Scornet; D. Lunney; M. de Saint Simon; C. Scheidenberger; C. Thibault

1999-12-31

210

Activation cross-section measurements for producing short-lived nuclei with 14 MeV neutronsGe, Pd, Yb  

NASA Astrophysics Data System (ADS)

Activation cross sections for 70Ge(n,p)70Ga, 74Ge(n,p)74Ga, 108Pd(n,p)108Rh, 110Pd(n,?)107Ru, and 174Yb(n,p)174Tm reactions producing short-lived nuclei with half-lives of several minutes were measured in the energy between 13.5 and 14.8 MeV using activation technique in this work. All cross-section values were relatively obtained on the basis of the standard cross section of 93Nb(n,2n)92Nb or 27Al(n,?)24Na, and the neutron energies were measured by the method of cross-sectional ratios for 90Zr(n,2n)89Zr to 93Nb(n,2n)92Nb reactions. Careful attention on corrections was paid to neutron irradiation and induced activities measurement. The measured results were discussed and compared with the previous works.

Lan, Chang-Lin; Fang, Kai-Hong; Xu, Xiao-San; Wang, Qi; Kong, Xiang-Zhong; Liu, Rong; Jiang, Li

2008-07-01

211

Neutron activation analysis for Dy, Hf, Rb, Sc and Se in some Ghanaian cereals and vegetables using short-lived nuclides and Compton suppression spectrometry.  

PubMed

A pseudo-cyclic instrumental neutron activation analysis (PCINAA) method has been developed to determine selected elements in various types of cereal and vegetable from Ghana using relatively short-lived nuclides (t1/2<80 s) and the Compton suppression counting. The samples were irradiated for 10 s at the Dalhousie University SLOWPOKE-2 research reactor facility (DUSR) and allowed to decay for 20 s, and counted for 40 s. The process is repeated every 50 s for 4 cycles to quantify Dy, Hf, Rb, Sc and Se through 165mDy, 179Hf, 86mRb, 46mSc, and 77mSe. The detection limits were generally of the order of 1.0 ng g(-1) except for Rb which is about 1 microg g(-1). Both precision and accuracy of the method were found to be good. PMID:18424050

Nyarko, B J B; Akaho, E H K; Fletcher, J J; Chatt, A

2007-10-12

212

Measurement of Radon Progeny Concentrations in Air by alpha-Particle Spectrometey.  

National Technical Information Service (NTIS)

A technique is presented for measuring air concentrations of the short-lived progeny of radon-222 by the use of alpha spectrometry. In this technique, the concentration of RaA, RaB, and RaC are calculated from one integral count of the RaA and two integra...

G. D. Kerr

1975-01-01

213

Composition and Trends of Short-Lived Trace Gases in the UT/LS over Europe Observed by the CARIBIC Aircraft  

NASA Astrophysics Data System (ADS)

The CARIBIC project (Civil Aircraft for the Regular Investigation of the atmosphere Based on an Instrument Container) involves the monthly deployment of an instrument container equipped to make atmospheric measurements from aboard a commercial airliner, and has operated since 2005 from aboard a Lufthansa Airbus 340-600 . Measurements from the container include in-situ trace gas and aerosol analyses and the collection of aerosol and whole air samples for post-flight laboratory analysis. Measurements made from the sampling flasks include greenhouse gas (GHG), halocarbon and nonmethane hydrocarbon (NMHC) analysis. CARIBIC flights originate in Frankfurt, Germany with routes to India, East Asia, South America, North America and Africa, and typical aircraft cruising altitudes of 10-12km allow for the monitoring of the upper troposphere/lower stratosphere (UT/LS) along these routes. Data collected during the aircrafts departure from and return to Frankfurt provide a 4 year time series of near-monthly measurements of the composition of the UT/LS above Europe. Here we present a discussion of the composition of short-lived trace gases in the whole air samples collected above Europe during CARIBIC flights. Over 150 air samples were collected between May 2005 and July 2009, or about 4 samples per month. Of the whole air samples collected, about 45% showed influence by stratospheric air (i.e. very low values of GHG, NMHC and halocarbons, elevated O3, high potential vorticity). The remaining samples were representative of the upper troposphere; back trajectories for these samples indicate that a little over half were collected in air masses that had been in the boundary layer within the previous 8 days. The predominant source regions for these samples were the Gulf of Mexico and continental North America. Owing to their wide range of chemical lifetimes and the varying composition of emissions, short-lived trace gases transported to the UT/LS can be useful indicators of source region, photochemical processing and transport timescales of an air mass. Seasonal and longer-term trends in trace gases and trace gas composition are discussed, as well as composition of air masses having different origins. Additionally, we apply relationships between the different species, particularly the NMHC, to gain a qualitative understanding of photochemical processes occurring during transport from the boundary layer to the upper troposphere over Europe.

Baker, A. K.; Brenninkmeijer, C. A.; Oram, D. E.; O'Sullivan, D. A.; Slemr, F.; Schuck, T. J.

2009-12-01

214

/sup 195m/Au, a new generator-produced short-lived radionuclide for sequential assessment of ventricular performance by first pass radionuclide angiocardiography  

SciTech Connect

The feasibility of performing rapid sequential first pass radionuclide angiocardiography using a new short-lived radiotracer, (/sup 195/mAu) half-life 30.5 seconds) was evaluated. This radionuclide emits a 262 keV gamma ray and is the daughter of (/sup 195/mHg) (half-life 41.6 hours). The prototype tabletop /sup 195/mHg//sup 195/mAu generator produced 20 to 25 mCi of /sup 195/mAu in 2 ml of eluate (yield of 40 percent). The breakthrough of /sup 195/mHg in the eluate was 0.02 percent of the amount of /sup 195/mHg in the generator. The eluate contained 20 microCi of /sup 195/mHg per study, resulting in an estimated human radiation dose of 0.007 rad/study to the whole body and 0.34 rad/study to the kidney. Four dogs each had 15 to 20 sequential first pass studies performed with /sup 1195/mHg at 3 to 10 minute intervals using a computerized multicrystal gamma camera. During the left ventricular phase, 160,000 to 190,000 counts/s were acquired. The end-diastolic left ventricular region of interest contained 3,000 to 6,000 counts (background- and decay-corrected). Multiple reproducible values for left ventricular ejection fraction were obtained during stable conditions. The mean (+/- standard deviation) interstudy variability was 4 +/- 2 percent. During infusion of isoproterenol, rapid increase of left ventricular ejection fraction was demonstrated. Excellent agreement was observed between studies performed with /sup 99m/Tc-DTPA) and /sup 195/mAu. The mean interstudy difference was 4 +/- 3 percent. Thus, sufficiently high yield and dose are obtained from the /sup 195/mHg//sup 195/mAu generator for reliable high count rate first pass determination of left ventricular ejection fraction. This new short-lived radiotracer makes possible rapid sequential assessments of ventricular function at greatly reduced patient exposure to radiation.

Wackers, F.J.; Giles, R.W.; Hoffer, P.B.; Lange, R.C.; Berger, H.J.; Zaret, B.L.

1982-07-01

215

Increased Concentrations of Short-Lived Decay-Series Radionuclides in Groundwaters Underneath the Nopal I Uranium Deposit at Pena Blanca, Mexico  

NASA Astrophysics Data System (ADS)

The Nopal I uranium ore deposit at Pena Blanca, Mexico, located at > 200 meters above the groundwater table, provides an ideal natural analog for quantifying the effectiveness of geological barrier for isolation of radioactive waste nuclides from reaching the human environments through ground water transport. To fulfill such natural analog studies, three wells (PB1, PB2, and PB3 respectively) were drilled at the site from the land surface down to the saturated groundwater zone and ground waters were collected from each of these wells through large- volume sampling/in-situ Mn-filter filtration for analyses of short-lived uranium/thorium-series radionuclides. Our measurements from PB1 show that the groundwater standing in the hole has much lower 222Rn activity than the freshly pumped groundwater. From this change in 222Rn activity, we estimate the residence time of groundwater in PB1 to be about 20 days. Our measurements also show that the activities of short-lived radioisotopes of Th (234Th), Ra (228Ra, 224Ra, 223Ra), Rn (222Rn), Pb (210Pb), and Po (210Po) in PB1, PB2, and PB3 are all significantly higher than those from the other wells near the Nopal I site. These high activities provide evidence for the enrichment of long-lived U and Ra isotopes in the groundwater as well as in the associated adsorbed phases on the fractured aquifer rocks underneath the ore deposit. Such enrichment suggests a rapid dissolution of U and Ra isotopes from the uranium ore deposit in the vadose zone and the subsequent migration to the groundwater underneath. A reactive transport model can be established to characterize the in-situ transport of radionuclides at the site. The observed change of 222Rn activity at PB1 also suggests that the measured high radioactivityies in ground waters from the site isare not an artifact of drilling operations. However, further studies are needed to assess if or to what extent the radionuclide migration is affected by the previous mining activities at the site.

Luo, S.; Ku, T.; Todd, V.; Murrell, M. T.; Dinsmoor, J. C.

2007-05-01

216

Some observations on the concentrations of short-lived decay products of radon and thoron in the monsoon rains of Bombay, India  

SciTech Connect

The concentrations of radon decay products /sup 214/Pb(RaB) and /sup 214/Bi(RaC) and thoron daughter /sup 212/Pb(ThB) have been measured in rainfall at Bombay. The presence of short-lived /sup 218/Po(RaA) is indicated in a few samples. The levels of /sup 214/ Pb varied from 300 to 7000 pCi (11-260 Bq) per liter, while the activity ratios of /sup 214/Bi//sup 214/Pb are in the range of 0.5-1.5. From these values of the ratios a cloud drop lifetime, from nucleation to deposition, of 20--60 min is estimated. The concentrations of /sup 212/Pb varied from 2 to 30 pCi (0.075-1.1 Bq) per liter. The levels of radon and thoron daughter products are lower in Bombay summer rainfall compared with other areas due to their reduced concentrations in the maritime monsoon winds. Approximate estimates of scavenging ratios based on the surface air concentrations are 85 +- 65 (1 standard deviation) and 30 +- 20 (1 standard deviation) for radon and thoron daughters, respectively.

Rangarajan, C.; Eapen, C.D.

1985-08-20

217

High viral burden restricts short-lived effector cell number at late times postinfection through increased natural regulatory T cell expansion.  

PubMed

Generating and maintaining a robust CD8(+) T cell response in the face of high viral burden is vital for host survival. Further, balancing the differentiation of effectors along the memory precursor effector cell pathway versus the short-lived effector cell (SLEC) pathway may be critical in controlling the outcome of virus infection with regard to clearance and establishing protection. Although recent studies have identified several factors that have the capacity to regulate effector CD8(+) T cell differentiation-for example, inflammatory cytokines-we are far from a complete understanding of how cells choose the memory precursor effector cell versus SLEC fate following infection. In this study, we have modulated the infectious dose of the poxvirus vaccinia virus as an approach to modulate the environment present during activation and expansion of virus-specific effector cells. Surprisingly, in the face of a high virus burden, the number of SLECs was decreased. This decrease was the result of increased natural regulatory T cells (Tregs) generated by high viral burden, as depletion of these cells restored SLECs. Our data suggest Treg modulation of differentiation occurs via competition for IL-2 during the late expansion period, as opposed to the time of T cell priming. These findings support a novel model wherein modulation of the Treg response as a result of high viral burden regulates late-stage SLEC number. PMID:23589620

Amoah, Samuel; Holbrook, Beth C; Yammani, Rama D; Alexander-Miller, Martha A

2013-04-15

218

Effects of Soy-derived diets on plasma and liver lipids, glucose tolerance, and longevity in normal, long-lived and short-lived mice.  

PubMed

We examined the effects of diets based on a low isoflavone or a high isoflavone soy protein isolates in normal, growth-hormone receptor knockout and Ames dwarf, and Prop 1 (df) mice that are hypoinsulinemic, insulin-sensitive, and exceptionally long-lived, as well as in growth hormone transgenic mice that are hyperinsulinemic, insulin-resistant, dyslipidemic, and short-lived. Soybean diets tended to normalize plasma cholesterol levels in dwarf and transgenic mice, while low isoflavone diet reduced plasma triglycerides in most of the examined genotypes. The effects of low isoflavone and high isoflavone diets on the levels of free and esterified cholesterol in the liver were strongly genotype-dependent. Fasting blood glucose levels were reduced and glucose tolerance improved by both low isoflavone and high isoflavone diets in growth hormone-transgenic mice and in their normal siblings. Glucose tolerance was also improved by high-isoflavone diet in growth hormone receptor knockout mice. Lifespan was increased by low isoflavone diet in normal mice from two of the examined stocks. High isoflavone diet increased lifespan in normal animals from one line, but reduced lifespan of normal mice from a different line. We conclude that dietary soy protein intake can improve plasma and hepatic lipid profiles, reduce fasting glucose, enhance capacity for glucose tolerance, and prolong life, but all of these effects are strongly genotype-dependent. PMID:15326565

Bartke, A; Peluso, M R; Moretz, N; Wright, C; Bonkowski, M; Winters, T A; Shanahan, M F; Kopchick, J J; Banz, W J

2004-08-01

219

Near-infrared laser induced conformational change and UV laser photolysis of glycine in low-temperature matrices: Observation of a short-lived conformer  

NASA Astrophysics Data System (ADS)

The near-infrared spectrum (NIR) of glycine was measured in Ar and Kr matrices. Matrix-isolated glycine was irradiated with NIR laser light at the first OH or NH stretching overtone bands of the three main glycine (ttt/Ip, ccc/IIn, tct/IIIp) conformers. The main conversion paths and their efficiencies are described qualitatively, and it is shown that there are significant differences in the conversion paths in Ar and Kr. In the detailed analysis of these experiments many new, formerly unobserved low-intensity transitions of the three main conformers were identified, and in addition a short-lived (tunneling half-life is 5 2 s) higher energy conformer (ttc/VIp) was observed during the irradiation at the first OH stretching overtone of ttt/Ip. The UV spectrum of glycine was also measured in Ar matrix, and the first two absorption bands of conformers ttt/Ip and ccc/IIn were identified. UV laser irradiation at longer (240 nm) wavelengths promotes rotamerization, while at shorter wavelengths (235 and 213.5 nm) it results in depletion of the different conformers with different rates. Analysis of spectra recorded after UV irradiation showed that the two main photodecomposition processes are decarboxylation and H2O loss, forming methylamine and NH2CHCO, respectively.

Bazs, Gbor; Magyarfalvi, Gbor; Tarczay, Gyrgy

2012-10-01

220

The variation of short-lived NOy species around sunrise at mid-latitudes as measured by MIPAS-B and calculated by KASIMA  

NASA Astrophysics Data System (ADS)

Vertical profiles of total reactive nitrogen (NOy = NO2 + HNO3 + ClONO2 + 2N2O5 + HO2NO2) along with the source gas N2O up to 38 km were retrieved from infrared limb emission spectra measured by the Michelson Interferometer for Passive Atmospheric Sounding, Balloonborne version (MIPAS-B) instrument from Aire sur l'Adour (France, 42N) on April 30, 1999. Three limb sequences of spectra were recorded 1 hour before, at and 3 hours after sunrise, respectively, allowing to investigate the NOy partitioning under night-time and - for the first time with the MIPAS-B instrument - also under day-time conditions and to study the temporal evolution of the short-lived species N2O5 and NO2 around sunrise. The MIPAS-B data are compared to calculations performed with the 3-D chemical transport model KASIMA (Karlsruhe Simulation model of the Middle Atmosphere). This comparison reveals a high degree of confidence in the model for the HNO3/NOy ratio in the whole altitude region and for the N2O5/NOy and NO2/NOy ratios above about 26 km. Below this altitude the N2O5/NOy ratio is significantly underestimated by the model. Also, the MIPAS-B measurement suggests a night-time built up of NO2 which is not reproduced by the model in an altitude region around 22 km.

Stowasser, M.; Oelhaf, H.; Ruhnke, R.; Kleinert, A.; Wetzel, G.; Friedl-Vallon, F.; Kouker, W.; Lengel, A.; Maucher, G.; Nordmeyer, H.; Reddmann, Th.; Fischer, H.

2003-04-01

221

Determination of water ages and flushing rates using short-lived radium isotopes in large estuarine system, the Yangtze River Estuary, China  

NASA Astrophysics Data System (ADS)

We investigated the spatial and temporal distribution of naturally-occurring short-lived radium isotopes (224Ra, t1/2 = 3.6 d and 223Ra, t1/2 = 11 d) to examine coastal water mixing dynamics of the third world largest estuary, Yangtze River Estuary (YRE) during two field trips in April 2010 and May 2011. Distributions of the 224Ra/223Ra activity ratios within the YRE area were used to calculate apparent estuarine water ages. Field-derived results were then compared to hydrodynamic assessments obtained by a Lagrangian particle tracking simulation experiment performed using the Princeton Ocean Model (POM). Water ages obtained via both geotracers and particle tracking agree very well. During both field trips an anomalously "younger" water mass (low salinity and higher radium activities) was observed at about 90-170 km offshore distance from the mouth of the river, suggesting an additional terrestrial water source influenced this area. The temporal distribution of the radium isotopes indicated a semi-diurnal tidal pattern in the YRE with relatively constant isotopic composition of less than a 20% variation during our observations. An integrated water flushing rate based on our observations (excluding the additional anomalous source area) was 8.4 km day-1.

Xu, Bo-Chao; Dimova, Natasha T.; Zhao, Liang; Jiang, Xue-Yan; Yu, Zhi-Gang

2013-04-01

222

Alterations in oxygen consumption, respiratory quotient, and heat production in long-lived GHRKO and Ames dwarf mice, and short-lived bGH transgenic mice.  

PubMed

Growth hormone (GH) signaling influences longevity in mice, with decreased GH signaling associated with longer life span and increased GH signaling with shortened life span. A proposed mechanism through which GH signaling influences life span postulates that decreased GH signaling lowers metabolic rate, thus slowing aging by decreasing production of damaging free radicals. The influence of altered GH signaling on metabolism was tested by monitoring oxygen consumption (VO(2)), respiratory quotient (RQ), and heat production in long-lived GH receptor knockout (GHRKO) and Ames dwarf mice, and short-lived bovine GH-overexpressing transgenic (bGH TG) mice. Intriguingly, both GHRKO and Ames dwarf mice have increased VO(2) and heat per gram body weight, and decreased RQ, whereas bGH TG mice have decreased VO(2) and heat per gram body weight and increased RQ. In conclusion, decreased GH signaling associates with increased metabolism per body weight and may beneficially affect mitochondrial flexibility by increasing the capacity for fat oxidation; generally, GH excess produces opposite metabolic effects. PMID:19286975

Westbrook, Reyhan; Bonkowski, Michael S; Strader, April D; Bartke, Andrzej

2009-03-13

223

Alterations in Oxygen Consumption, Respiratory Quotient, and Heat Production in Long-Lived GHRKO and Ames Dwarf Mice, and Short-Lived bGH Transgenic Mice  

PubMed Central

Growth hormone (GH) signaling influences longevity in mice, with decreased GH signaling associated with longer life span and increased GH signaling with shortened life span. A proposed mechanism through which GH signaling influences life span postulates that decreased GH signaling lowers metabolic rate, thus slowing aging by decreasing production of damaging free radicals. The influence of altered GH signaling on metabolism was tested by monitoring oxygen consumption (VO2), respiratory quotient (RQ), and heat production in long-lived GH receptor knockout (GHRKO) and Ames dwarf mice, and short-lived bovine GH-overexpressing transgenic (bGH TG) mice. Intriguingly, both GHRKO and Ames dwarf mice have increased VO2 and heat per gram body weight, and decreased RQ, whereas bGH TG mice have decreased VO2 and heat per gram body weight and increased RQ. In conclusion, decreased GH signaling associates with increased metabolism per body weight and may beneficially affect mitochondrial flexibility by increasing the capacity for fat oxidation; generally, GH excess produces opposite metabolic effects.

Bonkowski, Michael S.; Strader, April D.; Bartke, Andrzej

2009-01-01

224

Alpha-Particle Angular Distributions of At and Rn Isotopes and Their Relation to Nuclear Structure  

SciTech Connect

We report on an extensive on-line nuclear orientation study of the angular distribution of {alpha} particles emitted in the favored decay of neutron deficient At and Rn nuclei near the {ital N}=126 shell closure. Surprisingly large anisotropies were observed, showing pronounced changes from one isotope to another. Comparing these data with several theoretical models shows that anisotropic {alpha} emission in favored decays from near-spherical nuclei can well be explained within the shell model, implying that it is mainly determined by the structure of the decaying nucleus. {copyright} {ital 1996 The American Physical Society.}

NICOLE Collaboration and ISOLDE Collaboration

1996-12-01

225

Rapid determination of actinides in urine by inductively coupled plasma mass spectrometry and alpha spectrometry: A hybrid approach  

Microsoft Academic Search

A new rapid separation method that allows separation and preconcentration of actinides in urine samples was developed for the measurement of longer lived actinides by inductively coupled plasma mass spectrometry (ICP-MS) and short-lived actinides by alpha spectrometry; a hybrid approach. This method uses stacked extraction chromatography cartridges and vacuum box technology to facilitate rapid separations. Preconcentration, if required, is performed

Sherrod L. Maxwell III; Vernon D. Jones

2009-01-01

226

More evidence for very short-lived substance contribution to stratospheric chlorine inferred from HCl balloon-borne in situ measurements in the tropics  

NASA Astrophysics Data System (ADS)

Volume mixing ratio (vmr) vertical profiles of hydrogen chloride (HCl) are retrieved from in situ measurements performed by a balloon-borne infrared tunable diode laser absorption spectrometer (SPIRALE) during two balloon flights in the tropics (Teresina, Brazil, 5.1 S-42.9 W) in June 2005 and June 2008. HCl vertical profiles obtained from 15 to 31 km are presented and analysed to estimate the contribution of very short-lived substances (VSLS) to total stratospheric chlorine. Both retrieved vertical profiles of HCl from these flights agree very well with each other, with estimated overall uncertainties of 6% on vmr between 23 and 31 km. Upper limits of HCl vmr as low as 20 pptv in June 2008 and 30 pptv in June 2005 are inferred in the upper part of the tropical tropopause layer (TTL). Backward trajectory calculations and such low amounts suggest that the air masses sampled correspond to typical background conditions, i.e. neither influenced by recent tropospheric nor stratospheric air. Taking into account the recently reported VSL source gas measurements obtained in similar conditions (Laube et al., 2008) and the main intermediate degradation product gas COCl2 (Fu et al., 2007), a total VSLS contribution of 8540 pptv to stratospheric chlorine is inferred. This refines the WMO (2007) estimation of 50 to 100 pptv, which was not taking into account any HCl contribution. In addition, comparisons of HCl measurements between SPIRALE and the Aura MLS satellite instrument in the tropical lower and middle stratosphere lead to a very good agreement. The previous agreement between MLS-deduced upper stratospheric total chlorine content and modelled values including 100 pptv of VSLS (Froidevaux et al., 2006) is thus supported by our present result about the VSLS contribution.

Mbarki, Y.; Catoire, V.; Huret, N.; Berthet, G.; Robert, C.; Poulet, G.

2010-01-01

227

More evidence for very short-lived substance contribution to stratospheric chlorine inferred from HCl balloon-borne in situ measurements in the tropics  

NASA Astrophysics Data System (ADS)

Volume mixing ratio (vmr) vertical profiles of hydrogen chloride (HCl) are retrieved from in situ measurements performed by a balloon-borne infrared tunable diode laser absorption spectrometer (SPIRALE) during two balloon flights in the tropics (Teresina, Brazil, 5.1 S-42.9 W) at three year interval in June 2005 and June 2008. HCl vertical profiles obtained from 15.0 to 31.0 km are presented and analysed to estimate the contribution of very short-lived substances (VSLS) to total stratospheric chlorine. Both retrieved vertical profiles of HCl from these flights globally agree very well with each other, with estimated overall uncertainties of 6% on vmr between 23 and 31 km. Upper limits of HCl vmr as low as (2020) pptv in June 2008 and (3030) pptv in June 2005 are inferred in the upper part of the tropical tropopause layer (TTL). Backward trajectory calculations suggest that these low amounts were sampled in air masses corresponding to typical background conditions, i.e. neither influenced by recent tropospheric nor stratospheric air. Taking into account the recently reported VSLS source gas measurements obtained in similar conditions (Laube et al., 2008) and the main intermediate product gas (COCl2), a VSLS contribution of about (8535 pptv) to total stratospheric chlorine is inferred. This refines the WMO (2007) estimation of 50 to 100 pptv, which was not taking into account any HCl contribution. In addition, comparisons of HCl measurements between SPIRALE and MLS-Aura satellite instrument in the tropical lower and middle stratosphere lead to a very good agreement. Since HCl modelled values derived from a total stratospheric chlorine budget including 100 pptv of VSLS agree with MLS measurements in the upper stratosphere, the consistency between SPIRALE and MLS measurements provides another evidence for this VSLS contribution.

Mbarki, Y.; Catoire, V.; Berthet, G.; Huret, N.; Robert, C.

2009-07-01

228

Voltammetric investigation of DNA damage induced by nitrofurazone and short-lived nitro-radicals with the use of an electrochemical DNA biosensor.  

PubMed

Electrochemical behavior of nitrofurazone (NFZ) was investigated with the use of cyclic voltammetry (CV) and differential pulse voltammetry (DPV) methods. The pH-dependence of NFZ was studied at a glassy carbon electrode (GCE) in ethanol/Britton-Robinson buffer (30:70), and short-lived nitro-radicals were generated by the reduction of NFZ at high pHs (>7.0). In the presence of DNA, the DPV peak current of NFZ decreased and the peak potential shifted negatively, which indicated that there was an electrostatic interaction between NFZ and DNA. An electrochemical dsDNA/GCE biosensor was prepared to study the DNA damage produced in the presence NFZ; this process was followed with the use of the Co(phen)(3)(2+) electroactive probe. Also, the oxidation peaks of guanosine (750 mV) and adenosine (980 mV) indicated that DNA damage was related directly to the nitro-radicals. Experiments demonstrated that DNA damage occurred via two different steps while NFZ was metabolized and nitro-radicals were produced. Novel work with AFM on the NFZ/DNA interaction supported the suggestion that in vivo, the nitro-radicals were more cytotoxic than the NFZ molecules. A linear DPV calibration plot was obtained for NFZ analysis at a modified dsDNA/GCE (concentration range: 2.50 10(-6)-3.75 10(-5) mol L(-1); limit of detection: 8.0 10(-7) mol L(-1)), and NFZ was determined successfully in pharmaceutical samples. PMID:22717476

Ni, Yongnian; Wang, Pingping; Kokot, Serge

2012-06-06

229

Concentrated fish oil (Lovaza(R)) extends lifespan and attenuates kidney disease in lupus-prone short-lived (NZBxNZW)F1 mice.  

PubMed

A growing number of reports indicate that anti-inflammatory actions of fish oil (FO) are beneficial against systemic lupus erythematosus (SLE). However, the majority of pre-clinical studies were performed using 5-20% FO, which is higher than the clinically relevant dose for lupus patients. The present study was performed in order to determine the effective low dose of FDA-approved concentrated FO (Lovaza) compared to the commonly used FO-18/12 (18-Eicosapentaenoic acid [EPA]/12-Docosahexaenoic acid [DHA]). We examined the dose-dependent response of Lovaza (1% and 4%) on an SLE mouse strain (NZBxNZW)F1 and compared the same with 1% and 4% placebo, as well as 4% FO-18/12, maintaining standard chow as the control. Results show for the first time that 1% Lovaza extends maximal lifespan (517?d) and 4% Lovaza significantly extends both the median (502?d) and maximal (600?d) life span of (NZBxNZW)F1 mice. In contrast, FO-18/12 extends only median lifespan (410?d) compared to standard chow diet (301?d). Additionally, 4% Lovaza significantly decreased anti-dsDNA antibodies, reduced glomerulonephritis and attenuated lipopolysaccharide-induced pro-inflammatory cytokines (IL-1?, IL-6, TNF-?) in splenocytes compared to placebo. 4% Lovaza was also shown to reduce the expression of inflammatory cytokines, including IL-1?, IL-6 and TNF-?, while increasing renal anti-oxidant enzymes in comparison to placebo. Notably, NF?B activation and p65 nuclear translocation were lowered by 4% Lovaza compared to placebo. These data indicate that 1% Lovaza is beneficial, but 4% Lovaza is more effective in suppressing glomerulonephritis and extending life span of SLE-prone short-lived mice, possibly via reducing inflammation signaling and modulating oxidative stress. PMID:23918873

Halade, Ganesh V; Williams, Paul J; Veigas, Jyothi M; Barnes, Jeffrey L; Fernandes, Gabriel

2013-06-01

230

Evaluation of shelf basin interaction in the western Arctic by use of short-lived radium isotopes: The importance of mesoscale processes  

NASA Astrophysics Data System (ADS)

Shelf basin exchange in the western Arctic was evaluated by use of water-column analyses of 228Ra/226Ra ratios and the first measurements of the short-lived 224Ra (T1/2=3.64 d) in the Arctic. During the 2002 shelf basin interaction (SBI) program, excess 224Ra was detected over the shelf but was not found seaward of the shelf-break. Similarly, the 228Ra/226Ra ratio dropped rapidly from the shelf across the shelf-break. Consequently, the model age gradient (elapsed time since shelf residence) northward across the Chukchi Shelf increased from 1 5 years nearshore to approximately 14 years in surface waters sampled off shelf at the southern margin of the Beaufort Gyre. This steep gradient is consistent with very slow exchange between the Chukchi Shelf and the Beaufort Gyre, whereby Bering Strait inflow is constrained by the Earth's rotation to follow local isobaths and does not easily move into deeper water. The strong dynamic control inhibiting water that enters the system through Bering Strait from flowing north across isobaths also would lead to a long recirculation time of river water emptied into the Beaufort Gyre. Possible mechanisms that can generate cross-shelf currents that break the topographic constraint to follow isobaths, and thereby transport water (and associated properties) off the shelves include wind-induced upwelling/downwelling, meandering jets, and eddies. Evidence of such a process was found during the ICEX project in the Beaufort Sea in April 2003 when excess 224Ra was measured over 200 km from any shelf source. This required an NE offshore flow of 40 cm s-1 assuming that the source water derives from the mouth of Barrow Canyon. A weak northeastward flow was measured using an LADCP within the upper 300 m of the ocean, but was of lower speed than required by the 224Raxs at the time of the ICEX occupation.

Kadko, David; Muench, Robin

2005-12-01

231

A LOWER INITIAL ABUNDANCE OF SHORT-LIVED {sup 41}Ca IN THE EARLY SOLAR SYSTEM AND ITS IMPLICATIONS FOR SOLAR SYSTEM FORMATION  

SciTech Connect

The short-lived radionuclide {sup 41}Ca plays an important role in constraining the immediate astrophysical environment and the formation timescale of the nascent solar system due to its extremely short half-life (0.1 Myr). Nearly 20 years ago, the initial ratio of {sup 41}Ca/{sup 40}Ca in the solar system was determined to be (1.41 {+-} 0.14) Multiplication-Sign 10{sup -8}, primarily based on two Ca-Al-rich Inclusions (CAIs) from the CV chondrite Efremovka. With an advanced analytical technique for isotopic measurements, we reanalyzed the potassium isotopic compositions of the two Efremovka CAIs and inferred the initial ratios of {sup 41}Ca/{sup 40}Ca to be (2.6 {+-} 0.9) Multiplication-Sign 10{sup -9} and (1.4 {+-} 0.6) Multiplication-Sign 10{sup -9} (2{sigma}), a factor of 7-10 lower than the previously inferred value. Considering possible thermal processing that led to lower {sup 26}Al/{sup 27}Al ratios in the two CAIs, we propose that the true solar system initial value of {sup 41}Ca/{sup 40}Ca should have been {approx}4.2 Multiplication-Sign 10{sup -9}. Synchronicity could have existed between {sup 26}Al and {sup 41}Ca, indicating a uniform distribution of the two radionuclides at the time of CAI formation. The new initial {sup 41}Ca abundance is 4-16 times lower than the calculated value for steady-state galactic nucleosynthesis. Therefore, {sup 41}Ca could have originated as part of molecular cloud materials with a free decay time of 0.2-0.4 Myr. Alternative possibilities, such as a last-minute input from a stellar source and early solar system irradiation, could not be definitively ruled out. This underscores the need for more data from diverse CAIs to determine the true astrophysical origin of {sup 41}Ca.

Liu, Ming-Chang [Institute of Astronomy and Astrophysics, Academia Sinica, Taipei, Taiwan (China); Chaussidon, Marc [Centre de Recherches Petrographiques et Geochimiques, CNRS, Nancy (France); Srinivasan, Gopalan [Center for Earth Science, Indian Institute of Science, Bangalore (India); McKeegan, Kevin D., E-mail: mcliu@asiaa.sinica.edu.tw [Department of Earth and Space Sciences, UCLA, Los Angeles, CA (United States)

2012-12-20

232

Instrument for measuring total alpha particle energies of alpha emitters in ambient air  

NASA Astrophysics Data System (ADS)

This paper describes the design, fabrication, testing and evaluation of a self-reading, carbon fiber, electrometer-type instrument. It is used for measuring the total energy of alpha particles emitted in air by progenies of 222Rn (218Po, 214Pb, and 214Bi), and sometimes by other types of alpha emitters (e.g. 212Pb, 238U, and 239Pu). The purpose of these measurements is to assess the energy delivered by alpha emission from these sources to the lung tissue. A sample (charged progenies attached to aerosols) is collected on filter paper from a known volume of air and placed on the instrument. The discharge rate indicates the alpha energy in MeVl-1 of air per min that is produced by the alpha emitters. The calibration procedure shows that the instrument has an energy sensitivity for alpha particles of 800.5MeV/scale unit. The range of the readout scale is 30 units. Measurements of alpha contamination in air were made using this instrument in buildings, private homes and in a standard chamber. The value of the radon concentration in this chamber is traceable back to the US Environmental Protection Agency (EPA) and to the National Institute of Standards and Technology (NIST).

Kronenberg, S.; Brucker, G. J.; Cummings, B.; Bechtel, E.; Gentner, F.; Horne, S.

2000-11-01

233

Constraining the Time-Scale of Interaction of Sea Ice Sediments and Surface Sea Water in the Arctic Ocean Using Short-Lived Radionuclide Tracers  

NASA Astrophysics Data System (ADS)

We measured the activities of short-lived radionuclides (Th-234, Be-7, Po-210, Pb-210, Cs-137, Th-234, Ra-226 and Ra-228) and concentrations of several elements (Be, Pb, Fe, Al, Co, Ni, Cu and Zn) on a suite of ice-rafted sediments (IRS) collected during BERINGIA-2005 in the Western Arctic Ocean. A suite of water samples were also collected and analyzed for particulate and dissolved Be-7, Po-210, Pb-210, Th-234, Ra-226 and Ra-228. The activities of Be-7 and Pb-210 in the IRS are 1-2 orders of magnitude higher than those reported in the source sediments. Presence of excess Th-234 in the IRS indicates that the removal of Th-234 from surface seawater took place on time scales comparable to the mean-life of Th-234. While the Po-210/Pb-210 activity ratios in the source sediments (1.0) and the atmospheric depositional input (~0.1) are known, varying ratios of 0.78 to 1.0 were found in the IRS. This ratio can be utilized to obtain the residence time of the IRS in sea ice. The activity of Ra-226 and Ra-228 in all the IRS is nearly constant (within a factor of 1.6) and are comparable to the benthic sediments in the source region. The activities of atmospherically-delivered radionuclides, Be-7 and Pb-210, in IRS varied by factors of ~4.5 and 9, respectively, and this variation is attributed to differences in the extent of interaction of surface water with IRS and differences in the mean-lives of these nuclides. While significant enrichment of Be-7 and Pb-210 has been found, there is no enrichment of stable Pb or Be. The Al-normalized enrichment factor for elements measured (Co, Ni, Cu, Zn, Pb and Be) indicate that there is no significant enrichment of these elements, with Al-normalized enrichment factors less than 1.3.

Baskaran, M.; Andersson, P. S.; Jweda, J.; Dahlqvist, R.; Ketterer, M. E.

2007-12-01

234

Evidence For Three, Short Lived, Geomagnetic Field Excursions Recorded In Postglacial (9-15,000 YBP) Carbonates Of The Tahitian Coral Reef  

NASA Astrophysics Data System (ADS)

A detailed composite record of inclinations and relative paleointensity for Late Quaternary (8-16,000 YBP) coral-reef framework rocks recovered from the island of Tahiti during IODP Expedition 310 yielded reproducible evidence for three, short-lived magnetic field excursions at 10,700200 YBP, 12,900200 YBP, and 14,200200 YBP. Age estimates for these excursions, which are constrained by more than 250 radiocarbon dates from the same cores, make them younger than any other published well-documented and dated excursion from the continents or the continental margins. Samples for paleomagnetic analysis were recovered mainly from the abundant microbialites deposited in the interstices of the macro-coral framework. These carbonate rocks make up more than 60% of the Tahiti Coral Reef and 95% of all magnetic samples. Initial paleomagnetic and rock magnetic studies showed that the microbialites carry a strong and stable natural magnetic remanence with an average value of -30.6 (?95=2.9) that is not significantly different from Tahiti's expected axial-dipole inclination. Rock magnetic studies indicate that the NRM is carried almost entirely by detrital titanomagnetite grains (<1 ?m to ~20 ?m in grain size) that were derived from the Tahiti volcanic edifice, but the grains were locked-in by biological mediation during biogenic carbonate precipitation. To assess the spatial coherence of the paleomagnetic directions, paleointensities, and the rock magnetic variability of these young excursions, detailed re-sampling of all available material with a clear up-down direction, extending from one normal polarity interval through the recorded excursion to the following normal interval (1m), was undertaken. In total we obtained inclination and relative paleointensity estimates (based on CHI, ARM, and SIRM) from more then 750 samples. General results of this analysis show that these young magnetic excursions are real and reproducible and often associated with paleointensity lows. NRM demagnetization reveals consistent changes in both inclination and occasionally, where we have intervals with sequential samples from unbroken core segments, declination. The duration of these young excursional events is constrained by the bulk framework rock accumulation rate (5-10 m/ky; 100-200 yrs/m) to timescales of 100's of years. These intriguing new observations have profound implications and may change our ideas about the number and frequency of magnetic excursions.

Platzman, E. S.; Lund, S.; Camoin, G.; Thouveny, N.; Scientific Team IODP Expedition 310

2011-12-01

235

Oxygen isotopic and geochemical evidence for a short-lived, high-temperature hydrothermal event in the Chegem caldera, Caucasus Mountains, Russia  

USGS Publications Warehouse

Within the 2.8 Ma Chegem ash-flow caldera (11 ?? 15 km), a single cooling unit of rhyolitic to dacitic welded tuff more than 2 km thick is exposed in deep valleys incised during recent rapid uplift of the Caucasus Mountains. The intracaldera tuff is mineralogically fresh and unaltered, and is overlain by andesite lavas and cut by a resurgent granodiorite intrusion. Major- and trace-element compositions for a 1405-m stratigraphic section of intracaldera tuff display trends of upwardly increasing Na2O, CaO, Al2O3, total Fe, MgO, TiO2, Sr and Zr and decreasing SiO2, K2O and Rb. This mafic-upward zoning (from 76.1 to 69.9% SiO2) reflects an inverted view of the upper part of the source magma chamber. Oxygen isotope studies of 35 samples from this 1405-m section define a striking profile with "normal" igneous ??18O values (+7.0 to +8.5) in the lower 600 m of tuff, much lower ??18O values (-4.0 to +4.3) in a 700-m zone above that and a shift to high ??18O values (+4.4 to -10.9) in the upper 100 m of caldera-fill exposure. Data from two other partial stratigraphic sections indicate that these oxygen isotope systematics are probably a caldera-wide phenomenon. Quartz and feldspar phenocrysts everywhere have "normal" igneous ??18O values of about +8.5 and +7.5, respectively, whereas groundmass and glass ??18O values range from -7.7 to +12.3. Consequently, the ??18O values of coexisting feldspar, groundmass and glass form a steep array in a plot of ??feldspar vs. ??groundmass/glass. Such pronounced disequilibrium between coexisting feldspar and groundmass or glass has never before been observed on this scale. It requires a hydrothermal event involving large amounts of low-18O H2O at sufficiently high temperatures and short enough time (tens of years or less) that glass exchanges thoroughly but feldspar does not. The most likely process responsible for the O depletions at Chegem is a very high temperature (500-600??C), short-lived, vigorous meteoric-hydrothermal event that was focused within the upper 750 m of intracaldera tuff. Mass balance calculations indicate fluid fluxes of = 6 ?? 10-6 mol cm-2 s-1. We believe that the closest historical analogue to this Chegem hydrothermal event is the situation observed in the Valley of Ten Thousand Smokes (Alaska, USA), where hundreds of steam fumaroles with measured temperatures as high as 645??C persisted for 10 to 15 years in the much smaller welded ash-flow tuff sheet (??? 200 m thick) produced by the 1912 Katmai eruption.

Gazis, C.; Taylor, Jr. , H. P.; Hon, K.; Tsvetkov, A.

1996-01-01

236

Transfer time and source tracing in the soil - water- -plant system deciphered by the U-and Th-series short-lived nuclides  

NASA Astrophysics Data System (ADS)

Because soils form at the critical interface between the lithosphere and the atmosphere, characterization of the dynamics occurring through this compartment represents an important goal for several scientific fields and/or human activities. However, this issue remains a challenge because soils are complex systems, where a continuous evolution of minerals and organic soil constituents occurs in response to interactions with waters and vegetation. This study aims to investigate the relevance of short-lived nuclides of U- and Th-series to quantify the transfer times and scheme of radionuclides through a soil - water - plant ecosystem. Activities of (226Ra), (228Ra) and (228Th), as well as the long-lived (232Th), were measured by TIMS and gamma-spectrometry in the major compartments of a forested soil section, i.e.: solid soil fractions (exchangeable fraction, secondary phases and inherited primary minerals), waters (seepage soil waters and a spring further down the watershed) and vegetation (fine and coarse roots of beech trees, young and mature leaves). The matching of these nuclides half-live to bio-geochemical processes time-scale and the relatively good chemical analogy of radium with calcium make these isotopes especially suitable to investigate either time or mechanism of transfers within a soil-water-plant system. Indeed, the (228Ra/226Ra) isotopic ratios strongly differ in the range of samples, allowing quantifying the source and duration transfers. Analyses of the various solid soil fractions demonstrate a full redistribution of Ra isotopes between the inherited minerals and secondary soil phases. However, the transfer of these isotopes to the seepage water or to the tree roots does not follow a simple and obvious scheme. Both primary and secondary phases show to contribute to the dissolved radium. However, depending on the season, the tree leaves degradation also produces up to 70% of dissolved radium. Immobilization of a large part of this radium occurs within the first 70cm of the soil layer, either by plant uptake, or adsorption/ precipitation in particular soil layers. Consistently, the Ra isotope ratio in the spring water is similar to the inherited primary soil fraction, suggesting a "deep" (i.e. below the shallow 70cm of soil layer) origin of the exported dissolved radium and the short-scale effect of vegetation cycling onto radium transfer. The radium isotopic ratio in the trees roots does not match the soil exchangeable fraction, nor the seepage waters, but rather the bulk soil, suggesting a large and mixed pool of radium for roots uptake. Decay of 228Ra within the various parts of the trees allows calculating a vegetation cycling duration of about 10 years for this nuclide. Finally an unexpected large amount of unsupported 228Th in the tree leaves can only be explained by a preferential migration of the 228Ac (228Th precursor). The very short life of this nuclide allows therefore assessing that such transport from roots and deposition within stem and leaves take place within 30 hours at the most.

Rihs, S.; Pierret, M.; Chabaux, F.

2011-12-01

237

Light charged-particle production from proton- and {alpha}-induced reactions on natSi at energies from 25 to 65 MeV  

SciTech Connect

A series of in-beam experiments using proton and {alpha}-particle projectiles on natSi target has been performed at the Louvain-la-Neuve Cyclotron facility. Inclusive data of double-differential and differential cross sections, as well as total cross sections of all possible light charged particles emitted (p, d, t, 3He, {alpha}) were measured. The data are compared with the predictions of the nuclear-reaction code TALYS. A detailed discussion of the model calculations and the modifications required to improve the description of the data is presented.

Demetriou, P. [Institute of Nuclear Physics, NCSR 'Demokritos', 153.10 Athens (Greece); Institut de Physique Nucleaire, Universite catholique de Louvain, B-1348 Louvain-la-Neuve (Belgium); Dufauquez, Ch.; El Masri, Y. [Institut de Physique Nucleaire, Universite catholique de Louvain, B-1348 Louvain-la-Neuve (Belgium); Koning, A. J. [Nuclear Research and Consultancy Group NRG, P.O. 25, NL-1755 ZG Petten (Netherlands)

2006-04-26

238

Alpha Thalassemia  

MedlinePLUS

Alpha Thalassemia ? Physicians often mistake alpha thalassemia trait for iron deficiency anemia and incorrectly prescribe iron supplements that have no effect on the anemia. Normal alpha globin genes found on ...

239

{alpha} decay of the new isotope {sup 206}Ac  

SciTech Connect

The new neutron-deficient nuclide {sup 206}Ac was produced by bombarding a {sup 175}Lu target with 5.5 MeV/nucleon {sup 36}Ar ions. The evaporation residues were separated in flight by a gas-filled separator and subsequently identified by the {alpha}-{alpha} position and time correlation method. {sup 206}Ac was found to have two {alpha} particle emitting isomeric levels with half-lives of (22{sub {minus}5}{sup +9}) ms and (33{sub {minus}9}{sup +22}) ms, and with {alpha} particle energies of (7790{plus_minus}30) keV and (7750{plus_minus}20) keV, respectively. The former isomer is tentatively assigned to a J{sup {pi}}=3{sup +} level and the latter to a J{sup {pi}}=10{sup {minus}} level, both of which are also seen in the daughter and granddaughter nuclides {sup 202}Fr and {sup 198}At. Improved values of (27{sub {minus}6}{sup +11}) ms and (7693{plus_minus}25) keV for the half-life and {alpha} particle energy of {sup 207}Ac are also reported. {copyright} {ital 1998} {ital The American Physical Society}

Eskola, K. [Department of Physics, University of Helsinki, FIN-00014 Helsinki (Finland); Kuusiniemi, P.; Leino, M.; Cocks, J.F.; Enqvist, T.; Hurskanen, S.; Kettunen, H.; Trzaska, W.H.; Uusitalo, J. [Department of Physics, University of Jyvaeskylae, P.O. Box 35, FIN-40351 Jyvaeskylae (Finland); Allatt, R.G.; Greenlees, P.T.; Page, R.D. [Department of Physics, University of Liverpool, Liverpool L69 7ZE (United Kingdom)

1998-01-01

240

X. cap alpha. method as a tool for structure elucidation of short-lived transients generated by pulse radiolysis or flash photolysis. 1. Reductive reactions of PtCl\\/sup 2 -  

Microsoft Academic Search

Results serve to more clearly delineate the possible structures for platinum(III) chloro systems, and in particular they indicate that the trigonal-bipyramidal PtCl\\/sup 2 -\\/ is not to be favored. Furthermore, the comparison between theory and experiment points to the transient being distorted from strict O\\/sub h\\/ symmetry, in a manner generally consistent with an earlier proposal. For the forms with

A. Goursot; H. Chermette; E. Penigault; M. Chanon; W. L. Waltz

1984-01-01

241

On search and identification of short-lived super heavy cosmic-ray nuclei (Z >= 110) by fossil track study of the extraterrestrial crystals: Results and perspectives [II  

NASA Astrophysics Data System (ADS)

The existence of relatively stable super heavy elements (SHE) in Nature was predicted theoretically at the midst of the sixties (Nilsson, Nix, Sobichevsky, see Ref. [1]). Basing on nuclear shell model it was estimated, that double magic nuclei with atomic number 110 <= Z <= 114 and neutron number N = 184, namely, the double ``magic'' closed shells of nuclei can possess the life time at >=103 up to 109 years. Thus, these elements, similarly to Th and U, can survive in the Earth and meteorites since formation of Solar system ~ 4.6 billion years ago. The present project work was drastically stimulated by recent synthesis and discovery of very stable isotopes of SHE in Flerov Laboratory of Nuclear Reactions During 1999-2000 Oganessian and his colleagues succeed in obtaining of a number of rather neutron-rich isotopes of elements 112, 114 and 116 in the reactions of 48Ca with monoisotopic targets of 238U, 244Pu and 248Cm, respectively [2]. The most stable isotope obtained is odd-even nuclear 285112, which possess the life time in between 10-30 min. Still this isotope has only 173 neutrons which is 11 fewer as compared with the magic number N = 184. For the region of known actinide nuclei (Z = 89 - 98) such a neutron difference for the most stable isotopes provides the stabilization factor of 1010 - 1013 in the life time. The discovery of very stable isotope of the new element 112 provides firstly the final unambiguous proof on the existence of new island of very stable SHE nuclei. Now we pointed out that there is no way to get the neutron number N = 184 using present accelerators and target nuclei. The only one way to find out double magic SHE nuclei now is the search for these nuclei in natural samples. The experimental attempts to discover such long-lived SHE nuclei with the life time >=2108 y in natural samples undertaken during the late sixties up to end of seventies provided some evidence of their existence in a number of both terrestrial samples and meteorites. These experiments were done by the investigation of alpha radioactivity and spontaneous fission activity, which exceeds significantly the effect due to the spontaneous fission of 238U nuclide. Still no decisive information on the existence of SHE in the nature was obtained.

Perelygin, V. P.; Abdullaev, I. G.; Bondar, Yu. V.; Brandt, R.; Chuburkov, Yu. T.; Kashkarov, L. L.; Knyazeva, G. P.; Kravets, L. I.; Spohr, R.; Stetsenko, S. G.; Vater, P.

2003-05-01

242

Direct Mass Measurements of Short-Lived A=2Z-1 Nuclides {sup 63}Ge, {sup 65}As, {sup 67}Se, and {sup 71}Kr and Their Impact on Nucleosynthesis in the rp Process  

SciTech Connect

Mass excesses of short-lived A=2Z-1 nuclei {sup 63}Ge, {sup 65}As, {sup 67}Se, and {sup 71}Kr have been directly measured to be -46 921(37), -46 937(85), -46 580(67), and -46 320(141) keV, respectively. The deduced proton separation energy of -90(85) keV for {sup 65}As shows that this nucleus is only slightly proton unbound. X-ray burst model calculations with the new mass excess of {sup 65}As suggest that the majority of the reaction flow passes through {sup 64}Ge via proton capture, indicating that {sup 64}Ge is not a significant rp-process waiting point.

Tu, X. L.; Du, C. M.; Geng, P.; Jin, S. L.; Liu, L. X.; Tang, S. W.; Wang, S. T.; Xu, X.; Yan, X. L.; Ye, R. P.; Zang, Y. D. [Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000 (China)] [Graduate University of Chinese Academy of Sciences, Beijing, 100049 (China); Xu, H. S.; Wang, M.; Zhang, Y. H.; Zhou, X. H.; Yuan, Y. J.; Xia, J. W.; Hu, Z. G.; Huang, W. X.; Liu, Y. [Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000 (China)

2011-03-18

243

Correlation measurements of light charged particles emitted at 20{degrees} from 140 MeV {sup 16}O+{sup 27}Al and {sup 18}O + {sub 27}Al reactions  

SciTech Connect

We have measured small angle correlations between light particles (p,d,t,{alpha}) at an energy of 140 for the {sup 16}O+{sup 27}Al and {sup 18}O+{sup 27}Al systems. The correlation functions were measured at a laboratory angle of 20{degrees} with the Stony Brook LINAC. As for earlier work, the p-p and p-d results from both systems are well fit by a model which assumes statistical emission from an equilibrated compound nucleus. The d-{alpha} and {alpha}-{alpha} results from the two systems can be reproduced if a small amount of decaying excited {sup 6}Li or {sup 8}Be are included in the simulation. Finally, the relative two particle yields and deduced {sup 8}Be yield, which are very different for the two systems, will be compared to predictions based on statistical emission.

Deyoung, P.A.; Gelerloos, C.J.; Sarafa, J. [and others

1993-10-01

244

Pre-Equilibrium Alpha-Particle Emission as a Probe to Explore Alpha Clustering in Nuclei  

NASA Astrophysics Data System (ADS)

Experimental data of the double-differential spectra of light particles emitted at pre-equilibrium stage of nuclear processes were obtained at Laboratori Nazionali di Legnaro for the heavy-ion reactions 130 and 250 MeV 16O + 116Sn. Light charged particles were measured in coincidence with evaporation residues in order to avoid unwanted competing mechanisms. The experimental data were collected in a wide angular range from 29 to 82 degrees in the laboratory system. Theoretical model was developed in order to describe simultaneously evaporative and pre-equilibrium emission of the light particles in heavy-ion reactions. Griffin exciton model was used for the description of the pre-equilibrium stage of the compound nucleus formation, while the equilibrium evaporation processes were analyzed in the framework of the statistical theory of heavy-ion reactions. Experimental data were compared with the results of the model calculations and new approach was suggested to take into account alpha cluster formation in the projectile nucleus by measuring and analyzing pre-equilibrium alpha-particle spectra.

Kravchuk, V. L.; Fotina, O. V.; Gramegna, F.; Bruno, M.; D'Agostino, M.; Sambi, S.; Barlini, S.; Casini, G.

245

Advanced alpha spectrum analysis based on the fitting and covariance analysis of dependent variables  

NASA Astrophysics Data System (ADS)

The correct handling of statistical uncertainties is crucial especially when unfolding alpha spectra that contain a low number of counts or overlapping peaks from different nuclides. For this purpose, we have developed a new spectrum analysis software package called ADAM, which performs a full covariance calculus for alpha-particle emitting radionuclides. By analyzing a large number of simulated and measured spectra, the program was proved to give unbiased peak areas and statistically correct uncertainty limits. This applies regardless of the peak areas and the number of unknown parameters during the fitting. In addition, ADAM performs reliable deconvolution for multiplets, which opens the way for the determination of isotope ratios, such as 239Pu/240Pu.

Ihantola, S.; Pelikan, A.; Pllnen, R.; Toivonen, H.

2011-11-01

246

Targeted alpha-particle radiotherapy with 211At-labeled monoclonal antibodies.  

PubMed

An attractive feature of targeted radionuclide therapy is the ability to select radionuclides and targeting vehicles with characteristics that are best suited for a particular clinical application. One combination that has been receiving increasing attention is the use of monoclonal antibodies (mAbs) specifically reactive to receptors and antigens that are expressed in tumor cells to selectively deliver the alpha-particle-emitting radiohalogen astatine-211 (211At) to malignant cell populations. Promising results have been obtained in preclinical models with multiple 211At-labeled mAbs; however, translation of the concept to the clinic has been slow. Impediments to this process include limited radionuclide availability, the need for suitable radiochemistry methods operant at high activity levels and lack of data concerning the toxicity of alpha-particle emitters in humans. Nonetheless, two clinical trials have been initiated to date with 211At-labeled mAbs, and others are planned for the near future. PMID:17921029

Zalutsky, Michael R; Reardon, David A; Pozzi, Oscar R; Vaidyanathan, Ganesan; Bigner, Darell D

2007-05-11

247

Alpha-particle-induced cancer in humans.  

PubMed

Updated information is given on alpha-particle-induced cancer in persons internally exposed to 222Rn progeny, Thorotrast, long-lived 226Ra and 228Ra, and short-lived 224Ra. The lung cancer risk to persons breathing 222Rn progeny in the indoor air of offices, schools, and homes is of increasing concern. About half of the recent deaths among the German Thorotrast patients have been from liver cancer. Animal studies indicate that the liver cancer risk from Thorotrast is mainly from its radioactivity and that the risk coefficient for the Thorotrast patients can be used provisionally for other alpha emitters in the human liver. Six skeletal cancers have occurred in persons with average skeletal doses between 0.85 and 11.8 Gy from 226Ra and 228Ra. In the low-dose German 224Ra patients, two skeletal sarcomas have occurred at about 0.7 Gy compared to about six cases predicted by results from 224Ra patients at higher doses. The minimal appearance time for radiation-induced bone sarcomas in humans is about 4 y. Following brief irradiation, the vast majority of induced bone sarcomas are expressed by about 30 y. Recent evidence against the "practical threshold" hypothesis is given. With the downward revision of neutron doses to the atomic-bomb survivors, the follow-up of persons exposed to alpha particles may be the best opportunity to evaluate directly the effects of high LET radiation on humans. PMID:2844697

Mays, C W

1988-10-01

248

Cross section measurements for neutron-induced reactions off C, Al, SiO2, Si and Au producing relatively short-lived radionuclides at neutron energies between 70 and 160 MeV  

NASA Astrophysics Data System (ADS)

A systematic study was made to measure many cross sections for relevant neutron-induced reactions. This study was motivated by the need to better understand cosmic ray interactions with extraterrestrial materials. The major constituents of meteorites and lunar rocks include oxygen, silicon, and aluminum. The primary aim was to measure cross sections for neutron-induced reactions producing long-lived radionuclides (e.g. 14C) and stable isotopes (e.g. Ne isotopes) but the irradiation conditions allowed cross sections for many reactions producing relatively short-lived radionuclides (e.g. 22Na) to be well measured. Monitor foils used in the irradiations included C, Al, and Au. Quasi-monoenergetic neutron beams were produced by bombarding Be targets with 80, 120 and 160 MeV proton beams at iThemba LABS, South Africa. Two identical target stacks were irradiated in beam lines at 0 and 16 to the incident proton beam direction. The yield at an unique neutron energy was obtained by subtracting the yield measured at 16 (after suitable normalization) from that measured at 0. The cross sections for the following reactions: 27Al(n,x)22,24Na; natC(n,x)7Be; 197Au(n,x)194,196Au; SiO2(n,x)22Na and natSi(n,x)24Na are reported.

Sisterson, Janet M.

2007-08-01

249

DIFFERENCES AND SIMILARITIES IN ANDRA'S ASSESSMENT OF ACTIVITIES CARRIED OUT BY RADIOACTIVE WASTE GENERATORS AND AFFECTING THE QUALITY OF IL-LL SHORT-LIVED WASTE PACKAGES AND HL-IL LONG-LIVED WASTE PACKAGES  

SciTech Connect

In both cases of packages for either low-level and intermediate-level short-lived (LL-IL/SL) or high-level and intermediate-level long-lived (HL-IL/LL) radioactive waste, Andra has defined a quality reference system, manages it, follows up its appropriate implementation in production plants and verifies its effectiveness in production. The purpose of such a reference system is to ensure, in the first case, that waste packages comply with the Centre de l'Aube's acceptance criteria and, in the second case, that the characteristics submitted by the waste generators to Andra as input data for the deep geological repository project reflect the actual production conditions. In that context, the three management steps of the quality reference system include differences due to the fact that HL-IL/SL packages have not been submitted yet to any technical acceptance criterion. Compliance with any such criterion should be the subject of a characterization report during the qualification phase and of a examination during the verification phase. The management of the quality reference system also involves similarities that facilitate the joint work carried out by Andra with the waste generators, especially in the facilities where both package types are produced.

Trentesaux, C.; Cairon, P.; Dumont, J.-N.; Felix, B.; Losada, F.

2003-02-27

250

Alpha detection in pipes using an inverting membrane scintillator  

SciTech Connect

Characterization of surface alpha emitting contamination inside enclosed spaces such as piping systems presents an interesting radiological measurement challenge. Detection of these alpha particles from the exterior of the pipe is impossible since the alpha particles are completely absorbed by the pipe wall. Traditional survey techniques, using hand-held instruments, simply can not be used effectively inside pipes. Science and Engineering Associates, Inc. is currently developing an enhancement to its Pipe Explorer{trademark} system that will address this challenge. The Pipe Explorer{trademark} uses a unique sensor deployment method where an inverted tubular membrane is propagated through complex pipe runs via air pressure. The inversion process causes the membrane to fold out against the pipe wall, such that no part of the membrane drags along the pipe wall. This deployment methodology has been successfully demonstrated at several DOE sites to transport specially designed beta and gamma scintillation detectors into pipes ranging in length up to 250 ft. The measurement methodology under development overcomes the limitations associated with conventional hand-held survey instruments by remotely emplacing an alpha scintillator in direct contact with the interior pipe surface over the entire length to be characterized. This is accomplished by incorporating a suitable scintillator into the otherwise clear membrane material. Alpha particles emitted from the interior pipe surface will intersect the membrane, resulting in the emission of light pulses from the scintillator. A photodetector, towed by the inverting membrane, is used to count these light pulses as a function of distance into the pipe, thereby producing a log of the surface alpha contamination levels. It is anticipated that the resulting system will be able to perform measurements in pipes as small as two inches in diameter, and several hundred feet in length.

Kendrick, D.T.; Cremer, C.D.; Lowry, W.; Cramer, E.

1995-12-31

251

EVOLUTION OF THE SOLAR NEBULA. IX. GRADIENTS IN THE SPATIAL HETEROGENEITY OF THE SHORT-LIVED RADIOISOTOPES {sup 60}Fe AND {sup 26}Al AND THE STABLE OXYGEN ISOTOPES  

SciTech Connect

Short-lived radioisotopes (SLRIs) such as {sup 60}Fe and {sup 26}Al were likely injected into the solar nebula in a spatially and temporally heterogeneous manner. Marginally gravitationally unstable (MGU) disks, of the type required to form gas giant planets, are capable of rapid homogenization of isotopic heterogeneity as well as of rapid radial transport of dust grains and gases throughout a protoplanetary disk. Two different types of new models of an MGU disk in orbit around a solar-mass protostar are presented. The first set has variations in the number of terms in the spherical harmonic solution for the gravitational potential, effectively studying the effect of varying the spatial resolution of the gravitational torques responsible for MGU disk evolution. The second set explores the effects of varying the initial minimum value of the Toomre Q stability parameter, from values of 1.4 to 2.5, i.e., toward increasingly less unstable disks. The new models show that the basic results are largely independent of both sets of variations. MGU disk models robustly result in rapid mixing of initially highly heterogeneous distributions of SLRIs to levels of {approx}10% in both the inner (<5 AU) and outer (>10 AU) disk regions, and to even lower levels ({approx}2%) in intermediate regions, where gravitational torques are most effective at mixing. These gradients should have cosmochemical implications for the distribution of SLRIs and stable oxygen isotopes contained in planetesimals (e.g., comets) formed in the giant planet region ({approx}5 to {approx}10 AU) compared to those formed elsewhere.

Boss, Alan P., E-mail: boss@dtm.ciw.edu [Department of Terrestrial Magnetism, Carnegie Institution of Washington, 5241 Broad Branch Road, NW, Washington, DC 20015-1305 (United States)

2011-10-01

252

Sterically stabilized liposomes as a carrier for alpha-emitting radium and actinium radionuclides.  

PubMed

The alpha-particle emitting radionuclides (223)Ra (t(1/2) = 11.4 d), (224)Ra (t(1/2) = 3.6 d), and (225)Ac(t(1/2) = 10.0 d) may have a broad application in targeted radiotherapy provided that they could be linked to vehicles with tumor affinity. The potential usefulness of liposomes as carriers was studied in the present work. Radium and actinium radionuclides could be loaded in good yields into sterically stabilized liposomes. Subsequent coating of the liposomes with a folate-F(ab')(2) construct yielded a product with affinity towards tumor cells expressing folate receptors. Radionuclide loaded liposomes showed excellent stability in serum in vitro. PMID:15093814

Henriksen, Gjermund; Schoultz, B W; Michaelsen, T E; Bruland, S; Larsen, R H

2004-05-01

253

RAPID DETERMINATION OF ACTINIDES IN URINE BY INDUCTIVELY-COUPLED PLASMA MASS SPECTROMETRY AND ALPHA SPECTROMETRY: A HYBRID APPROACH  

SciTech Connect

A new rapid separation method that allows separation and preconcentration of actinides in urine samples was developed for the measurement of longer lived actinides by inductively coupled plasma mass spectrometry (ICP-MS) and short-lived actinides by alpha spectrometry; a hybrid approach. This method uses stacked extraction chromatography cartridges and vacuum box technology to facilitate rapid separations. Preconcentration, if required, is performed using a streamlined calcium phosphate precipitation. Similar technology has been applied to separate actinides prior to measurement by alpha spectrometry, but this new method has been developed with elution reagents now compatible with ICP-MS as well. Purified solutions are split between ICP-MS and alpha spectrometry so that long- and short-lived actinide isotopes can be measured successfully. The method allows for simultaneous extraction of 24 samples (including QC samples) in less than 3 h. Simultaneous sample preparation can offer significant time savings over sequential sample preparation. For example, sequential sample preparation of 24 samples taking just 15 min each requires 6 h to complete. The simplicity and speed of this new method makes it attractive for radiological emergency response. If preconcentration is applied, the method is applicable to larger sample aliquots for occupational exposures as well. The chemical recoveries are typically greater than 90%, in contrast to other reported methods using flow injection separation techniques for urine samples where plutonium yields were 70-80%. This method allows measurement of both long-lived and short-lived actinide isotopes. 239Pu, 242Pu, 237Np, 243Am, 234U, 235U and 238U were measured by ICP-MS, while 236Pu, 238Pu, 239Pu, 241Am, 243Am and 244Cm were measured by alpha spectrometry. The method can also be adapted so that the separation of uranium isotopes for assay is not required, if uranium assay by direct dilution of the urine sample is preferred instead. Multiple vacuum box locations may be set-up to supply several ICP-MS units with purified sample fractions such that a high sample throughput may be achieved, while still allowing for rapid measurement of short-lived actinides by alpha spectrometry.

Maxwell, S.; Jones, V.

2009-05-27

254

Rapid determination of actinides in urine by inductively coupled plasma mass spectrometry and alpha spectrometry: a hybrid approach.  

PubMed

A new rapid separation method that allows separation and preconcentration of actinides in urine samples was developed for the measurement of longer lived actinides by inductively coupled plasma mass spectrometry (ICP-MS) and short-lived actinides by alpha spectrometry; a hybrid approach. This method uses stacked extraction chromatography cartridges and vacuum box technology to facilitate rapid separations. Preconcentration, if required, is performed using a streamlined calcium phosphate precipitation. Similar technology has been applied to separate actinides prior to measurement by alpha spectrometry, but this new method has been developed with elution reagents now compatible with ICP-MS as well. Purified solutions are split between ICP-MS and alpha spectrometry so that long- and short-lived actinide isotopes can be measured successfully. The method allows for simultaneous extraction of 24 samples (including QC samples) in less than 3h. Simultaneous sample preparation can offer significant time savings over sequential sample preparation. For example, sequential sample preparation of 24 samples taking just 15 min each requires 6h to complete. The simplicity and speed of this new method makes it attractive for radiological emergency response. If preconcentration is applied, the method is applicable to larger sample aliquots for occupational exposures as well. The chemical recoveries are typically greater than 90%, in contrast to other reported methods using flow injection separation techniques for urine samples where plutonium yields were 70-80%. This method allows measurement of both long-lived and short-lived actinide isotopes. (239)Pu, (242)Pu, (237)Np, (243)Am, (234)U, (235)U and (238)U were measured by ICP-MS, while (236)Pu, (238)Pu, (239)Pu, (241)Am, (243)Am and (244)Cm were measured by alpha spectrometry. The method can also be adapted so that the separation of uranium isotopes for assay is not required, if uranium assay by direct dilution of the urine sample is preferred instead. Multiple vacuum box locations may be set-up to supply several ICP-MS units with purified sample fractions such that a high sample throughput may be achieved, while still allowing for rapid measurement of short-lived actinides by alpha spectrometry. PMID:19782204

Maxwell, Sherrod L; Jones, Vernon D

2009-06-24

255

Phase I Rinal Report: Ultra-Low Background Alpha Activity Counter  

SciTech Connect

In certain important physics experiments that search for rare-events, such as neutrino or double beta decay detections, it is critical to minimize the number of background events that arise from alpha particle emitted by the natural radioactivity in the materials used to construct the experiment. Similarly, the natural radioactivity in materials used to connect and package silicon microcircuits must also be minimized in order to eliminate ''soft errors'' caused by alpha particles depositing charges within the microcircuits and thereby changing their logic states. For these, and related reasons in the areas of environmental cleanup and nuclear materials tracking, there is a need that is important from commercial, scientific, and national security perspectives to develop an ultra-low background alpha counter that would be capable of measuring materials' alpha particle emissivity at rates well below 0.00001 alpha/cm{sup 2}/hour. This rate, which corresponds to 24 alpha particles per square meter per day, is essentially impossible to achieve with existing commercial instruments because the natural radioactivity of the materials used to construct even the best of these counters produces background rates at the 0.005 alpha/cm{sup 2}/hr level. Our company (XIA) had previously developed an instrument that uses electronic background suppression to operate at the 0.0005 0.005 alpha/cm{sup 2}/hr level. This patented technology sets up an electric field between a large planar sample and a large planar anode, and fills the gap with pure Nitrogen. An alpha particle entering the chamber ionizes the Nitrogen, producing a ''track'' of electrons, which drift to the anode in the electric field. Tracks close to the anode take less than 10 microseconds (us) to be collected, giving a preamplifier signal with a 10 us risetime. Tracks from the sample have to drift across the full anode-sample gap and produce a 35 us risetime signal. By analyzing the preamplifier signals with a digital signal processor we easily distinguish between these two risetimes and thereby count only alpha particles emitted by the sample. Alpha particles emitted from the sample tray are absorbed in the rear of the sample, so the tray's emissivity does not contribute to the background either. Extensions of the method to the counter's sidewalls similarly allow us to reject alpha particles emitted from the sidewalls. We can thus able obtain background rates over a factor of 1000 lower than in conventional instruments without active background rejection. Extending this principle to count at the 0.00001 alpha/cm{sup 2}/hour, level encounters difficulties because there will typically be only 2.4 alpha particles per square meter per day. Since about 6 counts are required to measure activity at the 95% confidence level, large sample areas are required to make measurements in reasonable times. Unfortunately, increasing the counter's anode area to a square meter raises its capacitance so much that the preamplifier noise levels swamp the alpha particle signals and make counting impossible. In this SBIR we worked to solve this dilemma by segmenting the single large area electrode into several smaller, lower capacitance electrodes that could still detect the alpha particles reliably. Each electrode would have its own electronic and we would capture signals from all of them in coincidence (since an alpha track might well deposit charge on more than one electrode), a technique in which XIA is experienced. Therefore, in Phase I we worked to show proof of principle by subdividing our original 1,800 cm{sup 2} electrode into 4 square segments, each 625 cm{sup 2} and demonstrating that signal noise on individual channels reduced as expected. Because the Phase II counter with a 1 m{sup 2} segmented anode would require 16 segments plus a segmented guard as well, we also designed low cost signal processing electronics to instrument it in Phase II. Our Phase I effort met our major proof of principle goals. In particular, reducing the anode size by a factor of 4 in area reduced electronic noise b

Warburton, W.K.

2005-07-22

256

Metastable ion study of fluorinated organic compounds. Part 3. [alpha], [alpha], [alpha]-trifluoroanisole and [alpha], [alpha], [alpha]-trifluorocresols  

Microsoft Academic Search

The spontaneous unimolecular dissociation reactions of the molecular ions of the C7H5F3O positional isomers [alpha], [alpha], [alpha]-trifluoroanisole (1), o-[alpha], [alpha], [alpha],-trifluorocresol (2) and m-[alpha], [alpha], [alpha]-trilfluorocresol (3), have been investigated by mass-analyzed ion kinetic energy (MIKE) spectrometry and deuterium-labellin. The results are compared with those of the non-fluorinated analogues anisole (4), o-cresol (5) and m-cresol (6). Ions 1.+ and 4.+

Tamae Yanagisawa; Susumu Tajima; Masaki Iizuka; Seiji Tobita; Motohiro Mitani; Takeo Matsumoto

1993-01-01

257

Relative biological effectiveness of alpha-particle emitters in vivo at low doses  

SciTech Connect

The therapeutic potential of radionuclides that emit [alpha] particles, as well as their associated health hazards, have attracted considerable attention. The [sup 224]Ra daughters [sup 212]Pb and [sup 212]Bi, by virtue of their radiation properties which involve emission of [alpha] and [beta] particles in their decay to stable [sup 208]Pb, have been proposed as candidates for radioimmunotherapy. Using mouse testes as the experimental model and testicular spermhead survival as the biological end point, the present work examines the radiotoxicity of [sup 212]Pb and its daughters. When [sup 212]Pb, in equilibrium with its daughters [sup 212]Bi, [sup 212]Po and [sup 208]Tl, was administered directly into the testis, the dose required to achieve 37% survival (D[sub 37]) was 0.143 [+-] 0.014 Gy and the corresponding RBE of the mixed radiation field was 4.7 when compared to the D[sub 37] for acute external 120 kVp X rays. This datum, in conjunction with our earlier results for [sup 210]Po, was used to obtain an RBE-LET relationship for [alpha] particles emitted by tissue-incorporated radionuclides: RBE[sub [alpha

Howell, R.W.; Azure, M.T.; Narra, V.R.; Rao, D.V. (Univ. of Medicine and Dentistry of New Jersey, Newark, NJ (United States))

1994-03-01

258

Alpha Backgrounds for HPGe Detectors in Neutrinoless Double-Beta Decay Experiments  

SciTech Connect

The Majorana Experiment will use arrays of enriched HPGe detectors to search for the neutrinoless double-beta decay of 76Ge. Such a decay, if found, would show lepton-number violation and confirm the Majorana nature of the neutrino. Searches for such rare events are hindered by obscuring backgrounds which must be understood and mitigated as much as possible. A potentially important background contribution to this and other double-beta decay experiments could come from decays of alpha-emitting isotopes in the 232Th and 238U decay chains on or near the surfaces of the detectors. An alpha particle emitted external to an HPGe crystal can lose energy before entering the active region of the detector, either in some external-bulk material or within the dead region of the crystal. The measured energy of the event will only correspond to a partial amount of the total kinetic energy of the alpha and might obscure the signal from neutrinoless double-beta decay. A test stand was built and measurements were performed to quantitatively assess this background. We present results from these measurements and compare them to simulations using Geant4. These results are then used to measure the alpha backgrounds in an underground detector in situ. We also make estimates of surface contamination tolerances for double-beta decay experiments using solid-state detectors.

Johnson, R. A. [University of Washington, Seattle; Burritt, T. H. [University of Washington, Seattle; Elliott, S. R. [Los Alamos National Laboratory (LANL); Gehman, V. M. [Los Alamos National Laboratory (LANL); Guiseppe, V.E. [University of South Dakota; Wilkerson, J. F. [UNC/Triangle Univ. Nucl. Lab, Durham, NC/ORNL

2012-01-01

259

Efficacy of astatine-211-labeled monoclonal antibody in treatment of murine T-cell lymphoma  

Microsoft Academic Search

The short-lived isotope ²¹¹At (half-life, 7.2 hr), an alpha particle-emitting halogen, has been attached to a monoclonal antibody (anti-thy 1.1, IgG1, OX7) and used in mice in the treatment of a thy 1.1 T-cell lymphoma (A120). Forty-eight hours after receiving an iv injection of 10(3) or 10(5) A120 cells, mice were treated with phosphate-buffered saline, ²¹¹At-, antibody alone, or ²¹¹At

A. Harrison; L. Royle

1987-01-01

260

Simultaneous determination of gross alpha, gross beta and (226)Ra in natural water by liquid scintillation counting.  

PubMed

The determination of gross alpha, gross beta and (226)Ra activity in natural waters is useful in a wide range of environmental studies. Furthermore, gross alpha and gross beta parameters are included in international legislation on the quality of drinking water [Council Directive 98/83/EC].(1) In this work, a low-background liquid scintillation counter (Wallac, Quantulus 1220) was used to simultaneously determine gross alpha, gross beta and (226)Ra activity in natural water samples. Sample preparation involved evaporation to remove (222)Rn and its short-lived decay daughters. The evaporation process concentrated the sample ten-fold. Afterwards, a sample aliquot of 8mL was mixed with 12mL of Ultima Gold AB scintillation cocktail in low-diffusion vials. In this study, a theoretical mathematical model based on secular equilibrium conditions between (226)Ra and its short-lived decay daughters is presented. The proposed model makes it possible to determine (226)Ra activity from two measurements. These measurements also allow determining gross alpha and gross beta simultaneously. To validate the proposed model, spiked samples with different activity levels for each parameter were analysed. Additionally, to evaluate the model's applicability in natural water, eight natural water samples from different parts of Spain were analysed. The eight natural water samples were also characterised by alpha spectrometry for the naturally occurring isotopes of uranium ((234)U, (235)U and (238)U), radium ((224)Ra and (226)Ra), (210)Po and (232)Th. The results for gross alpha and (226)Ra activity were compared with alpha spectrometry characterization, and an acceptable concordance was obtained. PMID:23415246

Fons, J; Zapata-Garca, D; Tent, J; Llaurad, M

2013-02-13

261

Cancer Stem Cell Targeting Using the Alpha-Particle Emitter, 213Bi: Mathematical Modeling and Feasibility Analysis  

PubMed Central

There is increasing recognition that treatment failure in cancer may be associated with the failure to sterilize a small subpopulation of tumor cells that have been characterized as tumor stem cells. Defined as cells that are able to self-renew and also to replenish a phenotypically diverse tumor-cell population, such cells are also considered resistant to chemotherapy. These characteristics are optimal for targeting by using alpha-particle-emitting radionuclides. Because of their high-energy deposition density per track, alpha-particles are capable of targeting single cells or small clusters of cells with minimal normal organ toxicity. The DNA damage induced by alpha-particles is largely irreparable and, therefore, alpha-particle-induced damage is minimally susceptible to resistance mechanisms. In this work, theoretical modeling was performed to examine the potential of alpha-emitter targeting of such small clusters of cancer stem cells. Critical parameters influencing efficacy and toxicity were identified and their relationship elucidated. The results identify specific activity, antigen site density, and number of target cells as critical parameters for effective cell killing and demonstrate substantial efficacy gains by targeting a smaller number of stem cells, as opposed to the entire tumor-cell population.

Sgouros, George; Song, Hong

2010-01-01

262

Tamsulosin, a selective alpha 1-adrenoceptor antagonist, inhibits fertility of male rats.  

PubMed

This study examined the antifertility effects of tamsulosin, a highly potent and a selective, alpha 1-adrenoceptor antagonist, on male rats. The drug was administered subcutaneously as a single dose (0.15 mg kg-1). The drug caused a significant reduction in fertility (measured by number of uterine implants, quantal pregnancy, and fertility index). The antifertility effect was short lived and rapid in both onset (no later than 7 h of administration) and recovery (within 7 d). Libido and mating performance remained essentially uninhibited. On the other hand, the antifertility effect was accompanied by significant impairment in ejaculatory competence and enhancement of pre-implantation losses. Based on the results of this study and our previous studies it is concluded that alpha 1-adrenoceptor blockade has a potent antifertility effect in male rats. PMID:7913799

Ratnasooriya, W D; Wadsworth, R M

263

ELEMENTAL COMPOSITION OF SIZED PARTICLES EMITTED FROM STATIONARY SOURCES  

EPA Science Inventory

This paper discusses several approaches for obtaining the elemental and, in a few cases, inorganic compound identification in sized particles. The elemental analyses are done by wavelength dispersion x-ray fluorescence (WXRF). Fourier Transform infrared is being used for inorgani...

264

Prolonging the half-life of human interferon-alpha 2 in circulation: Design, preparation, and analysis of (2-sulfo-9-fluorenylmethoxycarbonyl)7- interferon-alpha 2.  

PubMed

Polypeptide drugs are generally short-lived species in circulation. In this study, we have covalently linked seven moieties of 2-sulfo-9-fluorenylmethoxycarbonyl (FMS) to the amino groups of human interferon-alpha2. The derivative thus obtained (FMS(7)-IFN-alpha2) has approximately 4% the biological potency and 33 +/- 4% the receptor binding capacity of the native cytokine. Upon incubation, FMS(7)-IFN-alpha2 undergoes time-dependent spontaneous hydrolysis, generating active interferon with t(1/2) values of 24 +/- 2 h at pH 8.5 and 98 +/- 10 h at pH 7.4. When native IFN-alpha2 is intravenously administered to mice, circulating antiviral activity is maintained for a short duration and then declines with t(1/2) = 4 +/- 0.5 h, reaching undetectable values at approximately 18 h after administration. With intravenously administered FMS(7)-IFN-alpha2, there is a lag period of 2 h, followed by a progressive elevation in circulating antiviral-active protein, which peaked at 20 h and declined with t(1/2) = 35 +/- 4 h. FMS(7)-IFN-alpha2 is resistant to alpha-chymotrypsin digest and to proteolytic inactivation by human serum proteases in vitro. We have thus introduced here an inactive IFN-alpha2 derivative, which is resistant to in situ inactivation and has the capability of slowly reverting to the native active protein at physiological conditions in vivo and in vitro. Having these attributes, FMS(7)-IFN-alpha2 maintains prolonged circulating antiviral activity in mice, exceeding 7-8 times the activity of intravenously administered native cytokine. PMID:11158619

Shechter, Y; Preciado-Patt, L; Schreiber, G; Fridkin, M

2001-01-30

265

The feasibility of 225Ac as a source of alpha-particles in radioimmunotherapy.  

PubMed

This paper proposes the utilization of 225Ac for the alpha-radioimmunotherapy of cancer. The isotope decays with a radioactive half-life of 10 days into a cascade of short-lived alpha- and beta-emitting isotopes. In addition, when indicated by the pharmacokinetic requirements of particular clinical applications, 213Bi, with a radioactive half-life of 47 min, can be chosen as an alternative source of alpha-particles in radioimmunotherapy. This isotope is the last alpha emitter in the 225Ac decay-cascade and can be extracted from a 225Ac source at the bedside of the patient. 225Ac can quasi ad infinitum be obtained from one of its precursors, 229Th, which can be made available by various means. The indications for the use of alpha-particles as an alternative to more traditional classes of radiation are derived from the particle-kinetic characteristics and the radioactive half-life of their source isotope, as well as from the properties of the target-selective carrier moiety for the source isotope. It may be expected that useful applications, complementary to and/or in conjunction with other means of therapy will be identified. PMID:8429990

Geerlings, M W; Kaspersen, F M; Apostolidis, C; van der Hout, R

1993-02-01

266

Radon progeny as sources of gross-alpha radioactivity anomalies in ground water  

SciTech Connect

Gross-alpha radiation data from ground water samples are subject to variability introduced as a result of analytical procedure. For example, ground water in the surficial aquifer of central Florida commonly has gross-alpha radioactivity in excess of 555 Bq m-3 (15 pCi L-1). This activity, commonly unsupported by Ra, often results from the SSSRn progeny. The relatively short-lived daughters of SSSRn can give rise to variations in gross-alpha measurements of up to 2 orders of magnitude in replicate samples. Polonium-210, a longer-lived Rn daughter, is also found in concentrations greater than predicted by the Ra content. As a consequence, it is suggested that gross-alpha measurements include Po analyses with Ra and U when standards are exceeded. It should be recognized that, depending on the activity of S Pb, S Po activity may vary significantly with holding time. Variations of measured Po activity in replicate samples collected and prepared by present methods indicate that Po analyses may be inconsistent and frequently underestimate total Po activity. Sample preparation methods and measurement techniques are discussed which greatly improve the overall accuracy and consistency of gross-alpha and Po analyses.

Oural, C.R.; Upchurch, S.B.; Brooker, H.R.

1988-12-01

267

mFISH analysis reveals complexity of chromosome aberrations in individuals occupationally exposed to internal plutonium: a pilot study to assess the relevance of complex aberrations as biomarkers of exposure to high-LET alpha particles.  

PubMed

We recently demonstrated that a significant proportion of apparently stable insertions induced after exposure to a mean of one alpha particle/cell, detected using three-color FISH, were part of larger unstable complexes when visualized by 24-color FISH. Interestingly, regardless of the long-term persistence capability of the cell, the complexity of each alpha-particle-induced complex appeared to be specific to the nuclear traversal of a single alpha particle. To assess whether aberrations of a similar complexity are observed in vivo and also to examine the usefulness of detecting such aberrations as a biomarker of chronic exposure to alpha particles, we have carried out a limited pilot study of Russian workers with large body burdens of alpha-particle-emitting plutonium. We found unstable cells containing non-transmissible complex aberrations in all of the plutonium-exposed subjects analyzed by mFISH. In addition, all of the complexes seen were consistent with those previously observed in vitro. Non-transmissible complex aberrations were more common than transmissible-type complexes, consistent with ongoing/chronic exposure, and insertions were dominant features of both types of complex. Accordingly, this preliminary study supports the proposal that aberration complexity and non-transmissibility are the major cytogenetic features of alpha-particle exposure that could potentially be exploited as a specific indicator of chronic exposures to high-LET alpha particles. PMID:15606304

Anderson, Rhona M; Tsepenko, Viktoria V; Gasteva, Galina N; Molokanov, Alexander A; Sevan'kaev, Aleksander V; Goodhead, Dudley T

2005-01-01

268

Measurement of the {sup 40}Ca({alpha},{gamma}){sup 44}Ti reaction relevant for supernova nucleosynthesis  

SciTech Connect

The short-lived nuclide {sup 44}Ti is an important nuclide for the understanding of explosive nucleosynthesis. The main production reaction, {sup 40}Ca({alpha},{gamma}){sup 44}Ti, has been studied in inverse kinematics with the recoil mass spectrometer DRAGON located at the TRIUMF-ISAC facility in Vancouver, Canada. The temperature range relevant for {alpha}-rich freeze-out during a core-collapse supernova has been covered entirely with a {sup 40}Ca beam of 0.60 to 1.15 MeV/nucleon. All relevant quantities for the calculation of the astrophysical reaction rate have been measured directly. Because of many previously undiscovered resonances, the reaction rate derived from the energy dependent {sup 44}Ti yield is higher than the one based on previous prompt {gamma}-ray studies commonly used in supernova models. The presented new rate results in an increased {sup 44}Ti production in supernovae.

Vockenhuber, C.; Buchmann, L.; Caggiano, J.; Crawford, H.; Davids, B.; Fogarty, L.; Hutcheon, D. A.; O'Connor, E.; Ottewell, D.; Pavan, M. M.; Ruiz, C.; Ruprecht, G.; Trinczek, M. [TRIUMF, 4004 Wesbrook Mall, Vancouver, British Columbia, V6T 2A3 (Canada); Ouellet, C. O.; Chen, A. A.; Pearson, J.; Wales, B. [McMaster University, Hamilton, Ontario (Canada); The, L.-S. [Department of Physics and Astronomy, Clemson University, Clemson, South Carolina (United States); D'Auria, J. M. [Simon Fraser University, Burnaby, British Columbia (Canada); Frekers, D. [Institut fuer Kernphysik, Universitaet Muenster, Muenster (Germany)] (and others)

2007-09-15

269

Experimental Identification of Spin-Parities and Single-Particle Configurations in {sup 257}No and Its {alpha}-Decay Daughter {sup 253}Fm  

SciTech Connect

{alpha}-{gamma} and {alpha}-electron coincidence spectroscopy for a short-lived heavy actinide nucleus {sup 257}No (T{sub 1/2}=24.5 s) has been performed using a gas-jet transport system and an on-line isotope separator. Spin-parities of excited states in {sup 253}Fm fed by the {alpha} decay of {sup 257}No have been identified on the basis of the measured internal conversion coefficients. The {nu}3/2{sup +}[622] configuration has been assigned to the ground state of {sup 257}No as well as to the 124.1 keV level in {sup 253}Fm. It was found that the ground-state configuration of {sup 257}No is different from that of lighter N=155 isotones.

Asai, M.; Tsukada, K.; Ichikawa, S.; Nagame, Y.; Nishinaka, I.; Akiyama, K. [Advanced Science Research Center, Japan Atomic Energy Research Institute, Tokai, Ibaraki 319-1195 (Japan); Sakama, M. [Department of Radiologic Science and Engineering, The University of Tokushima, Tokushima 770-8509 (Japan); Ishii, T.; Osa, A. [Department of Materials Science, Japan Atomic Energy Research Institute, Tokai, Ibaraki 319-1195 (Japan); Oura, Y. [Department of Chemistry, Tokyo Metropolitan University, Hachioji, Tokyo 192-0397 (Japan); Sueki, K. [Department of Chemistry, University of Tsukuba, Tsukuba, Ibaraki 305-8571 (Japan); Shibata, M. [Radioisotope Research Center, Nagoya University, Nagoya 464-8602 (Japan)

2005-09-02

270

Pattern of addition of hydroxyl radicals to the spin traps. cap alpha. -pyridyl 1-oxide N-tert-butyl nitrone. [9-MeV electrons  

SciTech Connect

Hydroxyl radicals react with ..cap alpha..-2-, ..cap alpha..-3, and ..cap alpha..-4-pyridyl 1-oxide N-tert-butyl nitrones (POBN) with rate constants of 3.2 x 10/sup 9/, 4.8 x 10/sup 9/, and 3.5 x 10/sup 9/ M/sup -1/ s/sup -1/, respectively, via addition to two distinct sites. Addition to the pyridine ring yields short-lived radicals of the hydrozyazacyclohexadienyl type, while addition to the nitrone function in the side chain yields long-lived nitroxide radicals. The distribution of OH addition at the two molecular sites was determined by using differences in reducing power upon reaction of the different types of radicals with IrCl/sub 6//sup 2 -/. The fraction of OH attack on the pyridine ring is approx. 0.6, relatively independent of the isomeric structure of the POBN.

Neta, P. (Univ. of Notre Dame, IN); Steenken, S.; Janzen, E.G.; Shetty, R.V.

1980-03-06

271

Alpha-Particle Decay Measurements for Very Long - Quasi-Stable Isotopes of Neodymium, Platinum, Samarium and Uranium.  

NASA Astrophysics Data System (ADS)

Half lives and alpha-particle energies of very long-lived (10('9) - 10('16) years) quasi-stable nuclei with A > 140 have been measured using a cylindrical gas -flow proportional counter. The source materials were deposited on the inner surface of the cathode cylinder over an area of about 1700 cm('2). Low-level counting techniques were developed with emphasis on the reduction of background from external and internal sources. External background can be reduced by shielding and rise-time discrimination. Internal background from (alpha)-contaminants in the counter materials and the source materials was a major source of background and was studied in detail. Stainless steel was found to be superior to brass and aluminum. Ultrapure source materials had to be superior to brass and aluminum. Ultrapure source materials had to be used. Half lives and energies were measured for ('144)Nd, ('147)Sm, ('190)Pt, ('234)U, ('235)U, ('238)U, and lower limit was obtained for ('148)Sm. Reduced alpha widths which describe the preformation of (alpha)-clusters in the nuclear surface were obtained for the entire region N > 82 to Z (LESSTHEQ) 84 from all available data. Systematic trends which reflect upon the nuclear structure of these nuclei make it possible to predict new short-lived proton-rich alpha emitters as well as additional very long-lived quasi-stable alpha emitters.

Al-Bataina, Barakat Atwan Mofaddi

272

Development of the dual scintillator sheet and Phoswich detector for simultaneous Alpha- and Beta-rays measurement  

SciTech Connect

Thin sheet type of ZnS(Ag)/plastic dual scintillator for simultaneous counting of alpha- and beta-particles using a organic and inorganic scintillator widely used in the radiation measurement was manufactured, which could be applicable in the contamination monitoring systems. Counting materials were manufactured by solidification of the scintillator solution which mixed scintillator, solvent, and polymer. Prepared dual scintillator is a counting material which can simultaneously measure the alpha- and beta-particles. It was divided into two parts : an inorganic scintillator layer for alpha-particle detection and an organic one for beta-particle detection. The organic layer was composed of 2,5-diphenyloxazole [PPO] and 1,4,-bis[5-phenyl(oxazolyl)benzene] [POPOP] acting as the scintillator and polysulfone acting as the polymer. The inorganic layer was composed of ZnS(Ag) as scintillator and polysulfone as paste. The ZnS(Ag) scintillator layer was printed onto the organic layer using screen printing method. To estimate the detection ability of the prepared counting materials, alpha-particle emitting nuclide, Am-241, and beta emitting nuclide, Sr/Y-90, were used. The scintillations produced by interaction between radiation and scintillator were measured by photomultiplier tube. The overall counting results reveal that the developed detector is efficient for simultaneous counting of alpha- and beta-particles. For application test, the dual scintillator was fabricated with a Phoswich detector for monitoring the in-pipe alpha and beta contamination. To deploy inside a pipe, two types of Phoswich detectors, sheets and cylinders, were prepared. For in-pipe monitoring, it was found that the cylindrical type was excellent. In the study, polymer composite counting material and Phoswich detectors were prepared using organic and inorganic scintillator for detecting different radiations. In the future, it will be applied to the contamination monitoring system for nuclear decommissioning sites, waste treatment sites, and similar areas. (authors)

Seo, B.K.; Kim, G.H.; Park, C.H.; Jung, Y.H.; Jung, C.H.; Lee, K.W. [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of); Han, M.J. [Kyungil Univ. (Korea, Republic of)

2007-07-01

273

WISE Discovered Ly-alpha Blobs at High-z: AGN Feeback Caught in the Act?  

NASA Astrophysics Data System (ADS)

Using data from the WISE mission coupled with deep optical spectroscopy, we have discovered a new population of dusty z~2 galaxies surrounded by large spatially extended Lyman-alpha emission (40-130kpc). These galaxies have redder mid-IR colors than any other population, IR luminosities of L_FIR>10^13, and are rare on the sky, implying a short-lived phase. These unique properties suggest intense AGN/supernova feedback, making them strong candidates for being one of the 'missing links' in the evolution of massive ellipticals. They provide a new regime where spatially extended Ly?alpha and large amounts of dust are likely linked at the key transition from a dusty starburst to a QSO. We request 2.5hrs of Spitzer-IRAC imaging for 12 spectroscopically confirmed WISE Ly-alpha blobs, completing the mid-IR imaging of this rare population. Spitzer is the only facilty that can probe rest-frame near-IR, where the red stellar populations peak at these redshifts. These observations are required to 1) fully sample the SED and constrain the stellar mass and dust extinction, 2) model the separate contributions from star formation and AGN, 3) determine if AGN luminosity or stellar mass correlates with Lyman-alpha, 4) place this new class of extreme object in context with the other well studied z~2 dusty galaxies.

Bridge, Carrie; Blain, Andrew; Borys, Colin; Petty, Sara; Farrah, Duncan

2012-12-01

274

Influence of cell position relative to planar alpha-particle sources on survival and preneoplastic transformation of primary rat tracheal epithelial cells  

SciTech Connect

Rat tracheal epithelial cells exposed directly on planar {sup 210}Po sources exhibited exponential cell killing; however, no significant increase in induction of preneoplastic transformation was observed over a range of {alpha}-particle fluences (0.017-0.050 {mu}m{sup {minus}2}). In contrast, up to 10-fold increases in frequencies of preneoplastic transformants, above control levels, were observed after exposure of rat tracheal epithelial cells to similar {alpha}-particle fluences on {sup 238}Pu and {sup 241}Am sources. Two alternative hypotheses are evaluated as an explanation for this apparent difference in the biological effect of {alpha} particles emitted from different sources: (a) possible interactions between effects produced by {alpha} particles and by low-energy photons, which occur with {sup 238}Pu and {sup 241}Am but not with {sup 210}Po; and (b) the influence of spatial relationships between exposed cells and the surface of the planar source. The data suggest that the cell-to-source spatial relationships affect both survival and transformation markedly. 29 refs., 4 figs., 6 tabs.

Terzaghi-Howe, M.; Turner, J.E. [Oak Ridge National Laboratory, TN (United States); Ford, J.R. [Medical Research Council, Oxon (United Kingdom)

1996-04-01

275

Alpha Thalassemia (For Parents)  

MedlinePLUS

Thalassemias Thalassemias are a group of blood disorders that affect the way the body makes hemoglobin, a ... results in that type of thalassemia. About Alpha Thalassemia Alpha thalassemia occurs when the gene that controls ...

276

Alpha-1 Antitrypsin Deficiency  

MedlinePLUS

Alpha-1 antitrypsin deficiency is an inherited disorder that can cause lung disease in adults and liver disease in adults and children. Alpha-1 antitrypsin (AAT) is a protein that protects the lungs. ...

277

Targeted alpha therapy: evidence for potential efficacy of alpha-immunoconjugates in the management of micrometastatic cancer.  

PubMed

There can be little doubt that one of the most important problems in the management of cancer is control of metastatic disease. This objective must be achieved ideally with a systemic therapeutic modality that targets cancer cells and gives minimal collateral damage to critical normal cells. The efficacy of targeted cancer therapy relies on the ability of a toxin to be located in the target cancer cell. The ideal toxin is one that is active only in the cancer cell, and not in critical normal cells. Failing this, the next best approach is a toxin with a short effective lifetime to target early stage micrometastatic disease. This rules out chemical toxins, given that they remain effective until excreted from the body, and localization of dose to the cancer cell rules out beta-emitting radio-isotopes (RI). Alpha-emitting RI, however, are much more appropriate toxins because they are short-lived and because their cytotoxicity is the result of their high rate of energy loss and short range of the alpha particles. These radionuclides have properties that are particularly suited for the elimination of single cells in transit or small nests of cancer cells. In vitro and in vivo experiments with alpha RI show dramatic superiority over beta RI. Only a few nuclear hits are needed to kill cells, and the formation of metastatic lung lesions and subcutaneous lesions in mice can be inhibited by systemic administration of alpha emitters. But alpha RI have not been able to control solid tumours, for which beta RI are better suited. A small number of alpha-emitting radionuclides are currently under investigation. These are terbium (Tb)-149, astatine (At)-211, bismuth (Bi)-212 and Bi-213. Terbium-149 and At-211 both require accelerators in close proximity to the place of application. The Bi isotopes are produced by long-lived parents and, as such, can be obtained from generators. The first phase-1 dose escalation trial with Bi-213 radioimmunoconjugate (RIC) commenced in New York in 1997, and other trials are planned with At-211 RIC and At-211 methylene blue for melanoma. Actinium (Ac)-225 is obtained from the decay of thorium (Th)-229, which is a waste product in the enrichment of fissile Th-233. Alternative accelerator production routes are being investigated, beginning with the European Centre for Nuclear Research (CERN) GeV proton spallation source. The ready and low-cost availability of the Ac:Bi generator is an important element in the implementation of clinical trials for patients with poor prognoses but without evidence of metastatic disease. PMID:10901964

Allen, B J

1999-11-01

278

The Alpha Centauri System.  

ERIC Educational Resources Information Center

Describes the Alpha Centauri star system, which is the closest star system to the sun. Discusses the difficulties associated with measurements involving Alpha Centauri, along with some of the recent advances in stellar seismology. Raises questions about the possibilities of planets around Alpha Centauri. (TW)

Soderblom, David R.

1987-01-01

279

The Alpha Centauri System.  

ERIC Educational Resources Information Center

|Describes the Alpha Centauri star system, which is the closest star system to the sun. Discusses the difficulties associated with measurements involving Alpha Centauri, along with some of the recent advances in stellar seismology. Raises questions about the possibilities of planets around Alpha Centauri. (TW)|

Soderblom, David R.

1987-01-01

280

Two methodologies for computing neutron sources from ({alpha},n) and spontaneous fission reactions in vitrified waste  

SciTech Connect

The disposal of high-level defense waste in a geologic repository necessitates conversion of the waste to a stable form. For this purpose, the Hanford Waste Vitrification Plant (HWVP) will be constructed. In this facility the waste will be converted into 6.3 {times} 10{sup 5} cm{sup 3} glassified cylinders, 59 cm in diameter and 230 cm in height, which will be placed in steel containers and buried. The waste packages must be adequately shielded to ensure the safety of personnel handling them. To calculate the shielding necessary, the radiation source term must be determined. Although the {gamma}-ray source term does not present a problem, the neutron source term is a concern. Because the glass matrix is composed of light elements, the presence of any {alpha}-particle emitting radionuclides in the waste will contribute to the neutron flux. This paper attempts to ascertain the neutron flux and spectrum from ({alpha},n) reactions and add it to the flux resulting from spontaneous fission.

Goldberg, H.J.; Morford, R.J.

1993-06-01

281

Skeletal dosimetry models for alpha-particles for use in molecular radiotherapy  

NASA Astrophysics Data System (ADS)

Molecular radiotherapy is a cancer treatment methodology whereby a radionuclide is combined with a biologically active molecule to preferentially target cancer cells. Alpha-particle emitting radionuclides show significant potential for use in molecular radiotherapy due to the short range of the alpha-particles in tissue and their high rates of energy deposition. Current radiation dosimetry models used to assess alpha emitter dose in the skeleton were developed originally for occupational applications. In medical dosimetry, individual variability in uptake, translocation and other biological factors can result in poor correlation of clinical outcome with marrow dose estimates determined using existing skeletal models. Methods presented in this work were developed in response to the need for dosimetry models which account for these biological and patient-specific factors. Dosimetry models are presented for trabecular bone alpha particle dosimetry as well as a model for cortical bone dosimetry. These radiation transport models are the 3D chord-based infinite spongiosa transport model (3D-CBIST) and the chord-based infinite cortical transport model (CBICT), respectively. Absorbed fraction data for several skeletal tissues for several subjects are presented. Each modeling strategy accounts for biological parameters, such as bone marrow cellularity, not previously incorporated into alpha-particle skeletal dosimetry models used in radiation protection. Using these data a study investigating the variability in alpha-particle absorbed fractions in the human skeleton is also presented. Data is also offered relating skeletal tissue masses in individual bone sites for a range of ages. These data are necessary for dose calculations and have previously only been available as whole body tissue masses. A revised 3D-CBIST model is also presented which allows for changes in endosteum thickness to account for revised target cell location of tissues involved in the radiological induction of bone cancer. In addition, new data are presented on the location of bone-marrow stem cells within the marrow cavities of trabecular bone of the pelvis. All results presented in this work may be applied to occupational exposures, but their greatest utility lies in dose assessments for alpha-emitters in molecular radiotherapy.

Watchman, Christopher J.

282

New measurements for the astrophysically important calcium-40(alpha,gamma)titanium-44 reaction  

NASA Astrophysics Data System (ADS)

The 40Ca(alpha,gamma)44Ti reaction is thought to be the main production method for the short-lived radionuclide, 44Ti (t1/2 = 58.9 +/- 0.3 yr). Production in the alpha-rich freeze-out zone of a core-collapse supernova makes 44Ti an important nuclide in the understanding of nucleosynthesis in explosive stellar environments. A new measurement of the 40Ca(alpha,gamma) 44Ti reaction has been performed through two different experimental approaches. During this work, a new accelerator mass spectrometry (AMS) facility was developed and commissioned at the University of Notre Dame, primarily for the measurement of reaction cross-sections of astrophysical interest. Using this facility, a series of 44Ti activation measurements were performed with a 40Ca beam incident on a 4He gas target. The four discrete energy ranges over which the activations occurred all lie within the temperature range relevant for alpha-rich freeze-out. Further to this, an excitation curve was measured over the energy range E alpha = 4600 - 3000 keV, using alpha-particles incident on a 40Ca target. The good agreement between these two results resulted in the successful commissioning of the AMS facility. The new reaction rates derived in this work results in an increased expected yield of 44Ti in proposed supernova environments (for example Cassiopeia A) by 40 %, when compared to 1D supernova models using reaction rates based on previous prompt gamma-ray studies .

Robertson, Daniel J.

283

Gamma-ray spectrum of short lived fission products  

Microsoft Academic Search

The fission products from uranium-235 irradiated by slow neutrons have been analysed using a gamma-ray scintillation spectrometer. The spectra between 40 minutes and 40 hours after irradiation for 30 seconds have been recorded and twelve major activities identified.

J R Keane

1962-01-01

284

Short-lived isomers in {sup 94}Rb  

SciTech Connect

The medium-spin structure of the neutron-rich, odd-odd nucleus {sup 94}Rb was studied by means of {gamma}-ray spectroscopy. Excited levels were populated in the neutron-induced fission of {sup 235}U and in the spontaneous fission of {sup 252}Cf and {sup 248}Cm. Two isomeric states were found at 1485.2 and 2074.8 keV with half-lives of 18 and 107 ns, respectively. The probable structures of the two isomers involve the fully aligned, proton-neutron configurations [{pi}(g{sub 9/2}) x {nu}(g{sub 7/2})]{sub 8{sup +}} and [{pi}(g{sub 9/2}) x {nu}(h{sub 11/2})]{sub 10{sup -}}, respectively. These new data give information on the single-particle energies in the region.

Tsekhanovich, I.; Dare, J. A.; Smith, A. G.; Varley, B. J. [Schuster Laboratory, University of Manchester, Manchester M13 9PL (United Kingdom); Simpson, G. S. [Laboratoire de Physique Subatomique et de Cosmologie, F-38026 Grenoble (France); Urban, W.; Soldner, T. [Institut Laue-Langevin, 6 rue J. Horowitz, F-38042 Grenoble (France); Jolie, J.; Linnemann, A. [Institut fuer Kernphysik, Universitaet zu Koeln, Zuelpicherstr. 77, D-50937 Koeln (Germany); Orlandi, R.; Smith, J. F. [University of the West of Scotland, Paisley PA1 2BE (United Kingdom); Scherillo, A. [Rutherford Appleton Laboratory, Chilton, Didcot OX11 0QX (United Kingdom); Rzaca-Urban, T.; Zlomaniec, A. [Faculty of Physics, Warsaw University, ul. Hoza 69, 00-681 Warsaw (Poland); Dorvaux, O.; Gall, B. J. P.; Roux, B. [Institut de Recherches Subatomiques, CNRS-IN2P3, F-67037 Strasbourg (France)

2008-07-15

285

Short-lived Rn-222 daughters in cryogenic liquids  

NASA Astrophysics Data System (ADS)

In this paper a detection method of ? emitters from 222Rn decay chain, present in cryogenic liquids, using bare Si-PIN diodes immersed in the liquids is presented. Properties of ionized 222Rn daughters deduced from conducted measurements are outlined. Life-time of positive ions was found to be of the order of 10 s, and nonzero content of electronegative ions was observed.

Pelczar, Krzysztof; Frodyma, Nikodem; Wjcik, Marcin

2013-08-01

286

Harvard-MIT research program in short-lived radiopharmaceuticals  

SciTech Connect

This report presents research on radiopharmaceuticals. The following topics are discussed: antibody labeling with positron-emitting radionuclides; antibody modification for radioimmune imaging; labeling antibodies; evaluation of technetium acetlyacetonates as potential cerebral blood flow agents; and studies in technetium chemistry. (CBS)

Adelstein, S.J.

1991-01-01

287

Indexing Moving Objects Using Short-Lived Throwaway Indexes  

Microsoft Academic Search

With the exponential growth of moving objects data to the Gigabyte range, it has become critical to develop effective techniques for indexing, updat- ing, and querying these massive data sets. To meet the high update rate as well as low query response time requirements of moving object applications, this pa- per takes a novel approach in moving object indexing. In

Jens Dittrich; Lukas Blunschi; Marcos Antonio Vaz Salles

2009-01-01

288

Spectroscopy of Short-Lived Fission Fragment Isomers  

NASA Astrophysics Data System (ADS)

Fission is a well-known mechanism to populate excited states in neutron-rich isotopes. Fission is also an effective tool for studying isomeric decays, as they are often well-populated and relatively easy to detect. Isomeric states with half-lives in the 5 -- 100 ?s range were examined using ^6Li-induced fission on ^232Th. A 45-MeV ^6Li beam from the 88-Inch Cyclotron of LBNL was alternately blocked to provide beam on/off periods to populate and observe the isomeric decays. Fission fragments were tagged using a thin Si detector near the ^232Th target, and coincident gamma rays were detected using six clover and one LEPS HPGe detectors of the LiBerACE array. Several isomers were identified in the A95 and A140 mass regions, as expected. Numerous isomers were also observed near A120, due to the significant contribution from symmetric fission. Characteristics of the induced fission, with observed isomer populations and decays, will be discussed.

Ressler, J. J.; Francy, C. F.; Caggiano, J. A.; Jordan, D. V.; Peplowski, P.; Warren, G. A.

2009-10-01

289

Search for Short Lived Isotopes in Volatile Reactor Fuel Products.  

National Technical Information Service (NTIS)

The volatile radioactive nuclides produced by thermal neutron fissioning of uranium oxide-polyethylene fuel of the AGN-201 Reactor were collected in an evacuated aluminum cylinder. The following constituent isotopes, identified by gamma ray spectrometry, ...

W. D. Fagan

1969-01-01

290

Harvard--MIT research program in short-lived radiopharmaceuticals  

SciTech Connect

This report describes progress on five projects. The first project showed a 1000 fold concentration of the cationic complex {sup 99m}Tc (MIBI) in heart cell mitochondria vs heart cell cytoplasm, as determined by high resolution electron probe microanalysis. Additional technetium-99m based complexes are being developed and tested. The second project involves evaluating technetium acetylacteonates as potential indicators of cerebral blood flow. An intermediate in the synthesis of a technetium porphyrin complex has been synthesized; an oxotechnetium(V)-2,4-pentanedione complex has been prepared and is currently being characterized. The third project involves using radio labelled antibodies for diagnosis and treatment of cancer. An early discovery was that chloramine-T based iodination protocols resulted in a reversal of the charge on mouse lgGs. Immunoperoxidase-labelled monoclonal antibody MOv 18 was shown to bind specifically to the most frequent ovarian aderon carcinomas, and not to healthy tissue, making this antibody a good candidate for immunotherapy or immunodetection. Work on a specific immunotherapy protocol suffered a setback when one reagent, a {sup 125}I-biotin complex, proved to be unstable in vivo. The fourth project involves labelling antibodies with positron emitting radionuclides. Radiofluorination was accomplished through reductive alkylation of {sup 18}F-aldehyde, or pentafluorophenyl esters. Radioiodination was accomplished using alkyl-tin derivation exchange. The fifth project examined antibody modification for use in radioimmune imaging. Technetium-99m-labelled lgG was shown to be biologically equivalent to Indium-III-labelled lgG for imaging focal sites of inflamation. Also, Indium III labelling of small bioactive peptides was examined as a means of imaging important physiological processes. 44 refs., 2 figs.

Not Available

1991-03-01

291

Short-lived ants take greater risks during food collection.  

PubMed

Life-history theory predicts that organisms should alter their behavior if life expectancy declines. Recent theoretical work has focused on worker life expectancy as an ultimate factor in allocating risk-related tasks among the workforce in social insects. A key prediction of this evolutionary model is that workers with shorter life expectancy should perform riskier tasks. We tested this hypothesis, using laboratory colonies of the ant Myrmica scabrinodis. We modified foraging so that it differed in level of risk by manipulating distances, temperatures, and the presence of competitors on foraging patches. The life expectancies of foragers were shortened by poisoning with carbon dioxide or by injury through removal of their propodeal spines. Both treatments significantly shortened worker life expectancy in comparison with untreated ants. We show, for the first time, that foragers with a shorter life expectancy foraged under risk more often than foragers in the control group. Thus, a worker's strategy of foraging under risky circumstances appears to be fine-tuned to its life expectancy. PMID:23149399

Moro?, Dawid; Lenda, Magdalena; Skrka, Piotr; Woyciechowski, Micha?

2012-10-19

292

Alpha-2 Adrenergic Receptor Polymorphisms.  

National Technical Information Service (NTIS)

The present invention includes polymorphisms in nucleic acids encoding the alpha-2B, alpha-2A, and alpha-2C adrenergic receptor and expressed alpha-2B, alpha2A and alpha-2C adrenergic receptor molecule. The invention also pertains to methods and molecules...

K. M. Small S. B. Liggett

2005-01-01

293

A new mechanism for DNA alterations induced by alpha particles such as those emitted by radon and radon progeny.  

PubMed Central

The mechanism(s) by which alpha (alpha) particles like those emitted from inhaled radon and radon progeny cause their carcinogenic effects in the lung remains unclear. Although direct nuclear traversals by alpha-particles may be involved in mediating these outcomes, increasing evidence indicates that a particles can cause alterations in DNA in the absence of direct hits to cell nuclei. Using the occurrence of excessive sister chromatid exchanges (SCE) as an index of DNA damage in human lung fibroblasts, we investigated the hypothesis that alpha-particles may induce DNA damage through the generation of extracellular factors. We have found that a relatively low dose of alpha-particles can result in the generation of extracellular factors, which, upon transfer to unexposed normal human cells, can cause excessive SCE to an extent equivalent to that observed when the cells are directly irradiated with the same irradiation dose. A short-lived, SCE-inducing factor(s) is generated in alpha-irradiated culture medium containing serum in the absence of cells. A more persistent SCE-inducing factor(s), which can survive freeze-thaw and is heat labile is produced by fibroblasts after exposure to the alpha-particles. These results indicate that the initiating target for alpha-particle-induced genetic changes can be larger than a cell's nucleus or even a whole cell. How transmissible factors like those observed here in vitro may extend to the in vivo condition in the context of a-particle-induced carcinogenesis in the respiratory tract remains to be determined.

Lehnert, B E; Goodwin, E H

1997-01-01

294

Rossi Alpha Method  

SciTech Connect

The Rossi Alpha Method has proved to be valuable for the determination of prompt neutron lifetimes in fissile assemblies having known reproduction numbers at or near delayed critical. This workshop report emphasizes the pioneering applications of the method by Dr. John D. Orndoff to fast-neutron critical assemblies at Los Alamos. The value of the method appears to disappear for subcritical systems where the Rossi-..alpha.. is no longer an ..alpha..-eigenvalue.

Hansen, G.E.

1985-01-01

295

Mitigation of radiation nephropathy after internal {alpha}-particle irradiation of kidneys  

SciTech Connect

Purpose: Internal irradiation of kidneys as a consequence of radioimmunotherapy, radiation accidents, or nuclear terrorism can result in radiation nephropathy. We attempted to modify pharmacologically, the functional and morphologic changes in mouse kidneys after injection with the actinium ({sup 225}Ac) nanogenerator, an in vivo generator of {alpha}- and {beta}-particle emitting elements. Methods and Materials: The animals were injected with 0.35 {mu}Ci of the {sup 225}Ac nanogenerator, which delivers a dose of 27.6 Gy to the kidneys. Then, they were randomized to receive captopril (angiotensin-converting enzyme inhibitor), L-158,809 (angiotensin II receptor-1 blocker), spironolactone (aldosterone receptor antagonist), or a placebo. Results: Forty weeks after the {sup 225}Ac injection, the placebo-control mice showed a significant increase in blood urea nitrogen (BUN) (87.6 {+-} 6.9 mg/dL), dilated Bowman spaces, and tubulolysis with basement membrane thickening. Captopril treatment accentuated the functional (BUN 119.0 {+-} 4.0 mg/dL; p <0.01 vs. placebo controls) and histopathologic damage. In contrast, L-158,809 offered moderate protection (BUN 66.6 {+-} 3.9 mg/dL; p = 0.02 vs. placebo controls). Spironolactone treatment, however, significantly prevented the development of histopathologic and functional changes (BUN 31.2 {+-} 2.5 mg/dL; p <0.001 vs. placebo controls). Conclusions: Low-dose spironolactone and, to a lesser extent, angiotensin receptor-1 blockade can offer renal protection in a mouse model of internal {alpha}-particle irradiation.

Jaggi, Jaspreet Singh [Molecular Pharmacology and Chemistry Program, Memorial Sloan-Kettering Cancer Center, New York, NY (United States); Seshan, Surya V. [Department of Pathology, Cornell University Weill Medical College, New York, NY (United States); McDevitt, Michael R. [Molecular Pharmacology and Chemistry Program, Memorial Sloan-Kettering Cancer Center, New York, NY (United States); Department of Medicine, Memorial Sloan-Kettering Cancer Center, New York, NY (United States); Sgouros, George [Department of Radiology, Johns Hopkins University School of Medicine, Baltimore, MD (United States); Hyjek, Elizabeth [Department of Pathology, Cornell University Weill Medical College, New York, NY (United States); Scheinberg, David A. [Molecular Pharmacology and Chemistry Program, Memorial Sloan-Kettering Cancer Center, New York, NY (United States) and Department of Medicine, Memorial Sloan-Kettering Cancer Center, New York, NY (United States)]. E-mail: d-scheinberg@ski.mskcc.org

2006-04-01

296

High alpha Inlets.  

National Technical Information Service (NTIS)

The high alpha inlet research effort at Lewis is part of the High Alpha Technology Program (HATP) within NASA. A key goal of HATP is to develop concepts that provide a high level of control and maneuverability for high performance aircraft at low subsonic...

R. R. Burley B. H. Anderson C. F. Smith G. J. Harloff

1991-01-01

297

Imaging alpha particle detector  

DOEpatents

A method and apparatus for detecting and imaging alpha particles sources is described. A dielectric coated high voltage electrode and a tungsten wire grid constitute a diode configuration discharge generator for electrons dislodged from atoms or molecules located in between these electrodes when struck by alpha particles from a source to be quantitatively or qualitatively analyzed. A thin polyester film window allows the alpha particles to pass into the gas enclosure and the combination of the glass electrode, grid and window is light transparent such that the details of the source which is imaged with high resolution and sensitivity by the sparks produced can be observed visually as well. The source can be viewed directly, electronically counted or integrated over time using photographic methods. A significant increase in sensitivity over other alpha particle detectors is observed, and the device has very low sensitivity to gamma or beta emissions which might otherwise appear as noise on the alpha particle signal.

Anderson, D.F.

1980-10-29

298

Event counting alpha detector  

DOEpatents

An electrostatic detector for atmospheric radon or other weak sources of alpha radiation. In one embodiment, nested enclosures are insulated from one another, open at the top, and have a high voltage pin inside and insulated from the inside enclosure. An electric field is produced between the pin and the inside enclosure. Air ions produced by collision with alpha particles inside the decay volume defined by the inside enclosure are attracted to the pin and the inner enclosure. With low alpha concentrations, individual alpha events can be measured to indicate the presence of radon or other alpha radiation. In another embodiment, an electrical field is produced between parallel plates which are insulated from a single decay cavity enclosure.

Bolton, Richard D. (Los Alamos, NM); MacArthur, Duncan W. (Los Alamos, NM)

1996-01-01

299

Angular Distribution of Alphas from Li6(d,alpha)alpha and Li7(p,alpha)alpha  

Microsoft Academic Search

The intensity of the reaction Li6(d,alpha)alpha is observed to vary with angle as 1+A(E)2theta+B(E)4theta, as expected from the Bose statistics of the product alphas, with A(E) rising gradually beginning just below 1 Mev to a broad maximum a little below unity at a bombarding energy E in the neighborhood of 2 Mev. The coefficient B(E) remains zero up to almost

N. P. Heydenburg; C. M. Hudson; D. R. Inglis; W. D. Whitehead

1948-01-01

300

High-Linear Energy Transfer Irradiation Targeted to Skeletal Metastases by the Alpha Emitter Ra-223: Adjuvant or Alternative to Conventional Modalities?  

SciTech Connect

The bone-seeking, alpha-particle emitting radiopharmaceutical Alpharadin, 223RaCl2 (t1/2 = 11.4 days) is under clinical development as a novel treatment for skeletal metastases from breast and prostate cancer. This paper summarizes the current status of preclinical and clinical research on 223RaCl2. Potential advantages of 223Ra to that of external beam irradiation or registered beta-emitting bone-seekers are discussed. Published data of 223Ra dosimetry in mice and a therapeutic study in a skeletal metastases model in nude rats have indicated significant therapeutic potential of bone-seeking alpha-emitters. This paper provides short-term and long-term results from the first clinical single dosage trial. We present data from a repeated dosage study of five consecutive injections of 50 kBq/kg bodyweight, once every third week, or two injections of 125 kBq/kg bodyweight, six weeks apart. Furthermore, preliminary results are given for a randomized phase II trial involving 64 patients with hormone-refractory prostate cancer and painful skeletal metastases who received four monthly injections of 223Ra or saline as an adjuvant to external beam radiotherapy. Also presented are preliminary dose estimates for 223Ra in humans. Results indicate that repeated dosing is feasible and that opportunities are available for combined treatment strategies.

Bruland, Oyvind S.; Nilsson, Sten; Fisher, Darrell R.; Larsen, Roy H.

2006-10-15

301

Rossi Alpha Method.  

National Technical Information Service (NTIS)

The Rossi Alpha Method has proved to be valuable for the determination of prompt neutron lifetimes in fissile assemblies having known reproduction numbers at or near delayed critical. This workshop report emphasizes the pioneering applications of the meth...

G. E. Hansen

1985-01-01

302

RAPID DETERMINATION OF 237 NP AND PU ISOTOPES IN WATER BY INDUCTIVELY COUPLED PLASMA MASS SPECTROMETRY AND ALPHA SPECTROMETRY  

SciTech Connect

A new method that allows rapid preconcentration and separation of plutonium and neptunium in water samples was developed for the measurement of {sup 237}Np and Pu isotopes by inductively-coupled plasma mass spectrometry (ICP-MS) and alpha spectrometry; a hybrid approach. {sup 238}U can interfere with {sup 239}Pu measurement by ICP-MS as {sup 238}UH{sup +} mass overlap and {sup 237}Np via peak tailing. The method provide enhanced removal of uranium by separating Pu and Np initially on TEVA Resin, then moving Pu to DGA resin for additional removal of uranium. The decontamination factor for uranium from Pu is almost 100,000 and the decontamination factor for U from Np is greater than 10,000. This method uses stacked extraction chromatography cartridges and vacuum box technology to facilitate rapid separations. Preconcentration is performed using a streamlined calcium phosphate precipitation method. Purified solutions are split between ICP-MS and alpha spectrometry so that long and short-lived Pu isotopes can be measured successfully. The method allows for simultaneous extraction of 20 samples (including QC samples) in 4 to 6 hours, and can also be used for emergency response. {sup 239}Pu, {sup 242}Pu and {sup 237}Np were measured by ICP-MS, while {sup 236}Pu, {sup 238}Pu, and {sup 239}Pu were measured by alpha spectrometry.

Maxwell, S.; Jones, V.; Culligan, B.; Nichols, S.; Noyes, G.

2010-06-23

303

Portable alpha spectrometer.  

PubMed

Many portable devices have been designed to detect ?-rays or alpha and beta particles. Most of the ?-particle detectors give the total count as a result, without identifying the radionuclides existing in the sample. The development of a device allowing rapid and straightforward ?-particle spectrometry would be very useful for detecting the radioactive contents of unknown samples. This work describes the construction of a portable device using silicon semiconductor detectors designed to rapidly detect and possibly identify alpha-emitting radionuclides. PMID:22405957

Martn Snchez, A; de la Torre Prez, J

2012-03-03

304

Precision Measurements of {alpha}s at HERA  

SciTech Connect

The precision measurements of the strong coupling constant, {alpha}s, and its energy-scale dependence carried out at HERA by the H1 and ZEUS Collaborations are reviewed. An average value of {alpha}-bars(MZ) = 0.1186 {+-} 0.0011 (exp.) {+-} 0.0050 (th.) is obtained from these measurements. The combined HERA determinations of the energy-scale dependence of {alpha}s clearly show the running of {alpha}s from jet data alone and are in agreement with the running of the coupling as predicted by QCD.

Glasman, Claudia [Universidad Autonoma de Madrid (Spain)

2005-10-06

305

Alpha particles are extremely damaging to developing hemopoiesis compared to gamma irradiation  

SciTech Connect

Estimates of risk of stochastic effects from contamination with [alpha]-particle-emitting radionuclides are based on equivalent doses which take into account the RBE of the high-LET radiation. It is assumed that the RBEs for deterministic effects are considerably less than those for stochastic effects. However, the offspring of mice injected with 30 Bq g[sup [minus]1] [sup 239]Pu at 13 days gestation develop a persistent deficit in hemopoietic stem cells which is primarily the result of damage to their regulatory microenvironment. Their spatial distribution in the marrow is also perturbed, and recent observations on those mice suggested a considerably higher factor than 20. To define a more realistic RBE for hemopoiesis, the effects of external [gamma] irradiation during the fetal development period have been compared directly with those of [sup 239]Pu incorporated via placental transfer on the development of hemopoietic tissue. Pregnant mice were irradiated with [sup 60]Co [gamma] rays (a) continuously from day 13 of gestation to birth at 0.15 or 0.6 Gy/day; (b) six repeated acute doses (0.6 Gy/min) at 0.1 or 0.3 Gy from day 13 of gestation; (c) one acute dose of 0.6 or 1.8 Gy on day 15 of gestation. The spatial distribution of hemopoietic stem cells in 8-week-old offspring was then determined and compared to that resulting from [alpha]-particle irradiation. In each case, the higher dose was required to match the results for [alpha] particles, suggesting an RBE for developing hemopoiesis of 250-360 compared to a continuous [gamma]-ray dose and a rather lower value of 130-180 compared to a single acute dose of [gamma] rays. This contrasts greatly to values for direct irradiation of the stem cells but argues that the effective RBE, measured for long-term effects in vivo, is the more realistic. It is concluded that an all-embracing factor can be grossly misleading and can greatly underestimate the risks of exposure to [alpha] particles. 21 refs., 3 figs., 1 tab.

Tie-Nan Jiang (Institute of Radiation Medicine, Tianjin (China)); Lord, B.I.; Hendry, J.H. (Paterson Institute for Cancer Research, Manchester (United Kingdom))

1994-03-01

306

Stellar Helium Burning: a Further Measurement of the Beta-Delayed Alpha-Particle Emission of (16)N  

NASA Astrophysics Data System (ADS)

The 12C(?,?)16O reaction is of critical importance for understanding stellar evolution. During helium burning this reaction competes with the triple-alpha reaction that forms carbon. The final carbon/oxygen ratio at the end of this burning stage largely determines the final stages of the star. The beta-delayed alpha-emission of 16N (i.e. prompt alpha-particles emitted from excited states of 16O populated by the slow beta-decay of 16N) has been predicted to provide a constraint on the cross section of this reaction, but requires a high sensitivity (B.R. ~ 10-9) measurement. The low energy portion of the alpha-particle spectrum has been predicted to provide a sensitive means to deduce the reduced alpha-particle width of the bound 1- state in 16O. In the past few years three attempts have been made to constrain the p-wave component of this cross section using the beta-delayed alpha-particle emission of 16N. In this work we have made a high statistics measurement of this spectrum as a continuation of our earlier low statistics Yale-UConn experiment. We have improved the statistics by a factor of more than 5, the energy resolution by 20%, and we demonstrate an understanding of our line shape from known and measured quantities. Our newly measured spectrum is compared to the three previous high statistics experiments and found to be consistent with the experimental results from Mainz and Seattle and inconsistent with those from TRIUMF. Our discrepancy with the TRIUMF results is in the width of the primary peak, with the largest differences (nearly a factor of two) near the region of the interference minimum. This region of the spectrum determines the size of the f-wave contribution to the low energy secondary maximum. This is crucial as the magnitude of the p-wave contribution only is of importance to astrophysics due to the low energy (~300 keV) that stellar helium burning occurs in massive stars. We conclude that with the current data sets the p-wave S-factor of the 12C(?,?)16O reaction cannot be determined at this stage with the accuracy (15-20%) required for the stellar evolution models developed by Woosley and Weaver.

France, Ralph Hayward, III

1997-11-01

307

Monte Carlo alpha calculation  

SciTech Connect

A Monte Carlo algorithm to efficiently calculate static alpha eigenvalues, N = ne/sup ..cap alpha..t/, for supercritical systems has been developed and tested. A direct Monte Carlo approach to calculating a static alpha is to simply follow the buildup in time of neutrons in a supercritical system and evaluate the logarithmic derivative of the neutron population with respect to time. This procedure is expensive, and the solution is very noisy and almost useless for a system near critical. The modified approach is to convert the time-dependent problem to a static ..cap alpha../sup -/eigenvalue problem and regress ..cap alpha.. on solutions of a/sup -/ k/sup -/eigenvalue problem. In practice, this procedure is much more efficient than the direct calculation, and produces much more accurate results. Because the Monte Carlo codes are intrinsically three-dimensional and use elaborate continuous-energy cross sections, this technique is now used as a standard for evaluating other calculational techniques in odd geometries or with group cross sections.

Brockway, D.; Soran, P.; Whalen, P.

1985-01-01

308

Alpha E beta 7.  

PubMed Central

alpha E beta 7 is a member of the integrin family and is expressed almost exclusively by cells of the T lymphocyte lineage in mucosal tissues. Expression is induced by transforming growth factor beta in the mucosal microenvironment. Genetic elements that control transcription are under investigation and may prove valuable for directing the expression of transgenes in mucosal T cells. The only known ligand for alpha E beta 7 is E-cadherin, which is expressed on epithelial cells. In this article, molecular aspects of ligand recognition by alpha E beta 7 in relation to recent structural data on cadherin domains are reviewed. Expression of alpha E beta 7 is often increased in inflammatory diseases, particularly where T cells infiltrate epithelial tissues. The function of alpha E beta 7 is not yet fully understood, but it is likely to be important in retention of T cells in mucosal tissues and may also have a role in cell signalling and communication between lymphocytes and epithelial surfaces.

Kilshaw, P J

1999-01-01

309

Efficacy of astatine-211-labeled monoclonal antibody in treatment of murine T-cell lymphoma  

SciTech Connect

The short-lived isotope /sup 211/At (half-life, 7.2 hr), an alpha particle-emitting halogen, has been attached to a monoclonal antibody (anti-thy 1.1, IgG1, OX7) and used in mice in the treatment of a thy 1.1 T-cell lymphoma (A120). Forty-eight hours after receiving an iv injection of 10(3) or 10(5) A120 cells, mice were treated with phosphate-buffered saline, /sup 211/At-, antibody alone, or /sup 211/At conjugated to OX7. Treatment with the /sup 211/At-labeled OX7 conjugate increased the median survival time of mice and probably cured (survival at 200 days) 6 of the 15 mice given 10(5) cells and 21 of the 27 mice given 10(3) cells.

Harrison, A.; Royle, L.

1987-01-01

310

Efficacy of astatine-211-labeled monoclonal antibody in treatment of murine T-cell lymphoma.  

PubMed

The short-lived isotope 211At (half-life, 7.2 hr), an alpha particle-emitting halogen, has been attached to a monoclonal antibody (anti-thy 1.1, IgG1, OX7) and used in mice in the treatment of a thy 1.1 T-cell lymphoma (A120). Forty-eight hours after receiving an iv injection of 10(3) or 10(5) A120 cells, mice were treated with phosphate-buffered saline, 211At-, antibody alone, or 211At conjugated to OX7. Treatment with the 211At-labeled OX7 conjugate increased the median survival time of mice and probably "cured" (survival at 200 days) 6 of the 15 mice given 10(5) cells and 21 of the 27 mice given 10(3) cells. PMID:3493441

Harrison, A; Royle, L

1987-01-01

311

Monte Carlo alpha deposition  

SciTech Connect

Prior work demonstrated the importance of nuclear scattering to fusion product energy deposition in hot plasmas. This suggests careful examination of nuclear physics details in burning plasma simulations. An existing Monte Carlo fast ion transport code is being expanded to be a test bed for this examination. An initial extension, the energy deposition of fast alpha particles in a hot deuterium plasma, is reported. The deposition times and deposition ranges are modified by allowing nuclear scattering. Up to 10% of the initial alpha particle energy is carried to greater ranges and times by the more mobile recoil deuterons. 4 refs., 5 figs., 2 tabs.

Talley, T.L.; Evans, F.

1988-01-01

312

Contribution of uranium to gross alpha radioactivity in some environmental samples in Kuwait  

SciTech Connect

This study was done in connection with the use of uranium-tipped antitank shells during the Gulf War and possible contamination of the environment of Kuwait. It was found that uranium concentrations in the soil samples ranged from 0.3 {mu}g/g to 1.85 {mu}g/g. The average value of 0.7 {mu}g/g was lower than the world average value of 2.1 {mu}g/g for surface soils. Its contribution to the total natural alpha radioactivity (excluding Rn and its short-lived daughters) varied from 1.1% to 14%. The solid fall-out samples showed higher uranium concentration which varied from 0.35 {mu}g/g to 1.73 {mu}/g (average 1.47 {mu}g/g) but its contribution to the gross alpha radioactivity was in the same range, from 1.1 to 13.2%. The difference in the concentration of uranium in suspended air matter samples during the summer of 1993 and the winter of 1994 was found to be 2.0 {mu}g/g and 1.0 {mu}g/g, respectively. The uranium contribution to the natural alpha radioactivity in these samples was in the same range but lower for the winter period. The isotopic ratio of {sup 235}U to {sup 238}U for the measured samples was basically within an experimental error of {+-}0.001, close to the theoretical value of 0.007. The calculated total annual intake of uranium via inhalation for the Kuwait population was 0.07 Bq, e.g., 0.2% of the annual limit on intake. 13 refs., 1 fig., 3 tabs.

Bou-Rabee, F. [Kuwait Univ., Safat (Kuwait); Bakir, Y.; Bem, H. [Ministry of Health, Qadsiya (Kuwait)

1995-08-01

313

Counting particles emitted by stratospheric aircraft and measuring size of particles emitted by stratospheric aircraft. Final technical report, 1 May 1990-31 December 1992  

SciTech Connect

The ER-2 condensation nuclei counter (CNC) has been modified to reduce the diffusive losses of particles within the instrument. These changes have been successful in improving the counting efficiency of small particles at low pressures. Two techniques for measuring the size distributions of particles with diameters less than 0.17 micrometers have been evaluated. Both of these methods, the differential mobility analyzer (DMA) and the diffusion battery, have fundamental problems that limit their usefulness for stratospheric applications. The authors cannot recommend either for this application. Newly developed, alternative methods for measuring small particles include inertial separation with a low-loss critical orifice and thin-plate impactor device. This technique is now used to collect particles in the multisample aerosol collector housed in the ER-2 CNC-2, and shows some promise for particle size measurements when coupled with a CNC as a counting device. The modified focused-cavity aerosol spectrometer (FCAS) can determine the size distribution of particles with ambient diameters as small as about 0.07 micrometers. Data from this instrument indicates the presence of a nuclei mode when CNC-2 indicates high concentrations of particles, but cannot resolve important parameters of the distribution.

Wilson, J.C.

1994-04-01

314

Enhanced killing of cervical cancer cells by combinations of methyl jasmonate with cisplatin, X or alpha radiation.  

PubMed

Current therapies for treatment of advanced cervical cancer involve the use of cisplatin, often in combination with radiotherapy. These treatments do not lead to a high survival rate and furthermore, serious side effects are dose-limiting factors. Methyl jasmonate (MJ) was recently identified as potent and selective cytotoxic agent towards cervical cancer cells. In the present study we evaluated the effectiveness of combined treatments of MJ with cisplatin or X-irradiation on a variety of cervical cancer cells including SiHa, CaSki, HeLa and C33A. Cytotoxicity of alpha particles, emitted from (224)Ra atoms, was also evaluated as a single agent and in combination with MJ. Cooperation between MJ and cisplatin in reducing cell viability (XTT assays) and survival (clonogenicity assays) was exhibited towards several cancer cell lines at a range of combination doses. MJ effectively cooperated also with X-ray irradiation, significantly lowering the radiation doses required to inhibit cell survival (ID50) of all tested cells lines. We show for the first time, that alpha irradiation selectively reduced cell viability and survival of cervical cancer cells. Lower doses of ? irradiation were required as compared to X-irradiation to inhibit cell survival. Cooperation with MJ was demonstrated in part of the cancer cell lines. In conclusion, our studies point to ? irradiation and MJ, novel anticancer agents, as potent candidates for treatment of cervical cancer, in single agent regiments and in combination. MJ can be added also to conventional X-ray and cisplatin therapies to increase their cytotoxic effect while lowering the effective dose. PMID:22956285

Milrot, Elad; Jackman, Anna; Flescher, Eliezer; Gonen, Pinhas; Kelson, Itzhak; Keisari, Yona; Sherman, Levana

2012-09-06

315

Hypoglycaemic activity of alpha, alpha trehalose-6-phosphate.  

PubMed

Alpha-alpha-trehalose-6-phosphate, synthesized by Oke was screened for hypoglycaemic activity. Alloxan-induced diabetic albino rats and fasted-rabbits were used in the study. The inhibitory activity of trehalose-6-phosphate on trehalase was also assayed. The study shows that alpha-alpha-trehalose-6-phosphate is a glucose analogue with potent anti-hyperglcaemic activity as shown by its hypoglycaemic response in fasted rabbits. The ability of alpha-alpha-trehalose-6-phosphate to attenuate the diabetic toxicity in alloxan-induced diabetic rats confirmed its potent anti-diabetic activity. The mechanism of action of this synthesized compound may be linked with its ability to inhibit trehalase, and increase the activity of the superoxidase dimutase present in the beta-cells of the alloxan-diabetic rats and also being a glucose analogue according to Puls principle, alpha-alpha-trehalose-6-phosphate is able to influence the intermediate metabolism of carbohydrate. PMID:10497653

Oke, J M; Watt, R A

316

Rossi Alpha Method  

Microsoft Academic Search

The Rossi Alpha Method has proved to be valuable for the determination of prompt neutron lifetimes in fissile assemblies having known reproduction numbers at or near delayed critical. This workshop report emphasizes the pioneering applications of the method by Dr. John D. Orndoff to fast-neutron critical assemblies at Los Alamos. The value of the method appears to disappear for subcritical

1985-01-01

317

Alpha-mannosidosis  

Microsoft Academic Search

Alpha-mannosidosis is an inherited lysosomal storage disorder characterized by immune deficiency, facial and skeletal abnormalities, hearing impairment, and intellectual disability. It occurs in approximately 1 of 500,000 live births. The children are often born apparently normal, and their condition worsens progressively. Some children are born with ankle equinus or develop hydrocephalus in the first year of life. Main features are

Dag Malm; ivind Nilssen

2008-01-01

318

Structure of alpha Gete.  

National Technical Information Service (NTIS)

The parameters in the crystal structure of alpha-GeTe were determined by least-squares analysis of intensity data obtained with an automatic x-ray powder diffractometer. The rhombohedral cell containing 4 Ge and 4 Te atoms has a=5.996 plus or minus 0.001 ...

J. Goldak C. S. Barrett D. Innes W. Youdelis

1965-01-01

319

[alpha]-Oxocarboxylic Acids  

ERIC Educational Resources Information Center

|Several [alpha]-oxocarboxylic acids play key roles in metabolism in plants and animals. However, there are inconsistencies between the structures as commonly portrayed and the reported acid ionization constants, which result because the acids are predominantly hydrated in aqueous solution; that is, the predominant form is RC(OH)[subscript 2]COOH

Kerber, Robert C.; Fernando, Marian S.

2010-01-01

320

Pressure effects on the alpha and alpha' relaxations in polymethylphenylsiloxane  

Microsoft Academic Search

In some polymers, in addition to the usual structural alpha relaxation, a slower alpha' relaxation is observed with a non-Arrhenius temperature dependence. In order to understand better the molecular origin of this alpha' relaxation in poly(methylphenylsiloxane) (PMPS) we have studied, for the first time, the pressure dependence of its relaxation time, together with the usual temperature dependence, by means of

H. Kriegs; J. Gapinski; G. Meier; M. Paluch; S. Pawlus; A. Patkowski

2006-01-01

321

Alpha-1 Antitrypsin Deficiency: Inherited Liver Disease  

MedlinePLUS

... View full profile Alpha-1 Antitrypsin Deficiency: Inherited Liver Disease The inherited condition alpha-1 antitrypsin deficiency can cause liver disease in children and adults. Alpha-1 antitrypsin ...

322

Alpha Numeric Symbol Generation Equipment.  

National Technical Information Service (NTIS)

Hazeltine has developed and installed two Alpha Numeric Generator equipments in the FAA Atlanta and Indianapolis Air Traffic Control Centers. These equipments have passed all acceptance tests and are undergoing operation testing. These Alpha Numeric Gener...

J. F. O'Connor

1965-01-01

323

Alpha Numeric Symbol Generation Equipment.  

National Technical Information Service (NTIS)

Two Alpha Numeric Generator equipments in the FAA Atlanta and Indianapolis Air Traffic Control Centers passed all acceptance tests and are undergoing operation testing. These Alpha Numeric Generators electronically label aircraft radar blips on air traffi...

J. F. O'Connor

1965-01-01

324

Summary of Alpha Particle Transport  

SciTech Connect

This paper summarizes the talks on alpha particle transport which were presented at the 5th International Atomic Energy Agency's Technical Committee Meeting on "Alpha Particles in Fusion Research" held at the Joint European Torus, England in September 1997.

Medley, S.S.; White, R.B.; Zweben, S.J.

1998-08-19

325

Prompt detection of alpha particles from 210Po: another clue to the origin of rock varnish?  

PubMed

Alpha particles have been measured coming from the surfaces of rocks covered with dark red-brown rock varnish, as well as rocks that appear to have little, if any, varnish. A pronounced peak at 5.3 MeV indicates the presence of 210Po, a short-lived natural-radioactive element. Surface activities for 33 samples range from 0.008 Bq/cm2 to 0.065 Bq/cm2. It is estimated that this nuclide is concentrated 10(11) times in these paper-thin coatings above its concentration in ground-level air. Gamma rays from the decay of 137Cs, a product of testing nuclear weapons some 50 years ago, were also detected. Analysis of samples of varnish stripped from the rock revealed traces of 239,240Pu and 238Pu. The presence of all of these isotopes strongly supports the theory that varnish films derive their building blocks from the atmosphere and, with time, all rocks in arid environments will become coated. PMID:15511566

Hodge, Vernon F; Farmer, Dennis E; Diaz, Tammy; Orndorff, Richard L

2005-01-01

326

Gamma-Ray-Multiplicity Measurements for (alpha,p), (alpha,alpha'), (d,alpha), (p,alpha), (d,p), and (p,p') Reactions  

Microsoft Academic Search

Using a method introduced previously measurements were made of the gamma-ray multiplicity Ngamma (the average number of gamma rays emitted in the decay of residual nuclei left by nuclear reactions) as a function of excitation energy E* for (p,alpha) and (d,alpha) reactions on 51V, 56Fe, and 57Fe targets; (alpha,p) reactions on 51V, 56Fe, 57Fe, 58Ni, 64Ni, 93Nb, and Ag; (alpha,alpha')

J. H. Degnan; B. L. Cohen; G. R. Rao; K. C. Chan; L. Shabason

1973-01-01

327

I. Excluded volume effects in Ising cluster distributions and nuclear multifragmentation. II. Multiple-chance effects in alpha-particle evaporation  

NASA Astrophysics Data System (ADS)

In Part I, geometric clusters of the Ising model are studied as possible model clusters for nuclear multifragmentation. These clusters may not be considered as non-interacting (ideal gas) due to excluded volume effect which predominantly is the artifact of the cluster's finite size. Interaction significantly complicates the use of clusters in the analysis of thermodynamic systems. Stillinger's theory is used as a basis for the analysis, which within the RFL (Reiss, Frisch, Lebowitz) fluid-of-spheres approximation produces a prediction for cluster concentrations well obeyed by geometric clusters of the Ising model. If thermodynamic condition of phase coexistence is met, these concentrations can be incorporated into a differential equation procedure of moderate complexity to elucidate the liquid-vapor phase diagram of the system with cluster interaction included. The drawback of increased complexity is outweighted by the reward of greater accuracy of the phase diagram, as it is demonstrated by the Ising model. A novel nuclear-cluster analysis procedure is developed by modifying Fisher's model to contain cluster interaction and employing the differential equation procedure to obtain thermodynamic variables. With this procedure applied to geometric clusters, the guidelines are developed to look for excluded volume effect in nuclear multifragmentation. In Part II, an explanation is offered for the recently observed oscillations in the energy spectra of alpha-particles emitted from hot compound nuclei. Contrary to what was previously expected, the oscillations are assumed to be caused by the multiple-chance nature of alpha-evaporation. In a semi-empirical fashion this assumption is successfully confirmed by a technique of two-spectra decomposition which treats experimental alpha-spectra as having contributions from at least two independent emitters. Building upon the success of the multiple-chance explanation of the oscillations, Moretto's single-chance evaporation theory is augmented to include multiple-chance emission and tested on experimental data to yield positive results.

Breus, Dimitry Eugene

328

I. Excluded Volume Effects in Ising Cluster Distributions and Nuclear Multifragmentation II. Multiple-Chance Effects in Alpha-Particle Evaporation  

SciTech Connect

In Part 1, geometric clusters of the Ising model are studied as possible model clusters for nuclear multifragmentation. These clusters may not be considered as non-interacting (ideal gas) due to excluded volume effect which predominantly is the artifact of the cluster's finite size. Interaction significantly complicates the use of clusters in the analysis of thermodynamic systems. Stillinger's theory is used as a basis for the analysis, which within the RFL (Reiss, Frisch, Lebowitz) fluid-of-spheres approximation produces a prediction for cluster concentrations well obeyed by geometric clusters of the Ising model. If thermodynamic condition of phase coexistence is met, these concentrations can be incorporated into a differential equation procedure of moderate complexity to elucidate the liquid-vapor phase diagram of the system with cluster interaction included. The drawback of increased complexity is outweighted by the reward of greater accuracy of the phase diagram, as it is demonstrated by the Ising model. A novel nuclear-cluster analysis procedure is developed by modifying Fisher's model to contain cluster interaction and employing the differential equation procedure to obtain thermodynamic variables. With this procedure applied to geometric clusters, the guidelines are developed to look for excluded volume effect in nuclear multifragmentation. In part 2, an explanation is offered for the recently observed oscillations in the energy spectra of {alpha}-particles emitted from hot compound nuclei. Contrary to what was previously expected, the oscillations are assumed to be caused by the multiple-chance nature of {alpha}-evaporation. In a semi-empirical fashion this assumption is successfully confirmed by a technique of two-spectra decomposition which treats experimental {alpha}-spectra has having contributions from at least two independent emitters. Building upon the success of the multiple-chance explanation of the oscillations, Moretto's single-chance evaporation theory is augmented to include multiple-chance emission and tested on experimental data to yield positive results.

Breus, Dimitry E.

2005-05-16

329

AlphaGalileo  

NSDL National Science Digital Library

Billed as "The world's leading resource for European research", AlphaGalileo is a tremendous resource for those with a penchant for keeping tabs on Continental scholarship that deals with science, art, technology, health, society, and the humanities. The team at AlphaGalileo includes a multilingual group of specialists and their coverage is very broad, a fact that will be welcomed in many quarters. Visitors need to complete a brief registration before using the site, and after that they can browse and search through the materials offered here. The site also allows users to perform thematic searches and the opportunity to look over press releases. It's also worth noting that after logging in, visitors can also post their own items.

330

Growth retardation and destruction of experimental squamous cell carcinoma by interstitial radioactive wires releasing diffusing alpha-emitting atoms.  

PubMed

In the present study, we examined the antitumoral effects caused by the release of alpha emitting radioisotopes into solid squamous cell carcinoma (SCC) tumors. Using a novel method termed DART (Diffusing Alpha-emitters Radiation Therapy), we assessed the efficacy of short-lived daughters of (224)Ra releasing alpha particles, dispersing in the malignant tissue, to cause tumor growth retardation and destruction. It was carried out using specially designed wires loaded with (224)Ra activities in the range of 7-42 kBq in a set of experiments performed on BALB/c and nude mice bearing metastatic SCC tumors derived from either mouse SQ2 or human CAL27 cell lines. The insertion of a DART wire to the center of 6-7 mm primary tumors, retarded tumor growth, reduced lung metastatic load, prolonged life expectancy and in some cases caused tumor eradication. These effects were enhanced either when treating smaller tumors or treating identical tumors with 2 DART wires. Similar experiments on human-derived SCC tumors in nude mice were consistent with the outcomes of the murine model. Histological assessments revealed the tissue damage pattern, and indicated a role for the tumor vasculature in the dispersion of the atoms and the propagation of the damage. Our findings indicate that Diffusing Alpha-emitting Radiation Therapy is effective in a model system using SCC primary tumors. The in situ destruction of primary solid tumors by DART is evidently a necessary step toward curing cancer and might be augmented by chemotherapy and other modalities such as immunotherapy or antigrowth factors agents. PMID:18059026

Cooks, Tomer; Arazi, Lior; Schmidt, Michael; Marshak, Gideon; Kelson, Itzhak; Keisari, Yona

2008-04-01

331

ALPHA SPILLOVER DEPENDS ON ALPHA ENERGY: A NEW FINDING IN ALPHA\\/BETA LIQUID SCINTILLATION SPECTROMETRY  

Microsoft Academic Search

The calibration of the alpha\\/beta liquid scintillation (LS) spectrometric measurement is rather complicated for samples having variable chemical and radionuclide compositions if rather accurate results are required. Variable quenching can be a significant source of uncertainty if it is not considered in the calibrations because variable quenching affects alpha and beta spillovers, the optimum pulse-shape analyzer (PSA), and alpha and

Laina Salonen

332

Pressure effects on the alpha and alpha' relaxations in polymethylphenylsiloxane.  

PubMed

In some polymers, in addition to the usual structural alpha relaxation, a slower alpha' relaxation is observed with a non-Arrhenius temperature dependence. In order to understand better the molecular origin of this alpha' relaxation in poly(methylphenylsiloxane) (PMPS) we have studied, for the first time, the pressure dependence of its relaxation time, together with the usual temperature dependence, by means of dynamic light scattering (DLS). For the same material the alpha relaxation was also studied by means of DLS and dielectric spectroscopy (DS) in broad temperature and pressure ranges. We find that the temperature dependence of both alpha and alpha' relaxation times, at all pressures studied, can be described by a double Vogel-Fulcher-Tammann (VFT) law. The pressure dependence of the characteristic temperatures Tg (glass transition temperature) and T0 (Vogel temperature) as well as the activation volumes for both alpha and alpha' processes are very similar, indicating, that both relaxation processes originate from similar local molecular dynamics. Additionally, for both alpha and alpha' relaxations the combined temperature and pressure dependences of the relaxation times can be described using a parameter Gamma=rhon/T with the same value of the exponent n. PMID:16542098

Kriegs, H; Gapinski, J; Meier, G; Paluch, M; Pawlus, S; Patkowski, A

2006-03-14

333

Induction of lymphoma and osteosarcoma in mice by single and protracted low alpha doses  

SciTech Connect

Internal doses from the short-lived alpha-emitter 22Ra were given to 4-wk-old female mice. One group of about 300 animals received a single injection of 18.5 kBq 22Ra kg-1 body weight, corresponding to a mean skeletal alpha dose of 0.15 Gy. A second group of about 300 animals received the same total amount of 224Ra in the form of 72 fractions of 257 Bq kg-1 each, applied twice weekly during 36 wk. The fractionated group received the same final mean total skeletal dose of 0.15 Gy as the single injected group, but with a mean skeletal dose rate of 1 mGy d-1. A rather high incidence, 13.5% (40/296), of early malignant lymphomas was observed in the fractionated group during and shortly after the injection period, followed by a 7% incidence (21/296) of osteosarcomas during the second half of the animals' lifetime. The group with a single injection did not develop early lymphomas but did develop osteosarcomas later with an incidence of 5.8% (17/295). The occurrence of osteosarcomas was similar up to day 800 in the two experimental groups. Surprisingly, however, after this period no additional case of osteosarcoma was observed in the single-injected group, whereas one-third of all osteosarcomas occurred after day 800 in the protracted group. The additional later occurrence of osteosarcomas occurred after indicates a longer lasting induction effect on osteosarcomas, or a promoting effect in older age, for this kind of treatment.

Mueller, W.A.L.; Luz, A.; Murray, A.B.; Linzner, U. (Gesellschaft fuer Strahlen- und Umweltforschung, Neuherberg (Germany, F.R.))

1990-09-01

334

Alpha-mannosidosis  

PubMed Central

Alpha-mannosidosis is an inherited lysosomal storage disorder characterized by immune deficiency, facial and skeletal abnormalities, hearing impairment, and intellectual disability. It occurs in approximately 1 of 500,000 live births. The children are often born apparently normal, and their condition worsens progressively. Some children are born with ankle equinus or develop hydrocephalus in the first year of life. Main features are immune deficiency (manifested by recurrent infections, especially in the first decade of life), skeletal abnormalities (mild-to-moderate dysostosis multiplex, scoliosis and deformation of the sternum), hearing impairment (moderate-to-severe sensorineural hearing loss), gradual impairment of mental functions and speech, and often, periods of psychosis. Associated motor function disturbances include muscular weakness, joint abnormalities and ataxia. The facial trait include large head with prominent forehead, rounded eyebrows, flattened nasal bridge, macroglossia, widely spaced teeth, and prognathism. Slight strabismus is common. The clinical variability is significant, representing a continuum in severity. The disorder is caused by lysosomal alpha-mannosidase deficiency. Alpha-mannosidosis is inherited in an autosomal recessive fashion and is caused by mutations in the MAN2B1 gene located on chromosome 19 (19 p13.2-q12). Diagnosis is made by measuring acid alpha-mannosidase activity in leukocytes or other nucleated cells and can be confirmed by genetic testing. Elevated urinary secretion of mannose-rich oligosaccharides is suggestive, but not diagnostic. Differential diagnoses are mainly the other lysosomal storage diseases like the mucopolysaccharidoses. Genetic counseling should be given to explain the nature of the disease and to detect carriers. Antenatal diagnosis is possible, based on both biochemical and genetic methods. The management should be pro-active, preventing complications and treating manifestations. Infections must be treated frequently. Otolaryngological treatment of fluid in the middle ear is often required and use of hearing aids is invariably required. Early educational intervention for development of social skills is needed and physiotherapy is important to improve bodily function. Orthopedic surgery may be necessary. The long-term prognosis is poor. There is an insidiously slow progression of neuromuscular and skeletal deterioration over several decades, making most patients wheel-chair dependent. No patients manage to be completely socially independent. Many patients are over 50 years of age.

Malm, Dag; Nilssen, ?ivind

2008-01-01

335

Finite Range Effects in (alpha, 2alpha) Reactions  

SciTech Connect

Finite range calculations for the (alpha, 2alpha) reactions are performed for the first time to remove huge inconsistencies obtained earlier in conventional zero range analyses. Vagaries of the energy dependent experimental observations up to 200 MeV are understood using the well-established nuclear radii and distorting optical potentials. The results are found to be sensitive to the short distance behavior of the alpha-alpha interaction, indicating the utility of the knockout reactions as a probe of the knockout vertex at short distances. Our approach paves the way to include finite range effects in atomic and molecular physics as also in neutron multiplication calculations.

Jain, Arun K.; Joshi, Bhushan N. [Nuclear Physics Division, Bhabha Atomic Research Center, Mumbai-400 085 (India)

2009-09-25

336

Drosophila melanogaster importin alpha1 and alpha3 can replace importin alpha2 during spermatogenesis but not oogenesis.  

PubMed Central

Importin alpha's mediate the nuclear transport of many classical nuclear localization signal (cNLS)-containing proteins. Multicellular animals contain multiple importin alpha genes, most of which fall into three conventional phylogenetic clades, here designated alpha1, alpha2, and alpha3. Using degenerate PCR we cloned Drosophila melanogaster importin alpha1, alpha2, and alpha3 genes, demonstrating that the complete conventional importin alpha gene family arose prior to the split between invertebrates and vertebrates. We have begun to analyze the genetic interactions among conventional importin alpha genes by studying their capacity to rescue the male and female sterility of importin alpha2 null flies. The sterility of alpha2 null males was rescued to similar extents by importin alpha1, alpha2, and alpha3 transgenes, suggesting that all three conventional importin alpha's are capable of performing the important role of importin alpha2 during spermatogenesis. In contrast, sterility of alpha2 null females was rescued only by importin alpha2 transgenes, suggesting that it plays a paralog-specific role in oogenesis. Female infertility was also rescued by a mutant importin alpha2 transgene lacking a site that is normally phosphorylated in ovaries. These rescue experiments suggest that male and female gametogenesis have distinct requirements for importin alpha2.

Mason, D Adam; Fleming, Robert J; Goldfarb, David S

2002-01-01

337

Alpha-particle microdosimetry.  

PubMed

With the increasing availability of alpha emitters, targeted ?-particle therapy has emerged as a solution of choice to treat haematological cancers and micrometastatic and minimal residual diseases. Alpha-particles are highly cytotoxic because of their high linear energy transfer (LET) and have a short range of a few cell diameters in tissue, assuring good treatment specificity. These radiologic features make conventional dosimetry less relevant for that context. Stochastic variations in the energy deposited in cell nuclei are important because of the microscopic target size, low number of ?- particle traversals, and variation in LET along the ?-particle track. Microdosimetry provides a conceptual framework that aims at a systematic analysis of the stochastic distribution of energy deposits in irradiated matter. The different quantities of microdosimetry and the different methods of microdosimetric calculations were described in the early eighties. Since then, numerous models have been published through the years and applied to analyse experimental data or to model realistic therapeutic situations. Major results have been an accurate description of the high toxicity of ?-particles, and the description of the predominant effect of activity distribution at the cellular scale on toxicity or efficacy of potential targeted ?-particle therapies. This last factor represents a major limitation to the use of microdosimetry in vivo because determination of the source - target distribution is complicated. The future contributions of microdosimetry in targeted ?-particle therapy research will certainly depend on the ability to develop high-resolution detectors and on the implementation of pharmaco-kinetic models at the tumour microenvironment scale. PMID:22201713

Chouin, Nicolas; Bardies, Manuel

2011-07-01

338

Systematics of Alpha-Radioactivity  

Microsoft Academic Search

Correlations of alpha-decay energies in terms of mass number and atomic number have been made for all of the alpha-emitting species now numbering over 100. For each element isotopes show increase in alpha-energy with decrease in mass number except in the region of 126 neutrons where there is an explainable reversal. This reversal has the effect of creating a region

I. Perlman; A. Ghiorso; G. T. Seaborg

1949-01-01

339

Systematics of Alpha-Radioactivity  

Microsoft Academic Search

Correlations of alpha-decay energies in terms of mass number and atomic number have been made for all of the alpha-emitting species now numbering over 100. For each element isotopes show increase in alpha-energy with decrease in mass number except in the region of 126 neutrons where there is an explainable reversal. This reversal has the effect of creating a region

I. Perlman; A. Ghiorso; G. T. Seaborg

1950-01-01

340

Prothymosin alpha in Human Blood  

Microsoft Academic Search

The major cross-reacting peptide in human plasma detected with a radioimmunoassay (RIA) for thymosin alpha 1 was identified as prothymosin alpha , based on its elution properties in gel-filtration chromatography and its amino acid composition after purification by HPLC. A small quantity (<10%) of the total cross-reacting material was recovered in fractions corresponding to lower molecular weight thymosin alpha 1-like

C. Panneerselvam; A. A. Haritos; J. Caldarella; B. L. Horecker

1987-01-01

341

Alpha particle confinement in tokamaks  

SciTech Connect

An assessment of diffusive tokamak transport mechanisms of concern for alpha particles indicates that the ''stochastic regime'' is the only one which appears to pose a real danger for adequate alpha confinement. This fact, in conjunction with the threshold character of that mechanism, allows one to decide whether an alpha born at a given location will be lost or confined, according to a very simple criterion. Implementing this criterion numerically results in a new code for the assessment of alpha confinement, which is orders of magnitude faster than earlier codes used for this purpose. 13 refs., 3 figs., 1 tab.

White, R.B.; Mynick, H.E.

1988-11-01

342

Alpha Magnetic Spectrometer  

NASA Astrophysics Data System (ADS)

The Alpha Magnetic Spectrometer (AMS) is a precision particle physics magnetic spectrometer designed to measure electrons, positrons, gamma rays and various nuclei and anti-nuclei from the cosmos up to TeV energy ranges. AMS weighs 7.5 tons and measures 5 meters by 4 meters by 3 meters. It contains 300,000 channels of electronics and 650 onboard microprocessors. It was delivered to the International Space Station onboard space shuttle Endeavour and installed on May 19, 2011. Since that time, more than 14 billion cosmic ray events have been collected. All the detectors function properly. At this moment, we are actively engaged in data analysis. AMS is an international collaboration involving 16 countries and 60 institutes. It took 16 years to construct and test. AMS is the only major physical science experiment on the International Space Station and will continue to collect data over the entire lifetime of the Space Station (10-20 years).

Ting, Samuel

2012-07-01

343

Alpha olefin oligomerization catalyst  

SciTech Connect

This patent describes a catalyst active for oligomerizing one or more oligomerizable alpha olefin monomers in a hydrocarbon solvent to produce linear olefin oligomers of from about 4 to about 20 carbon atoms. It comprises an organometallic compound wherein the metal thereof is selected from the group consisting of zinc, magnesium, and aluminum, in combination with the reaction mixture obtained by reacting in a hydrocarbon, a zirconium compound of the formula ZrX{sub n}Y{sub 4{minus}n} wherein X is a halogen, Y is selected from the group consisting of aryloxides, alkoxides, and carboxylates, and n ranges from 1 to 4, inclusive, and a basic salt of a carboxylic acid.

Fries, R.W.

1992-05-26

344

Lyman Alpha Tomography  

NASA Astrophysics Data System (ADS)

Narrow-band filters are often used to find emission-line galaxies at predetermined redshifts. When applied to high-redshift Lyman Alpha Emitting galaxies, typical surveys include galaxies over a redshift range of delta_z=0.1. We show that narrow-band filters with overlapping bandpasses can be used to pinpoint the redshifts of emission-line galaxies to much higher precision, by performing tomography using the ratio of fluxes between the two filters to identify the precise wavelength where the emission line falls. We report an empirical test of this technique, using deep NB4990 and NB5015 Angstrom MUSYC images of the Extended Chandra Deep Field-South obtained at the CTIO 4m telescope (Gawiser et al. 2006, Ciardullo et al. 2011.) While formally a type of photometric redshift, Lyman Alpha Tomography allows the redshifts of these galaxies to be determined to delta_z/(1+z)=0.002, which is the same precision achievable with low-resolution (R=100) spectrographs for these dim, single-emission-line galaxies. Determining the redshifts reveals emission-line luminosities and, when combined with broadband imaging, equivalent widths (EW). Hence this technique enables large galaxy redshift surveys that simultaneously reveal emission-line galaxy luminosity functions and EW distributions without the need to perform resource-intensive spectroscopy. We discuss how the technique can be employed on next generation wide-field imagers, including DECam, Hyper Suprime Cam, and ODI. This material is based upon work supported by the National Science Foundation under Grant Nos. 0807570, 0807885, 1055919, and by DOE grants DE-GF02-08ER41560 and DE-FG02-08ER41561.

Gawiser, Eric J.; Kanarek, G.; Ciardullo, R.; Gronwall, C.; MUSYC Collaboration

2012-05-01

345

Evaluation of internal alpha-particle radiation exposure and subsequent fertility among a cohort of women formerly employed in the radium dial industry  

SciTech Connect

This study examined the effect of internal exposure to {alpha}-particle radiation on subsequent fertility among women employed in radium dial industry prior to 1930, when appreciable amounts of radium were often ingested through the practice of pointing the paint brush with the lips. The analysis was limited to women for whom a radium body burden measurement had been obtained and who were married prior to age 45 (n = 603). Internal radiation dose to the ovary was calculated based on initial intakes of radium-226 and radium-228, average ovarian mass, number and energy of {alpha} particles emitted, fraction of energy absorbed within the ovary, effective retention integrals and estimated photon irradiation. Time between marriage and pregnancy, number of pregnancies and number of live births served as surrogates for fertility. Radiation appeared to have no effect on fertility at estimated cumulative ovarian dose equivalents below 5 Sv; above this dose, however, statistically significant declines in both number of pregnancies and live births were observed. These trends persisted after multivariable adjustment for potential confounding variables and after exclusion of subjects contributing a potential classification or selection bias to the study. Additionally, the high-dose group experienced fewer live births than would have been expected based on population rates. There were no differences in time to first pregnancy between high- and low-dose groups. These results are consistent with earlier studies of {gamma}-ray exposures and suggest that exposure to high doses of radiation from internally deposited radium reduces fertility rather than inducing sterility. 42 refs., 5 tabs.

Schieve, L.A.; Davis, F.; Freels, S. [Univ. of Illinois, Chicago, IL (United States)] [and others

1997-02-01

346

Evaluation of internal alpha radiation exposure and subsequent infertility among a cohort of women formerly employed in the radium dial industry.  

SciTech Connect

This study examined the effect of internal exposure to {alpha}-particle radiation on subsequent fertility among women employed in the radium dial industry prior to 1930, when appreciable amounts of radium were often ingested through the practice of pointing the paint brush with the lips. The analysis was limited to women for whom a radium body burden measurement had been obtained and who were married prior to age 45 (n=603). Internal radiation dose to the ovary was calculated based on initial intakes of radium-226 and radium-228, average ovarian mass, number and energy of {alpha} particles emitted, fraction of energy absorbed with in the ovary, effective retention integrals and estimated photon irradiation. Time between marriage and pregnancy, number of pregnancies and number of live births served as surrogates for fertility. Radiation appeared to have no effect on fertility at estimated cumulative ovarian dose equivalents below 5 Sv; above this dose, however, statistically significant declines in both number of pregnancies and live births were observed. These trends persisted after multivariable adjustment for potential confounding variables and after exclusion of subjects contributing a potential classification or selection bias to the study. Additionally, the high-dose group experienced fewer live births than would have been expected based on population rates. There were no differences in time to first pregnancy between high- and low-dose groups. These results are consistent with earlier studies of {gamma}-ray exposures and suggest that exposure to high doses of radiation from internally deposited radium reduces fertility rather than inducing sterility.

Schieve, L. A.; Davis, F.; Roeske, J.; Handler, A.; Freels, S.; Stinchcomb, T.; Keane, A.; Environmental Research; Univ. of Illinois at Chicago; Univ. of Chicago; DePaul Univ.

1997-02-01

347

Intratumour injection of immunoglobulins labelled with the alpha-particle emitter 211At: analyses of tumour retention, microdistribution and growth delay.  

PubMed Central

To determine the effects of 211At-labelled antibodies in solid tumour tissue, nude mice carrying OHS human osteosarcoma xenografts received intratumour injections at dosages of 1, 2 or 4 MBq (-1) tumour. The radioisotope was conjugated to either the osteosarcoma-specific monoclonal antibody TP-3 or the non-specific polyclonal antibody hlgGkappa. Tumour retention of injected radioimmunoconjugate (RIC), measured as the percentage of injected activity dosage per gram, was significantly higher for the [211At]TP-3 (203 +/- 93 at 24.1 h post injection) compared with the [211At]hlgGkappa (57 +/- 22 at 23.2 h post injection). The radioactive count rates in body (measured at neck and abdomen) were significantly lower with the TP-3 than with the hlgGkappa. Microautoradiography of the tumour radionuclide distribution was different for the two RICs, i.e. the [211At]TP-3 was to a larger extent concentrated near the injection site, whereas the [211At]hlgGkappa was more evenly distributed all over the tumour. The tumour growth was significantly delayed as a function of the injected activity dosage but without significant difference between the specific and the non-specific RIC. According to this study, it is possible to deliver highly selective radiation doses to solid tumours using intratumour injection of alpha-particle-emitting RICs. Improved tumour retention caused by antigen binding indicates that reduced normal tissue exposure can be obtained with antigen-specific antibodies. The heterogeneous tumour dose distribution observed is, however, a major impediment to the use of alpha-particle emitters against solid tumours. Images Figure 2 Figure 3

Larsen, R. H.; Bruland, O. S.

1998-01-01

348

Supplementation of Alpha 1-Antitrypsin.  

National Technical Information Service (NTIS)

The aim of the study is to explore the feasibility of preparing alpha 1-antitrypsin from the plasma of carefully screened donors who have been found to be free of testable liver abnormalities and eventually supplement patients having inherited alpha 1-ant...

B. H. Bowman G. Powell D. R. Barnett J. C. Gan

1975-01-01

349

Hygroscopic properties of smoke-generated organic aerosol particles emitted in the marine atmosphere  

NASA Astrophysics Data System (ADS)

During the Eastern Pacific Emitted Aerosol Cloud Experiment (E-PEACE), a plume of organic aerosol was produced by a smoke generator and emitted into the marine atmosphere from aboard the R/V Point Sur. In this study, the hygroscopic properties and the chemical composition of the plume were studied at plume ages between 0 and 4 h in different meteorological conditions. In sunny conditions, the plume particles had very low hygroscopic growth factors (GFs): between 1.05 and 1.09 for 30 nm and between 1.02 and 1.1 for 150 nm dry size at a relative humidity (RH) of 92%, contrasted by an average marine background GF of 1.6. New particles were produced in large quantities (several 10 000 cm-3), which lead to substantially increased cloud condensation nuclei (CCN) concentrations at supersaturations between 0.07 and 0.88%. Ratios of oxygen to carbon (O : C) and water-soluble organic mass (WSOM) increased with plume age: from < 0.001 to 0.2, and from 2.42 to 4.96 ?g m-3, respectively, while organic mass fractions decreased slightly (~ 0.97 to ~ 0.94). High-resolution aerosol mass spectrometer (AMS) spectra show that the organic fragment m/z 43 was dominated by C2H3O+ in the small, new particle mode and by C3H7+ in the large particle mode. In the marine background aerosol, GFs for 150 nm particles at 40% RH were found to be enhanced at higher organic mass fractions: an average GF of 1.06 was observed for aerosols with an organic mass fraction of 0.53, and a GF of 1.04 for an organic mass fraction of 0.35.

Wonaschtz, A.; Coggon, M.; Sorooshian, A.; Modini, R.; Frossard, A. A.; Ahlm, L.; Mlmenstdt, J.; Roberts, G. C.; Russell, L. M.; Dey, S.; Brechtel, F. J.; Seinfeld, J. H.

2013-10-01

350

Tables of average distributions of particles emitted by ionized elements (Z = 6--100)  

SciTech Connect

Tables giving the average division of energy between electrons and x-rays emitted by singly ionized elements undergoing bound-bound transitions are provided. The expected number of particles is also given. This data is tabulated by atomic number and subshell of initial vacancy. A description of the method of calculation is also presented. 2 refs., 1 fig., 1 tab.

Lee, P.; Rathkopf, J.; Cullen, D.; Perkins, S.

1990-01-01

351

Evolution of trace gases and particles emitted by a chaparral fire in California  

NASA Astrophysics Data System (ADS)

Biomass burning (BB) is a major global source of trace gases and particles. Accurately representing the production and evolution of these emissions is an important goal for atmospheric chemical transport models. We measured a suite of gases and aerosols emitted from an 81 hectare prescribed fire in chaparral fuels on the central coast of California, US on 17 November 2009. We also measured physical and chemical changes that occurred in the isolated downwind plume in the first ~4 h after emission. The measurements were carried out onboard a Twin Otter aircraft outfitted with an airborne Fourier transform infrared spectrometer (AFTIR), aerosol mass spectrometer (AMS), single particle soot photometer (SP2), nephelometer, LiCor CO2 analyzer, a chemiluminescence ozone instrument, and a wing-mounted meteorological probe. Our measurements included: CO2; CO; NOx; NH3; non-methane organic compounds; organic aerosol (OA); inorganic aerosol (nitrate, ammonium, sulfate, and chloride); aerosol light scattering; refractory black carbon (rBC); and ambient temperature, relative humidity, barometric pressure, and three-dimensional wind velocity. The molar ratio of excess O3 to excess CO in the plume (?O3/?CO) increased from -5.13 (1.13) 10-3 to 10.2 (2.16) 10-2 in ~4.5 h following smoke emission. Excess acetic and formic acid (normalized to excess CO) increased by factors of 1.73 0.43 and 7.34 3.03 (respectively) over the same time since emission. Based on the rapid decay of C2H4 we infer an in-plume average OH concentration of 5.27 (0.97) 106 molec cm-3, consistent with previous studies showing elevated OH concentrations in biomass burning plumes. Ammonium, nitrate, and sulfate all increased over the course of 4 h. The observed ammonium increase was a factor of 3.90 2.93 in about 4 h, but accounted for just ~36% of the gaseous ammonia lost on a molar basis. Some of the gas phase NH3 loss may have been due to condensation on, or formation of, particles below the AMS detection range. NOx was converted to PAN and particle nitrate with PAN production being about two times greater than production of observable nitrate in the first ~4 h following emission. The excess aerosol light scattering in the plume (normalized to excess CO2) increased by a factor of 2.50 0.74 over 4 h. The increase in light scattering was similar to that observed in an earlier study of a biomass burning plume in Mexico where significant secondary formation of OA closely tracked the increase in scattering. In the California plume, however, ?OA/?CO2 decreased sharply for the first hour and then increased slowly with a net decrease of ~20% over 4 h. The fraction of thickly coated rBC particles increased up to ~85% over the 4 h aging period. Decreasing OA accompanied by increased scattering/particle coating in initial aging may be due to a combination of particle coagulation and evaporation processes. Recondensation of species initially evaporated from the particles may have contributed to the subsequent slow rise in OA. We compare our results to observations from other plume aging studies and suggest that differences in environmental factors such as smoke concentration, oxidant concentration, actinic flux, and RH contribute significantly to the variation in plume evolution observations.

Akagi, S. K.; Craven, J. S.; Taylor, J. W.; McMeeking, G. R.; Yokelson, R. J.; Burling, I. R.; Urbanski, S. P.; Wold, C. E.; Seinfeld, J. H.; Coe, H.; Alvarado, M. J.; Weise, D. R.

2012-02-01

352

Evolution of trace gases and particles emitted by a chaparral fire in California  

NASA Astrophysics Data System (ADS)

Biomass burning (BB) is a major global source of trace gases and particles. Accurately representing the production and evolution of these emissions is an important goal for atmospheric chemical transport models. We measured a suite of gases and aerosols emitted from an 81 ha prescribed fire in chaparral fuels on the central coast of California, US on 17 November 2009. We also measured post-emission chemical changes in the isolated downwind plume for ~4 h of smoke aging. The measurements were carried out on board a Twin Otter aircraft outfitted with an airborne Fourier transform infrared spectrometer (AFTIR), aerosol mass spectrometer (AMS), single particle soot photometer (SP2), nephelometer, LiCor CO2 analyzer, a chemiluminescence ozone instrument, and a wing-mounted meteorological probe. Our measurements included: CO2; CO; NOx; NH3; non-methane organic compounds; organic aerosol (OA); inorganic aerosol (nitrate, ammonium, sulfate, and chloride); aerosol light scattering; refractory black carbon (rBC); and ambient temperature, relative humidity, barometric pressure, and three-dimensional wind velocity. The molar ratio of excess O3 to excess CO in the plume (?O3/?CO) increased from -0.005 to 0.102 in 4.5 h. Excess acetic and formic acid (normalized to excess CO) increased by factors of 1.7 0.4 and 7.3 3.0 (respectively) over the same aging period. Based on the rapid decay of C2H4 we infer an in-plume average OH concentration of 5.3 (1.0) 106 molecules cm-3, consistent with previous studies showing elevated OH concentrations in biomass burning plumes. Ammonium, nitrate, and sulfate all increased with plume aging. The observed ammonium increase was a factor of 3.9 2.6 in about 4 h, but accounted for just ~36 % of the gaseous ammonia lost on a molar basis. Some of the gas phase NH3 loss may have been due to condensation on, or formation of, particles below the AMS detection range. NOx was converted to PAN and particle nitrate with PAN production being about two times greater than production of observable nitrate over a 4 h aging period. The excess aerosol light scattering in the plume (normalized to excess CO2) increased by a factor of 2.3 0.7 over 4 h. The increase in light scattering was similar to that observed in an earlier study of a biomass burning plume in Mexico where significant secondary formation of OA closely tracked the increase in scattering. In the California plume, however, ?OA/?CO2 decreased sharply for the first hour and then increased slowly with a net decrease of ~24 % over 4 h. The fraction of thickly coated rBC particles increased almost twofold over the 4 h aging period. Decreasing OA accompanied by increased scattering/coating in the initial aging may be due to a combination of particle coagulation and evaporation processes. Recondensation of species initially evaporated from the particles may have contributed to the subsequent slow rise in OA. We compare our results to observations from other plume aging studies and suggest that differences in environmental factors such as smoke concentration, oxidant concentration, actinic flux, and RH contribute significantly to the variation in plume evolution observations.

Akagi, S. K.; Craven, J. S.; Taylor, J. W.; McMeeking, G. R.; Yokelson, R. J.; Burling, I. R.; Urbanski, S. P.; Wold, C. E.; Seinfeld, J. H.; Coe, H.; Alvarado, M. J.; Weise, D. R.

2011-08-01

353

Quantifying Sulfate, Organics, and Lubrication Oil in Particles Emitted from Military Aircraft Engines.  

National Technical Information Service (NTIS)

1.1 Objectives SERDP Project WP1625 was a multi-component effort to understand volatile contributions to particulate matter (PM) emitted from military aircraft engines. Volatile PM formed when condensable gases emitted in the exhaust form new particles or...

H. Wong J. Peck R. Miake-Lye S. C. Herndon Z. Yu

2012-01-01

354

Characterization and control of airborne particles emitted during production of epoxy/carbon nanotube nanocomposites.  

PubMed

This work characterized airborne particles generated from the weighing of bulk, multiwall carbon nanotubes (CNTs) and the manual sanding of epoxy test samples reinforced with CNTs. It also evaluated the effectiveness of three local exhaust ventilation (LEV) conditions (no LEV, custom fume hood, and biosafety cabinet) for control of particles generated during sanding of CNT-epoxy nanocomposites. Particle number and respirable mass concentrations were measured using an optical particle counter (OPC) and a condensation particle counter (CPC), and particle morphology was assessed by transmission electron microscopy. The ratios of the geometric mean (GM) concentrations measured during the process to that measured in the background (P/B ratios) were used as indices of the impact of the process and the LEVs on observed concentrations. Processing CNT-epoxy nanocomposites materials released respirable size airborne particles (P/B ratio: weighing = 1.79; sanding = 5.90) but generally no nanoparticles (P/B ratio ?1). The particles generated during sanding were predominantly micron sized with protruding CNTs and very different from bulk CNTs that tended to remain in large (>1 ?m) tangled clusters. Respirable mass concentrations in the operator's breathing zone were lower when sanding was performed in the biological safety cabinet (GM = 0.20 ?g/m(3) compared with those with no LEV (GM = 2.68 ?g/m(3) or those when sanding was performed inside the fume hood (GM = 21.4 ?g/m(3); p-value < 0.0001). The poor performance of the custom fume hood used in this study may have been exacerbated by its lack of a front sash and rear baffles and its low face velocity (0.39 m/sec). PMID:21253981

Cena, Lorenzo G; Peters, Thomas M

2011-02-01

355

Identification of platinum and palladium particles emitted from vehicles and dispersed into the surface environment.  

PubMed

Platinum, palladium, and rhodium are emitted from vehicle catalytic converters. Until now, the form of precious metal particles in road dust and urban waste has not been identified. This study has located, imaged, and analyzed these particles in road dust and gully waste. Two fragments of catalytic converter have been observed in road dust. They are 40-80 ?m in size and covered in many minute particles (<0.3 ?m) of either platinum with minor rhodium or palladium. One fragment identified in gully sediment is smaller, 25 ?m in diameter, hosting only one attached particle of palladium with minor rhodium. As fragments are washed off roads they begin to disintegrate and the precious metals become detached. Also precious metal-bearing particles have been located in incinerated sewage ash including a 20 ?m diameter cluster of <3 ?m sized platinum particles that may be the remains of a catalytic converter fragment that has survived incineration. The form of these precious metal-bearing particles described here reveals that as they are dispersed from roads they are likely to be present predominantly as two particle sizes. Either they are attached to larger fragments of catalytic converter or they are released as individual detached tiny <0.3 ?m to nanoparticle sizes. PMID:22313190

Prichard, Hazel M; Fisher, Peter C

2012-03-07

356

A Model to Predict the Breathing Zone Concentrations of Particles Emitted from Surfaces  

EPA Science Inventory

Activity based sampling (ABS) is typically performed to assess inhalation exposure to particulate contaminants known to have low, heterogeneous concentrations on a surface. Activity based sampling determines the contaminant concentration in a person's breathing zone as they perfo...

357

Particles emitted from indoor combustion sources: size distribution measurement and chemical analysis.  

PubMed

This study is primarily focused toward measuring the particle size distribution and chemical analysis of particulate matter that originates from combustion sources typically found in Indian urban homes. Four such sources were selected: cigarette, incense stick, mosquito coil, and dhoop, the latter being actually a thick form of incense stick. Altogether, seven of the most popular brands available in the Indian market were tested. Particle size distribution in the smoke was measured using a scanning mobility particle sizer, using both long and nano forms of differential mobility analyzer (DMA), with readings averaged from four to six runs. The measurable particle size range of the nano DMA was 4.6 nm to 157.8 nm, whereas that of the long DMA was 15.7 nm to 637.8 nm. Therefore, readings obtained from the long and the nano DMA were compared for different brands as well as for different sources. An overlap was seen in the readings in the common range of measurement. The lowest value of peak concentration was seen for one brand of incense stick (0.9 x 10(6) cm(-3)), whereas the highest (7.1 x 10(6) cm(-3)) was seen for the dhoop. Generally, these sources showed a peak between 140 and 170 nm; however, 2 incense stick brands showed peaks at 79 nm and 89 nm. The dhoop showed results much different from the rest of the sources, with a mode at around 240 nm. Chemical analysis in terms of three heavy metals (cadmium, zinc, and lead) was performed using graphite tube atomizer and flame-atomic absorption spectrophotometer. Calculations were made to assess the expected cancer and noncancer risks, using published toxicity potentials for these three heavy metals. Our calculations revealed that all the sources showed lead concentrations much below the American Conference of Governmental Industrial Hygienists (ACGIH) threshold limit value (TLV) level. One of the two mosquito coil brands (M(2)) showed cadmium concentrations two times higher than the California Environmental Protection Agency (Cal EPA) reference exposure level (REL). The latter also showed the highest carcinogenic risks of 350 people per million population. The amount of zinc obtained from the sources, however, was found to be quite below the standard limits, implying no risk in terms of zinc. PMID:19591538

Roy, A A; Baxla, S P; Gupta, Tarun; Bandyopadhyaya, R; Tripathi, S N

2009-08-01

358

Investigation of the airborne submicrometer particles emitted by dredging vessels using a plume capture method  

NASA Astrophysics Data System (ADS)

A method for investigating ship emissions, known as the plume capture and analysis system (PCAS) is described. The PCAS is applied to the task of measuring airborne pollutant emission factors (EFs) and particle size distributions aboard two dredgers, although the technique is also suitable for remote measurements. EFs were measured relative to the fuel consumption using the fuel combustion derived plume CO2. Each measurement typically took 6min to complete and during one day, 4050 measurements were possible. EFs for particle number (PN), NOx, SO2, and PM2.5 were independent within a targeted dilution factor range of 501000 suitable for onboard and remote sampling.For the Amity, the EF ranges were PN: 2.29.6נ1015(kg-fuel)?1; NOx: 3572g(NO2)(kg-fuel)?1, SO2 0.61.1g(SO2)(kg-fuel)?1and PM2.5: 0.76.1g(PM2.5)(kg-fuel)?1. For the Brisbane they were PN: 1.01.5נ1016(kg-fuel)?1, NOx: 3.48.0g(NO2)(kg-fuel)?1, SO2: 1.31.7g(SO2)(kg-fuel)?1 and PM2.5: 1.25.6g(PM2.5)(kg-fuel)?1.Particle number emission factors as a function of size as well as the count median diameter (CMD), and geometric standard deviation of the size distributions are provided. This size distributions were consistently uni-modal in the range below 500nm for both vessels, and this CMD always lay within the accumulation mode range.

Juwono, Alamsyah M.; Johnson, G. R.; Mazaheri, M.; Morawska, L.; Roux, F.; Kitchen, B.

2013-07-01

359

Ionization of the Atmosphere Due to Beta Particles Emitted by Fission Products  

Microsoft Academic Search

Persistent ionization of air at moderate heights, just below the E ; layer, after high-altitude nuclear detonations is predominantly due to radiations ; accompanying radioactive decay of fission products. The most important are BETA ; particles, which are restricted in their movements by the earth's magnetic field ; and thus create ionized clouds of high density in localized regions. A

S. Kownacki

1963-01-01

360

Evolution of trace gases and particles emitted by a chaparral fire in California  

Microsoft Academic Search

Biomass burning (BB) is a major global source of trace gases and particles. Accurately representing the production and evolution of these emissions is an important goal for atmospheric chemical transport models. We measured a suite of gases and aerosols emitted from an 81 ha prescribed fire in chaparral fuels on the central coast of California, US on 17 November 2009.

S. K. Akagi; J. S. Craven; J. W. Taylor; G. R. McMeeking; R. J. Yokelson; I. R. Burling; S. P. Urbanski; C. E. Wold; J. H. Seinfeld; H. Coe; M. J. Alvarado; D. R. Weise

2011-01-01

361

TOF-SIMS measurements of the exhaust particles emitted from gasoline and diesel engine vehicles  

Microsoft Academic Search

We obtained the detailed compositional information of diesel and gasoline exhaust particles, and discussed the possibility of the classification into each emission source. The intensities of Ca+ and hydrocarbons were relatively high in the TOF-SIMS spectrum of the gasoline exhaust particles. The secondary ions such as NH4+ and Si(CH3)3+ were strongly detected from the diesel exhaust particles. From TOF-SIMS images

B. Tomiyasu; M. Owari; Y. Nihei

2006-01-01

362

TOF-SIMS measurements of the exhaust particles emitted from gasoline and diesel engine vehicles  

NASA Astrophysics Data System (ADS)

We obtained the detailed compositional information of diesel and gasoline exhaust particles, and discussed the possibility of the classification into each emission source. The intensities of Ca + and hydrocarbons were relatively high in the TOF-SIMS spectrum of the gasoline exhaust particles. The secondary ions such as NH 4+ and Si(CH 3) 3+ were strongly detected from the diesel exhaust particles. From TOF-SIMS images of each type of exhaust particles, Ca + of the gasoline exhaust particles and Si(CH 3) 3+ of diesel exhaust particles were strongly detected from the large particles with diameter of 0.3 ?m. From these results, the exhaust particles collected in the atmosphere near the traffic route can be classified by their origin by using TOF-SIMS information.

Tomiyasu, B.; Owari, M.; Nihei, Y.

2006-07-01

363

METHODS FOR ANALYZING INORGANIC COMPOUNDS IN PARTICLES EMITTED FROM STATIONARY SOURCES  

EPA Science Inventory

The research described was initiated with the objective of developing methods to identify and measure inorganic compounds in particulate emissions which emanate from sources using or processing fossil fuels. An extensive literature review was carried out to ascertain prior knowle...

364

Toxicity of particles emitted from combustion of waste crankcase oil: in vitro and in vivo studies  

SciTech Connect

The ever-rising cost of energy provides incentives for the utilization of low-cost waste crankcase oil (WCO) for space heating. Although WCO is known to contain toxic heavy metals, the potential health hazards of emissions and waste products resulting from the combustion of WCO are unknown. Thus, the toxicity of the emission particles and waste products from two different types of burners, a Dravo atomizing oil burner (AOB) and a Kroll vaporizing oil burner (VOB), is evaluated using automotive WCO. Samples are characterized by performing elemental analysis and scanning electron microscopy. Both burners emitted fine (less than or equal to 3 microns), respirable particles. The AOB emission particles contained high concentrations of toxic heavy metals, especially Pb, which showed concentrations as high as 7.5%. The VOB retained a significant amount of heavy metals in the burner residue and emitted a much smaller quantity into the air. The toxicity of AOB emission particles, VOB emission particles, and VOB waste residue is evaluated in three bioassay systems, including a rabbit alveolar macrophage (RAM) cytotoxicity in vitro assay, an intratracheal injection infectivity assay, and a peritoneal irritancy test in mice. The emission particles from both burners and leachate from VOB residue produce a dose-related reduction in viability and cellular adenosine triphosphate (ATP) in alveolar macrophages following 20-hr exposure. Acidity of the RAM medium due to the presence of VOB emission particles and waste leachate contributes to its toxicity.

Mumford, J.L.; Hatch, G.E.; Hall, R.E.; Jackson, M.A.; Merrill, R.G. Jr.; Lewtas, J.

1986-07-01

365

Alpha-trifluoromethylated carbanion synthons.  

PubMed

Trifluomethylated organic compounds often have properties that make them suitable for diverse applications, including materials science, agrochemistry, and pharmaceutical industry. But of all the therapeutic drugs currently available, about 10% of them have a partially fluorinated moiety. Thus, a great deal of attention is being paid to the development of reliable methodologies for trifluoromethylation. Introduction of a trifluoromethyl group into the target molecules mostly relies on either trifluoromethylating reagents or trifluoromethylated synthetic blocks. The chemistry of trifluoromethyl carbanions, nucleophilic trifluoromethylating agents such as the Ruppert-Prakash reagent, and organometallic species has been intensively developed for their important synthetic applications. But the chemistry of beta,beta,beta-trifluoroethyl carbanions (alpha-trifluoromethyl carbanions) and organometallic species has remained undeveloped despite their potential usefulness in organic synthesis. The issue needs to be addressed. This Account outlines successful alkylations and useful synthetic applications of alpha-trifluoromethyl carbanions, such as alpha-substituted beta,beta,beta-trifluoroethyl, alpha-trifluoromethylethenyl, trifluoroacetimidoyl, alpha-trifluoromethyloxiranyl, and related alpha-trifluoromethylated carbanions. The strong electron-withdrawing effect of the alpha-trifluoromethyl group may stabilize the carbanion species electronically. But alpha-trifluoromethyl carbanions and their corresponding organometallic species mostly release fluoride spontaneously to produce difluoroalkenes. This notorious decomposition of alpha-trifluoromethylated carbanions and anionoids has hindered the development of these species for organic synthesis. A well-designed device for the generation, stabilization, and acceleration for alkylation of the alpha-trifluoromethylated carbanions is needed for their synthetic application, as well as stabilization by the electron-withdrawing alpha-substituent. The reported alpha-substituted alpha-trifluoromethyl carbanions can be roughly categorized into three classes based on their structures. The first category, A, is pi-conjugation-stabilized carbanions, which are stabilized by ester, nitro, sulfone, carbonyl, or phenyl groups. alpha-Substituents of these carbanions can delocalize the negative charges on their pi-system with large sigma R electron-withdrawing effects; this prevents accumulation of negative charge on the fluorine atoms. The second category, B, consists of carbanions with sp(3) orbitals either of highly halogenated carbanionsexamples include pentafluoroethyl(trimethyl)fluorosilicate, pentafluoroethyllithium, and alpha,alpha-dichloro-beta,beta,beta-trifluoroethylzinc speciesor of cyclic structures such as oxiranyl- and aziridinyllithiums. Both of these carbanions are also stabilized since they reduce molecular orbital (MO) overlapping of the carbanion orbital to C-F bond orbitals. The third category, C, has carbanions with their anion center at the sp(2) orbital, such as alpha-trifluoromethylated alkenyl carbanions and imidoyl carbanions. These sp(2) orbitals of the carbanion center usually have a small overlap with the C-F bonds of trifluoromethyl groups. The small overlap is able to suppress the E2-type eliminations. alpha-Trifluoromethylated carbanions are, in general, unstable. Their stability is largely affected by factors like hybridization of the orbital that accommodates lone pair electrons, the electronic nature of the alpha-substituents, the degree of covalency in a bond between the carbon and metal, the class of countercation, stabilization by chelation of a metal cation, and so on. The stability, therefore, can be sometimes controlled by tuning these factors adequately so that they can be used for organic synthesis. The chemistry of alpha-trifluoromethylated carbanions for organic synthesis has been progressing steadily. However, the simplest trifluoroethyl and trifluoroacetyl carbanions have never been successfully produced and employed for organic synthesis. Elegant gene

Uneyama, Kenji; Katagiri, Toshimasa; Amii, Hideki

2008-06-14

366

Rapid identification and analysis of airborne plutonium using a combination of alpha spectroscopy and inductively coupled plasma mass spectrometry.  

PubMed

Recent wildland fires near two U.S. nuclear facilities point to a need to rapidly identify the presence of airborne plutonium during incidents involving the potential release of radioactive materials. Laboratory turn-around times also need to be shortened for critical samples collected in the earliest stages of radiological emergencies. This note discusses preliminary investigations designed to address both these problems. The methods under review are same day high-resolution alpha spectroscopy to screen air filter samples for the presence of plutonium and inductively coupled plasma mass spectrometry to perform sensitive plutonium analyses. Thus far, using modified alpha spectroscopy techniques, it has been possible to reliably identify the approximately 5.2 MeV emission of 239Pu on surrogate samples (air filters artificially spiked with plutonium after collection) even though the primary alpha-particle emissions of plutonium are, as expected, superimposed against a natural alpha radiation background dominated by short-lived radon and thoron progeny (approximately 6-9 MeV). Several processing methods were tested to prepare samples for analysis and shorten laboratory turn-around time. The most promising technique was acid-leaching of air filter samples using a commercial open-vessel microwave digestion system. Samples prepared in this way were analyzed by both alpha spectroscopy (as a thin-layer iron hydroxide co-precipitate) and inductively coupled plasma mass spectrometry. The detection levels achieved for 239Pu--approximately 1 mBq m(-3) for alpha spectroscopy screening, and, < 0.1 mBq m(-3) for inductively coupled plasma mass spectrometry analysis--are consistent with derived emergency response levels based on EPA's Protective Action Guides, and samples can be evaluated in 36 to 72 h. Further, if samples can be returned to a fixed-laboratory and processed immediately, results from mass spectrometry could be available in as little as 24 h. When fully implemented, these techniques have the potential to provide useful information and improved operational flexibility to emergency planners and first-responders during radiological emergencies. PMID:13678286

Farmer, Dennis E; Steed, Amber C; Sobus, Jon; Stetzenbach, Klaus; Lindley, Kaz; Hodge, Vernon F

2003-10-01

367

Triplicated alpha-globin loci in humans.  

PubMed

We have identified 12 individuals who are heterozygous for a chromosome with three alpha-globin genes. We determined the presence of the third alpha-globin locus by restriction endonuclease digestion and hybridization with alpha-globin cDNA probes. The three alpha-globin loci resided in an elongated fragment on digestion with EcoRI, BamHI, and Xba I, and the third locus was present in an additional 3.7-kilobase fragment on digestion with Hpa I, Sac I, and Bgl II. The locations of the restriction sites are compatible with a nonhomologous crossover mechanism producing the triple alpha loci. The frequency of the triple alpha loci was 0.0036 in American blacks and less than 0.004 in Sardinians, but was higher in Greek Crypriots (0.05). Individuals with five alpha-globin genes (alpha alpha/alpha alpha alpha) apparently showed no clinical or hematologic abnormalities. PMID:6928643

Goossens, M; Dozy, A M; Embury, S H; Zachariades, Z; Hadjiminas, M G; Stamatoyannopoulos, G; Kan, Y W

1980-01-01

368

Radiative corrections to the muonium hyperfine structure. II. The {alpha}(Z{alpha}){sup 2} correction  

SciTech Connect

This is the second of a series of papers on the radiative corrections of order {alpha}{sup 2}(Z{alpha}), {alpha}(Z{alpha}){sup 2}, and various logarithmic terms of order {alpha}{sup 4}, to the hyperfine structure of the muonium ground state. This paper deals with the {alpha}(Z{alpha}){sup 2} correction. Based on the NRQED bound state theory, we isolated the term of order {alpha}(Z{alpha}){sup 2} exactly. Our result +16.9042(11){alpha}(Z{alpha}){sup 2}E{sub F}/{pi} for the non-logarithmic part is consistent with the {alpha}(Z{alpha}){sup 2} part of Sapirstein{close_quote}s calculation and the recent result of Pachucki, and reduces the numerical uncertainty in the {alpha}(Z{alpha}){sup 2} term by 2 orders of magnitude. {copyright} {ital 1997} {ital The American Physical Society}

Nio, M. [Graduate School of Human Culture, Nara Womens University, Nara 630 (Japan); Kinoshita, T. [Newman Laboratory of Nuclear Studies, Cornell University, Ithaca, New York 14853 (United States)

1997-06-01

369

Reversible adrenergic alpha-receptor blocking action of 2,4'-dimethyl-3-piperidino-propiophenone (tolperisone).  

PubMed

The vascular action of 2,4'-dimethyl-3-piperidino-propiophenone hydrochloride (tolperisone hydrochloride), a centrally acting muscle relaxant, was investigated in pentobarbital anesthetized dogs. Tolperisone given intravenously produced a transient hypotension, tachycardia, and hyperventilation. The drug increased the femoral arterial flow, and decreased the superior mesenteric arterial flow following an initial transient increase. When injected directly into femoral and mesenteric arteries, tolperisone caused a rapid increase in both arterial flow (vasodilatation). However, femoral vessels were about 90 times as sensitive as mesenteric vessels to tolperisone. These results indicate that tolperisone shifts the blood volume from mesenteric (visceral) vessels to femoral (skeltal) ones. The femoral vasodilatation produced by i.a. tolperisone was not depressed by the pretreatment with i.a. propranolol, atropine or chlorphenylamine. Tolperisone decreased the contractile force in an isolated and cross-circulated papillary muscle. Tolperisone produced adrenaline reversal and antagonized the pressor response to noradrenaline. Moreover, femoral vasoconstriction caused by i.a. adrenaline was converted to vasodilatation and that caused by i.a. noradrenaline was depressed during an i.a. infusion of tolperisone. These results indicate that tolperisone blocks adrenergic alpha-receptors. The blocking action was rapid in onset, short-lived, and in addition, competitive. PMID:12392

Furuta, Y; Yoshikawa, A

1976-10-01

370

Alpha 1 -antitrypsin and alpha 2 -macroglobulin in newborn infants  

Microsoft Academic Search

The following tests were performed within the first week of life in 129 newborn infants: determination of alpha1-antitrypsin, alpha2-macroglobulin, antithrombin III, fibrinogen, prothrombin, accelerin, convertin and plasminogen. The newborns were divided into three groups: group (a), healthy newborns with a normal obstetric history (n=62); group (b), newborns without clinical signs of illness, but a complicated obstetric history (n=49); group (c),

U. Gbel; A. Triebel; C. Petrich; H. Voss

1978-01-01

371

A Ly{alpha} EMITTER WITH AN EXTREMELY LARGE REST-FRAME EQUIVALENT WIDTH OF {approx}900 A AT z = 6.5: A CANDIDATE POPULATION III-DOMINATED GALAXY?  

SciTech Connect

We have identified a very interesting Ly{alpha} emitter (LAE), whose Ly{alpha} emission line has an extremely large observed equivalent width of EW{sub 0} = 436{sup +422}{sub -{sub 149}} A, which corresponds to an extraordinarily large intrinsic rest-frame equivalent width of EW{sup int}{sub 0} = 872{sup +844}{sub -{sub 298}} A after the average intergalactic absorption correction. The object was spectroscopically confirmed to be a real LAE by its apparent asymmetric Ly{alpha} line profile detected at z = 6.538. The continuum emission of the object was definitely detected in our deep z'-band image; thus, its EW{sub 0} was reliably determined. Follow-up deep near-infrared spectroscopy revealed emission lines of neither He II {lambda}1640 as an apparent signature of Population III (Pop III) nor C IV {lambda}1549 as proof of an active nucleus. No detection of the short-lived He II {lambda}1640 line is not necessarily inconsistent with the interpretation that the underlying stellar population of the object is dominated by Pop III. We found that the observed extremely large EW{sub 0} of the Ly{alpha} emission and the upper limit on the EW{sub 0} of the He II {lambda}1640 emission can be explained by population synthesis models favoring a very young age less than 2-4 Myr and massive metal-poor (Z < 10{sup -5}) or even metal-free stars. The observed large EW{sub 0} of Ly{alpha} is insufficiently explained by Population I/II synthesis models with Z {>=} 10{sup -3}. However, we cannot conclusively rule out the possibility that this object is composed of a normal stellar population with a clumpy dust distribution, which could enhance the Ly{alpha} EW{sub 0}, though its significance is still unclear.

Kashikawa, Nobunari; Hayashi, Masao; Iye, Masanori [Optical and Infrared Astronomy Division, National Astronomical Observatory, Mitaka, Tokyo 181-8588 (Japan); Nagao, Tohru; Ota, Kazuaki [Department of Astronomy, Graduate School of Science, Kyoto University, Kyoto 606-8502 (Japan); Toshikawa, Jun; Ishizaki, Yoshifumi; Shibuya, Takatoshi [Department of Astronomy, School of Science, Graduate University for Advanced Studies, Mitaka, Tokyo 181-8588 (Japan); Egami, Eiichi; Jiang, Linhua [Steward Observatory, University of Arizona, 933 North Cherry Avenue, Tucson, AZ 85721 (United States); Ly, Chun [Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States); Malkan, Matthew A. [Department of Physics and Astronomy, University of California, Los Angeles, CA 90095-1547 (United States); Matsuda, Yuichi [Radio Astronomy Division, National Astronomical Observatory, Mitaka, Tokyo 181-8588 (Japan); Shimasaku, Kazuhiro [Department of Astronomy, University of Tokyo, Hongo, Tokyo 113-0033 (Japan); Taniguchi, Yoshiaki; Shioya, Yasuhiro, E-mail: n.kashikawa@nao.ac.jp [Research Center for Space and Cosmic Evolution, Ehime University, Bunkyo-cho, Matsuyama 790-8577 (Japan)

2012-12-20

372

5-Alpha Reductase Inhibitor Information  

Center for Drug Evaluation (CDER)

... FDA Drug Safety Communication: 5-alpha reductase inhibitors (5-ARIs) may increase the risk of a more serious form of prostate cancer 6/9/2011; ... More results from www.fda.gov/drugs/drugsafety/informationbydrugclass

373

Synthesis and herbicidal activity of novel alpha,alpha,alpha-trifluoro-m-tolyl pyridazinone derivatives.  

PubMed

A series of novel alpha,alpha,alpha-trifluoro-m-tolyl pyridazinone derivatives was synthesised. Herbicidal activities of the two intermediate compounds and 15 pyridazinone derivatives were evaluated through barnyardgrass and rape cup tests and Spirodela polyrrhiza (L.) Schleiden tests. Selected compounds were also evaluated under greenhouse conditions. Bleaching activities were observed at 10 microg ml(-1) and some compounds exhibited herbicidal activities at a rate of 300 g ha(-1). The relationship between crystal structures and herbicidal activities is discussed through a comparison of two compounds (5a and 5f). PMID:16602079

Xu, Han; Zou, Xiao-Mao; Zhu, You-Quan; Liu, Bin; Tao, Han-Lin; Hu, Xu-Hong; Song, Hai-Bin; Hu, Fang-Zhong; Wang, Yong; Yang, Hua-Zheng

2006-06-01

374

Warm {alpha}-nucleon matter  

SciTech Connect

The properties of warm dilute {alpha}-nucleon matter are studied in a variational approach in the Thomas-Fermi approximation starting from an effective two-body nucleon-nucleon interaction. The equation of state, symmetry energy, incompressibility of the said matter, and {alpha} fraction are in consonance with those evaluated from the virial approach, which sets the benchmark for such calculations at low densities.

Samaddar, S. K.; De, J. N. [Saha Institute of Nuclear Physics, 1/AF Bidhannagar, Kolkata 700064 (India)

2011-05-15

375

Alpha 1-adrenergic receptor structure  

Microsoft Academic Search

The structure of the alpha 1-adrenergic receptor was investigated by comparing polypeptides identified by sodium dodecyl sulfate (NaDodSO4)-polyacrylamide gel electrophoresis with the size of the intact receptor in cell membranes as determined by target size analysis. The alpha 1-adrenergic receptor from rat liver membranes affinity-labeled with (³H)phenoxybenzamine, a covalent affinity reagent, appeared as a single polypeptide with a molecular mass

J. C. Venter; P. Horne; B. Eddy; R. Greguski; C. M. Fraser

1984-01-01

376

Determination of alpha preformation for heavy nuclei  

Microsoft Academic Search

The alpha preformation factor and the penetration probability have been analyzed for heavy even-even nuclei in the frame of double folding model using the experimental released energies and alpha decay half-lives. The alpha preformation factors are compared with Po, Rn, Ra isotopes as well as Cm, Cf, Fm, No, Rf isotopes, respectively. It is shown that the alpha preformation factor

G. L. Zhang; X. Y. Le; H. Q. Zhang

2009-01-01

377

Modulation of gene expression by alpha-tocopherol and alpha-tocopheryl phosphate  

Technology Transfer Automated Retrieval System (TEKTRAN)

The naturally occurring vitamin E analogue, alpha-tocopheryl phosphate (alphaTP), has been reported to be more potent in reducing cell proliferation and the expression of the CD36 scavenger receptor than the un-phosphorylated alpha-tocopherol (alpha T). We have now assessed the effects of alpha T an...

378

Mechanism of alpha-tocopheryl-phosphate (alpha-TP) transport across the cell membrane  

Technology Transfer Automated Retrieval System (TEKTRAN)

We have reported that alpha-TP is synthesized and hydrolyzed in animal cells and tissues; it modulates also several cell functions (FRBM 39:970, and UBMB Life, 57:23, 2005). While it is similar to alpha-tocopherol (alpha-T), alpha-TP appears to be more potent than alpha-T in inhibiting cell prolifer...

379

Workshop on Precision Measurements of $\\alpha_s$  

SciTech Connect

These are the proceedings of the Workshop on Precision Measurements of {alpha}{sub s} held at the Max-Planck-Institute for Physics, Munich, February 9-11, 2011. The workshop explored in depth the determination of {alpha}{sub s}(m{sub Z}) in the {ovr MS} scheme from the key categories where high precision measurements are currently being made, including DIS and global PDF fits, {tau}-decays, electro-weak precision observables and Z-decays, event-shapes, and lattice QCD. These proceedings contain a short summary contribution from the speakers, as well as the lists of authors, conveners, participants, and talks.

Bethke, Siegfried; /Munich, Max Planck Inst.; Hoang, Andre H.; /Vienna U.; Kluth, Stefan; /Munich, Max Planck Inst.; Schieck, Jochen; /Munich U.; Stewart, Iain W.; Aoki, S.; Beneke, M.; Bethke, S.; Blumlein, J.; Brambilla, N.; Brodsky, S.; /MIT, LNS

2011-10-01

380

Nonlocal potential form for s-wave (alpha)-(alpha) scattering.  

National Technical Information Service (NTIS)

Low energy s-wave (alpha)-(alpha) phase shifts that agree well with the measured set, have been extracted using a nonlocal interaction formed by folding (local real) nucleon -(alpha) particle interactions with density matrix elements of the (projectile) (...

K. Amos M. T. Bennett

1997-01-01

381

Binding of anhydrotrypsin to alpha 2-macroglobulin.  

PubMed Central

Radiolabelled anhydrotrypsin was bound by alpha 2M (alpha 2-macroglobulin) sufficiently tightly to resist separation during gel electrophoresis; 2 mol of anhydrotrypsin were bound/mol of alpha 2M, but the interaction differed in important respects from that between active proteinases and alpha 2M. Anhydrotrypsin was bound by the electrophoretically 'fast' form of alpha 2M, although much less effectively than by the 'slow' form. The inactive enzyme was displaced from alpha 2M by trypsin inhibitor, the order of effectiveness being aprotinin > soya-bean trypsin inhibitor > benzamidine. Saturation of alpha 2M with anhydrotrypsin did not prevent subsequent binding and inhibition of active trypsin by the alpha 2M, and the anhydrotrypsin was not displaced during this reaction. Anhydrotrypsin bound by alpha 2M retained its ability to react with antibodies against trypsin, whereas bound trypsin did not. Images Fig. 1. Fig. 2.

Sayers, C A; Barrett, A J

1980-01-01

382

Bremsstrahlung in {alpha} Decay Reexamined  

SciTech Connect

A high-statistics measurement of bremsstrahlung emitted in the {alpha} decay of {sup 210}Po has been performed, which allows us to follow the photon spectra up to energies of {approx}500 keV. The measured differential emission probability is in good agreement with our theoretical results obtained within the quasiclassical approximation as well as with the exact quantum mechanical calculation. It is shown that, due to the small effective electric dipole charge of the radiating system, a significant interference between the electric dipole and quadrupole contributions occurs, which is altering substantially the angular correlation between the {alpha} particle and the emitted photon.

Boie, H.; Scheit, H.; Jentschura, U. D.; Koeck, F.; Lauer, M.; Schwalm, D. [Max-Planck-Institut fuer Kernphysik, D-69117 Heidelberg (Germany); Milstein, A. I.; Terekhov, I. S. [Budker Institute of Nuclear Physics, 630090 Novosibirsk (Russian Federation)

2007-07-13

383

Test chamber for alpha spectrometry  

DOEpatents

Alpha emitters for low-level radiochemical analysis by measurement of alpha spectra are positioned precisely with respect to the location of a surface-barrier detector by means of a chamber having a removable threaded planchet holder. A pedestal on the planchet holder holds a specimen in fixed engagement close to the detector. Insertion of the planchet holder establishes an O-ring seal that permits the chamber to be pumped to a desired vacuum. The detector is protected against accidental contact and resulting damage.

Larsen, Robert P. (Downers Grove, IL)

1977-01-01

384

[Radioprotective effect of alpha 2- adrenoreceptor agonists].  

PubMed

It is confirmed in experiments with selective antagonists, that radioprotective effects (RPE) of phenylephrine is realised by means of alpha 1--and RPE of clonidine--by means of alpha 2-adrenoceptors (AR). Guanobenz, more selective alpha 2-agonist with another structure, has high RPE too. Chemical analogues of clonidine (alpha-antagonist phentolamine, L-DOPA, DOP-serine), which don't cause selective stimulation of alpha 2-AR, don't protect mice. alpha 2-Agonists are new effective group of radioprotectors. PMID:7904881

Kulinski?, V I; Kovtun, V Iu; Klimova, A D; Iashunski?, V G

385

Order alpha^2 corrections to the decay rate of parapositronium  

Microsoft Academic Search

Parapositronium, the spin-0 electron-positron bound state, decays electromagnetically to an even number of photons. The theoretical expression for its decay rate has the form Gamma_p-Ps = Gamma0 Bigl [ 1 + A alpha \\\\over pi - 2 alpha^2 ln alpha + B Bigl ( alpha \\\\over pi Bigr )^2 - 3 alpha^3 \\\\over 2 pi ln^2 alpha + C alpha^3

Gregory Adkins; Richard Fell; Nathan McGovern; Jonathan Sapirstein

2003-01-01

386

Alpha Testing Escape from Diab  

Technology Transfer Automated Retrieval System (TEKTRAN)

Alpha testing was conducted of sessions 2 and 3 from Diab to assess whether the activities worked as expected, and whether children in the target ages enjoyed it. Data include both RA observations of child performance while playing the games and cognitive interview responses from the players after t...

387

Alpha Sources Deposit by Sublimation.  

National Technical Information Service (NTIS)

We studied and realized a device able to perform some very thin deposition used for alpha spectrometry measurements. Sources are prepared by sublimation of the sample in a vacuum container. The energy required for this sublimation is furnished by a laser ...

F. Amoudry J. F. Eloy

1983-01-01

388

Alpha Proton X ray Spectrometer.  

National Technical Information Service (NTIS)

Mars Pathfinder will carry an alpha-proton x ray spectrometer (APX) for the determination of the elemental chemical composition of Martian rocks and soils. The instrument will measure the concentration of all major and some minor elements, including C, N,...

R. Rieder H. Waeke T. Economou

1994-01-01

389

Alcoholism, Alpha Production, and Biofeedback  

ERIC Educational Resources Information Center

|Electroencephalograms of 20 alcoholics and 20 nonalcoholics were obtained. Data indicated that alcoholics produced less alpha than nonalcoholics. In one training condition subjects were given accurate biofeedback, whereas in the other condition subjects were given random (noncontingent) feedback. Accurate biofeedback did not result in greater

Jones, Frances W.; Holmes, David S.

1976-01-01

390

ISS Update: Alpha Magnetic Spectrometer  

NASA Video Gallery

NASA Public Affairs Officer Kelly Humphries interviews Trent Martin, Johnson Space Center project manager for the Alpha Magnetic Spectrometer (AMS) aboard the International Space Station. Questions? Ask us on Twitter @NASA_Johnson and include the hashtag #askStation. For the latest news about the space station, visit http://www.nasa.gov/station.

Gerald T Wright

2012-02-24

391

Alpha proton x ray spectrometer  

NASA Astrophysics Data System (ADS)

Mars Pathfinder will carry an alpha-proton x ray spectrometer (APX) for the determination of the elemental chemical composition of Martian rocks and soils. The instrument will measure the concentration of all major and some minor elements, including C, N, and O at levels above typically 1 percent.

Rieder, Rudi; Waeke, H.; Economou, T.

392

Alpha 1-adrenergic receptor structure  

SciTech Connect

The structure of the alpha 1-adrenergic receptor was investigated by comparing polypeptides identified by sodium dodecyl sulfate (NaDodSO4)-polyacrylamide gel electrophoresis with the size of the intact receptor in cell membranes as determined by target size analysis. The alpha 1-adrenergic receptor from rat liver membranes affinity-labeled with (/sup 3/H)phenoxybenzamine, a covalent affinity reagent, appeared as a single polypeptide with a molecular mass of 85,000 daltons (Da) on NaDodSO4-polyacrylamide gels. In the absence of protease inhibitors, smaller peptides of 58-62 kDa and 40-45 kDa, specifically labeled with (/sup 3/H)phenoxybenzamine, were also apparent on NaDodSO4 gels. In order to determine whether the 85-kDa protein represented all or only a portion of the alpha 1-receptor, radiation inactivation (target size analysis) was undertaken. Radiation-induced receptor inactivation was measured by the loss of specific (/sup 3/H)phenoxybenzamine and (/sup 3/H)prazosin binding and by the loss of affinity-labeled alpha 1-adrenergic receptors on NaDodSO4 gels. Target size analysis of rat liver alpha 1-receptors indicated that the intact membrane-bound receptor has an average molecular mass of 160,000 Da. These data suggest that the intact alpha-receptor may exist in the membrane as a dimer of two 85,000-Da subunits. The structure of the alpha 1-receptor was further studied by limited proteolysis of the 85-kDa protein isolated from NaDodSO4 gels. Trypsin, chymotrypsin, and papain produce smaller peptides similar to those produced during membrane isolation in the absence of protease inhibition. Limited proteolysis of the membrane-bound receptor produces water-soluble peptides, the largest of which is 45,000 Da. This peptide contains the ligand-binding domain and protrudes from the membrane into the extracellular space.

Venter, J.C.; Horne, P.; Eddy, B.; Greguski, R.; Fraser, C.M.

1984-09-01

393

Modulation of gene expression by alpha-tocopherol and alpha-tocopheryl phosphate in thp-1 monocytes  

Technology Transfer Automated Retrieval System (TEKTRAN)

The naturally occurring vitamin E analogue, alpha-tocopheryl phosphate (alphaTP), has been reported to be more potent than the un-phosphorylated alpha alpha-tocopherol (alphaT). We have now measured plasma levels of alphaTP and compared the cellular effects of alphaTP and gamma-tocopheryl phosphate ...

394

A synopsis of collective alpha effects and implications for ITER  

SciTech Connect

This paper discusses the following: Alpha Interaction with Toroidal Alfven Eigenmodes; Alpha Interaction with Ballooning Modes; Alpha Interaction with Fishbone Oscillations; and Implications for ITER.

Sigmar, D.J.

1990-10-01

395

Coincidence of EEG alpha Patterns in Humans.  

National Technical Information Service (NTIS)

The appearance of alpha patterns in one human may influence its appearance in another human. In selected instances, the coincidence of alpha patterns appear simultaneously in the EEG to a highly significant greater degree than would be expected by random ...

T. Behrendt T. D. Duane

1969-01-01

396

Embryonic Hemoglobins in alpha -Thalassemia Mice.  

National Technical Information Service (NTIS)

Embryonic hemoglobins in heterozygous alpha -thalassemic and normal fetuses were compared to study the effects of the deficient alpha chain on the synthesis of hemoglobins in the nucleated embryonic erythrocytes derived from the fetal yolk sac. Visual ins...

R. A. Popp B. S. Bradshaw G. P. Hirsch

1978-01-01

397

Radiolabeling of the interferon-alpha receptor  

SciTech Connect

The action of alpha interferon (IFN-alpha) is initiated by its binding to a specific cell-surface glycoprotein, the IFN-alpha receptor, which is not well characterized. IFN-alpha A was reacted with an /sup 125/I-labeled, cleavable, heterobifunctional reagent. The derivatized IFN-alpha A was bound to human Daudi cells and photoactivated, forming a covalent IFN/receptor complex of apparent molecular weight 130,000-140,000 by SDS-polyacrylamide gel electrophoresis. Cleavage of the complex produced a new /sup 125/I-labeled 110 kDa band, representing the /sup 125/I-labeled IFN-alpha receptor free of IFN-alpha. This result provides a better estimate of the apparent molecular weight of the IFN-alpha receptor, and also provides a tool for tracking the migration of the free receptor in SDS-polyacrylamide gel electrophoresis.

Langer, J.A.

1988-12-30

398

Alpha-like calculations with MCNP  

SciTech Connect

Alpha (time-absorption eigenvalue) calculations are not an explicit calculational option in MCNP. Nevertheless, it is possible to perform alpha calculations with MCNP. Such calculations are presently either very inefficient or require special coding or cross section library modifications. However, alpha-like calculations can easily be performed with MCNP using the KCODE option with neutron energy- or time-cutoffs. These approximate alpha-like calculations are described and tested.

Parsons, D.K.

1997-11-01

399

Interaction of dihydromyricetin and alpha-amylase.  

PubMed

The interaction of dihydromyricetin (DMY) and alpha-amylase was investigated. The complex formed between DMY and alpha-amylase resulted in decreased antioxidant activity of DMY and the catalytic activity of the enzyme, as well as efficient quenching of the intrinsic fluorescence of alpha-amylase. An alpha-amylase molecule provides one binding site for a DMY molecule. These results will be useful for exploiting this compound to combat diseases efficiently. PMID:23678807

Chen, Lei; Wang, Chao; Wei, Qingyi; Ning, Zhengxiang; Yuan, Erdong

2013-03-01

400

Recent Results on the CKM Angle Alpha  

SciTech Connect

The method to measure the CKM angle {alpha} and the modes sensitive to it are discussed. It is shown that the B {yields} {rho}{rho} decays provide the most stringent constraint on {alpha}, which is found to be {alpha} = 96{sup o} {+-} 10{sup o}(stat) {+-} 4{sup o}(syst){+-} 13{sup o}(penguin).

Mihalyi, A.; /Wisconsin U., Madison

2005-10-18

401

Effectiveness of Alpha Biofeedback Therapy: Negative Results.  

ERIC Educational Resources Information Center

|Assessed the utility of alpha biofeedback training in the treatment of patients (N=66). Biofeedback and placebo biofeedback groups were given alpha or mock-alpha training sessions. Improvement on 54 variables was compared to that of no-treatment controls. Only a chance number of significant changes appeared among the groups. (Author)|

Watson, Charles G.; Herder, Joseph

1980-01-01

402

Atypical Alpha Asymmetry in Adults with ADHD  

ERIC Educational Resources Information Center

|Introduction: A growing body of literature suggests atypical cerebral asymmetry and interhemispheric interaction in ADHD. A common means of assessing lateralized brain function in clinical populations has been to examine the relative proportion of EEG alpha activity (8-12 Hz) in each hemisphere (i.e., alpha asymmetry). Increased rightward alpha

Hale, T. Sigi; Smalley, Susan L.; Hanada, Grant; Macion, James; McCracken, James T.; McGough, James J.; Loo, Sandra K.

2009-01-01