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1.
Phys Rev Lett ; 132(14): 142502, 2024 Apr 05.
Artigo em Inglês | MEDLINE | ID: mdl-38640383

RESUMO

A precision measurement of the ß^{+} decay of ^{8}B was performed using the Beta-decay Paul Trap to determine the ß-ν angular correlation coefficient a_{ßν}. The experimental results were combined with new ab initio symmetry-adapted no-core shell-model calculations to yield the second-most precise measurement from Gamow-Teller decays, a_{ßν}=-0.3345±0.0019_{stat}±0.0021_{syst}. This value agrees with the standard model value of -1/3 and improves uncertainties in ^{8}B by nearly a factor of 2. By combining results from ^{8}B and ^{8}Li, a tight limit on tensor current coupling to right-handed neutrinos was obtained. A recent global evaluation of all other precision ß decay studies suggested a nonzero value for right-handed neutrino coupling in contradiction with the standard model at just above 3σ. The present results are of comparable sensitivity and do not support this finding.

2.
Phys Rev Lett ; 130(19): 192502, 2023 May 12.
Artigo em Inglês | MEDLINE | ID: mdl-37243659

RESUMO

We present the first measurement of the α-ß-ν angular correlation in the Gamow-Teller ß^{+} decay of ^{8}B. This was accomplished using the Beta-decay Paul Trap, expanding on our previous work on the ß^{-} decay of ^{8}Li. The ^{8}B result is consistent with the V-A electroweak interaction of the standard model and, on its own, provides a limit on the exotic right-handed tensor current relative to the axial-vector current of |C_{T}/C_{A}|^{2}<0.013 at the 95.5% confidence level. This represents the first high-precision angular correlation measurements in mirror decays and was made possible through the use of an ion trap. By combining this ^{8}B result with our previous ^{8}Li results, we demonstrate a new pathway for increased precision in searches for exotic currents.

3.
Phys Rev Lett ; 131(26): 262701, 2023 Dec 29.
Artigo em Inglês | MEDLINE | ID: mdl-38215364

RESUMO

Nuclear isomer effects are pivotal in understanding nuclear astrophysics, particularly in the rapid neutron-capture process where the population of metastable isomers can alter the radioactive decay paths of nuclei produced during astrophysical events. The ß-decaying isomer ^{128m}Sb was identified as potentially impactful since the ß-decay pathway along the A=128 isobar funnels into this state bypassing the ground state. We report the first direct mass measurements of the ^{128}Sb isomer and ground state using the Canadian Penning Trap mass spectrometer at Argonne National Laboratory. We find mass excesses of -84564.8(25) keV and -84608.8(21) keV, respectively, resulting in an excitation energy for the isomer of 43.9(33) keV. These results provide the first key nuclear data input for understanding the role of ^{128m}Sb in nucleosynthesis, and we show that it will influence the flow of the rapid neutron-capture process.

4.
Phys Rev Lett ; 128(20): 202502, 2022 May 20.
Artigo em Inglês | MEDLINE | ID: mdl-35657880

RESUMO

The electroweak interaction in the standard model is described by a pure vector-axial-vector structure, though any Lorentz-invariant component could contribute. In this Letter, we present the most precise measurement of tensor currents in the low-energy regime by examining the ß-ν[over ¯] correlation of trapped ^{8}Li ions with the Beta-decay Paul Trap. We find a_{ßν}=-0.3325±0.0013_{stat}±0.0019_{syst} at 1σ for the case of coupling to right-handed neutrinos (C_{T}=-C_{T}^{'}), which is consistent with the standard model prediction.

5.
Phys Rev Lett ; 120(26): 262702, 2018 Jun 29.
Artigo em Inglês | MEDLINE | ID: mdl-30004776

RESUMO

The Canadian Penning Trap mass spectrometer at the Californium Rare Isotope Breeder Upgrade (CARIBU) facility was used to measure the masses of eight neutron-rich isotopes of Nd and Sm. These measurements are the first to push into the region of nuclear masses relevant to the formation of the rare-earth abundance peak at A∼165 by the rapid neutron-capture process. We compare our results with theoretical predictions obtained from "reverse engineering" the mass surface that best reproduces the observed solar abundances in this region through a Markov chain Monte Carlo technique. Our measured masses are consistent with the reverse-engineering predictions for a neutron star merger wind scenario.

6.
Phys Rev Lett ; 120(18): 182502, 2018 May 04.
Artigo em Inglês | MEDLINE | ID: mdl-29775351

RESUMO

The structure of deformed neutron-rich nuclei in the rare-earth region is of significant interest for both the astrophysics and nuclear structure fields. At present, a complete explanation for the observed peak in the elemental abundances at A∼160 eludes astrophysicists, and models depend on accurate quantities, such as masses, lifetimes, and branching ratios of deformed neutron-rich nuclei in this region. Unusual nuclear structure effects are also observed, such as the unexpectedly low energies of the first 2^{+} levels in some even-even nuclei at N=98. In order to address these issues, mass and ß-decay spectroscopy measurements of the ^{160}Eu_{97} and ^{162}Eu_{99} nuclei were performed at the Californium Rare Isotope Breeder Upgrade radioactive beam facility at Argonne National Laboratory. Evidence for a gap in the single-particle neutron energies at N=98 and for large deformation (ß_{2}∼0.3) is discussed in relation to the unusual phenomena observed at this neutron number.

7.
Phys Rev Lett ; 115(18): 182501, 2015 Oct 30.
Artigo em Inglês | MEDLINE | ID: mdl-26565463

RESUMO

In the standard model, the weak interaction is formulated with a purely vector-axial-vector (V-A) structure. Without restriction on the chirality of the neutrino, the most general limits on tensor currents from nuclear ß decay are dominated by a single measurement of the ß-ν[over ¯] correlation in ^{6}He ß decay dating back over a half century. In the present work, the ß-ν[over ¯]-α correlation in the ß decay of ^{8}Li and subsequent α-particle breakup of the ^{8}Be^{*} daughter was measured. The results are consistent with a purely V-A interaction and in the case of couplings to right-handed neutrinos (C_{T}=-C_{T}^{'}) limits the tensor fraction to |C_{T}/C_{A}|^{2}<0.011 (95.5% C.L.). The measurement confirms the ^{6}He result using a different nuclear system and employing modern ion-trapping techniques subject to different systematic uncertainties.

8.
Phys Rev Lett ; 111(6): 061102, 2013 Aug 09.
Artigo em Inglês | MEDLINE | ID: mdl-23971550

RESUMO

The Canadian Penning Trap mass spectrometer has made mass measurements of 33 neutron-rich nuclides provided by the new Californium Rare Isotope Breeder Upgrade facility at Argonne National Laboratory. The studied region includes the 132Sn double shell closure and ranges in Z from In to Cs, with Sn isotopes measured out to A=135, and the typical measurement precision is at the 100 ppb level or better. The region encompasses a possible major waiting point of the astrophysical r process, and the impact of the masses on the r process is shown through a series of simulations. These first-ever simulations with direct mass information on this waiting point show significant increases in waiting time at Sn and Sb in comparison with commonly used mass models, demonstrating the inadequacy of existing models for accurate r-process calculations.

9.
Phys Rev Lett ; 110(9): 092501, 2013 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-23496704

RESUMO

A novel technique for ß-delayed neutron spectroscopy has been demonstrated using trapped ions. The neutron-energy spectrum is reconstructed by measuring the time of flight of the nuclear recoil following neutron emission, thereby avoiding all the challenges associated with neutron detection, such as backgrounds from scattered neutrons and γ rays and complicated detector-response functions. (137)I(+) ions delivered from a (252)Cf source were confined in a linear Paul trap surrounded by radiation detectors, and the ß-delayed neutron-energy spectrum and branching ratio were determined by detecting the ß(-) and recoil ions in coincidence. Systematic effects were explored by determining the branching ratio three ways. Improvements to achieve higher detection efficiency, better energy resolution, and a lower neutron-energy threshold are proposed.

10.
Phys Rev Lett ; 110(9): 092502, 2013 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-23496705

RESUMO

A measurement of the α-ß-ν[over ¯] angular correlation in the Gamow-Teller decay (8)Li→(8)Be(*)+ν[over ¯]+ß, (8)Be(*)→α+α has been performed using ions confined in a linear Paul trap surrounded by silicon detectors. The energy difference spectrum of the α particles emitted along and opposite the direction of the ß particle is consistent with the standard model prediction and places a limit of 3.1% (95.5% confidence level) on any tensor contribution to the decay. From this result, the amplitude of any tensor component C(T) relative to that of the dominant axial-vector component C(A) of the electroweak interaction is limited to |C(T)/C(A)|<0.18 (95.5% confidence level). This experimental approach is facilitated by several favorable features of the (8)Li ß decay and has different systematic effects than the previous ß-ν[over ¯] correlation results for a pure Gamow-Teller transition obtained from studying (6)He ß decay.

11.
RSC Adv ; 13(19): 13240-13251, 2023 Apr 24.
Artigo em Inglês | MEDLINE | ID: mdl-37123999

RESUMO

Deoxyglucose conjugated nanoparticles with persistent luminescence have shown theragnostic potential. In this study, deoxyglucose-conjugated nano-particles with persistent luminescence properties were synthesized, and their theragnostic potential was evaluated in fibrosarcoma cancer cells and a tumor model. The uptake of nano-formulation was found to be higher in mouse fibrosarcoma (WEHI-164) cells cultured in a medium without glucose. Nanoparticles showed a higher killing ability for cancer cells compared to normal cells. A significant accumulation of nanoparticles to the tumor site in mice was evident by the increased tumor/normal leg ratio, resulting in a significant decrease in tumor volume and weight. Histopathological studies showed a significant decrease in the number of dividing mitotic cells but a greater number of apoptotic/necrotic cells in nanoparticle-treated tumor tissues, which was correlated with a lower magnitude of Ki-67 expression (a proliferation marker). Consequently, our results showed the potential of our nano-formulation for cancer theragnosis.

12.
Indian J Exp Biol ; 48(10): 1002-7, 2010 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-21299043

RESUMO

Dielectric constant and loss factor of Raj-4120 variety of Indian wheat were determined in powder form (grain size 125 to 150 micron) at room temperature. Microwaves at three different frequencies were employed in C-band, X-band and Ku-band respectively for investigating frequency dependence of dielectric parameters of the sample. Bulk dielectric values of the sample were determined by employing the dielectric mixture relations, such as, half power mixture equation, Landau and Lifshitz, Looyenga equation etc.


Assuntos
Análise de Alimentos/métodos , Triticum/química , Espectroscopia Dielétrica , Índia , Micro-Ondas , Pós
13.
Sci Rep ; 8(1): 14766, 2018 10 03.
Artigo em Inglês | MEDLINE | ID: mdl-30283083

RESUMO

Monodispersed Fe3O4 magnetic nanoparticles (MNPs) having size of 7 nm have been prepared from iron oleate and made water dispersible by functionalization for biomedical applications. Three different reactions employing thioglycolic acid, aspartic acid and aminophosphonate were performed on oleic acid coated Fe3O4. In order to achieve a control on particle size, the pristine nanoparticles were heated in presence of ferric oleate which led to increase in size from 7 to 11 nm. Reaction parameters such as rate of heating, reaction temperature and duration of heating have been studied. Shape of particles was found to change from spherical to cuboid. The cuboid shape in turn enhances magneto-crystalline anisotropy (Ku). Heating efficacy of these nanoparticles for hyperthermia was also evaluated for different shapes and sizes. We demonstrate heat generation from these MNPs for hyperthermia application under alternating current (AC) magnetic field and optimized heating efficiency by controlling morphology of particles. We have also studied intra-cellular uptake and localization of nanoparticles and cytotoxicity under AC magnetic field in human breast carcinoma cell line.


Assuntos
Neoplasias da Mama/terapia , Compostos Férricos/uso terapêutico , Hipertermia Induzida/métodos , Nanopartículas de Magnetita/uso terapêutico , Anisotropia , Neoplasias da Mama/patologia , Feminino , Compostos Férricos/química , Humanos , Ferro/química , Células MCF-7 , Campos Magnéticos , Nanopartículas de Magnetita/química , Temperatura , Água/química
14.
J Mater Chem B ; 3(27): 5455-5466, 2015 Jul 21.
Artigo em Inglês | MEDLINE | ID: mdl-32262517

RESUMO

This investigation reports the preparation of agglomerated Fe3O4 nanoparticles and evaluation of its utility as a viable carrier in the preparation of radiolanthanides as potential therapeutic agents for the treatment of arthritis. The material was synthesized by a chemical route and characterized by XRD, FT-IR, SEM, EDX and TEM analysis. The surface of agglomerated particle possessed ion pairs (-O-:Na+) after dispersing particles in a NaHCO3 solution at pH = 7 which is conducive for radiolanthanide (*Ln = 90Y, 153Sm, 166Ho, 169Er, 177Lu) loading by replacement of Na+ ions with tripositive radiolanthanide ions. Radiolanthanide-loaded particulates exhibited excellent in vitro stability up to ∼3 half-lives of the respective lanthanide radionuclides when stored in normal saline at 37 °C. The radiochemical purities of the loaded particulates were found to be retained to the extent of >70% after 48 h of storage when challenged by a strong chelator DTPA present at a concentration as high as 5 mM, indicating fairly strong chemical association of lanthanides with agglomerated Fe3O4 nanoparticles. Biodistribution studies of 90Y and 166Ho-loaded particulates carried out after intra-articular injection into one of the knee joints of a normal Wistar rat revealed near-complete retention of the radioactive preparations (>98% of the administered radioactivity) within the joint cavity even after 72 h post injection. This was further confirmed by sequential whole-body radio-luminescence imaging. These experimental results are indicative of the potential use of radiolanthanide-loaded agglomerated Fe3O4 nanoparticles for the treatment of arthritis.

15.
J Am Soc Mass Spectrom ; 6(12): 1243-6, 1995 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-24214076

RESUMO

A critical discussion is given of the suggestion by Dougherty et al. (J. Am. Soc. Mass Spectrom. 1994, 5, 120) that the (12)C60 molecule replace the (12)C atom as the primary standard of atomic mass. Adoption of the proposed standard would require that the unified atomic weight/mass scale, finally achieved with much difficulty in 1960, be abandoned without demonstrable benefit. Furthermore, the proposed standard has a molecular mass that is inherently ambiguous at a level that makes it unacceptable for that purpose.

16.
IEEE Trans Image Process ; 6(3): 407-13, 1997.
Artigo em Inglês | MEDLINE | ID: mdl-18282936

RESUMO

This paper addresses the problem of identification of appropriate autoregressive (AR) components to describe textural regions of digital images by a general class of two-dimensional (2-D) AR models. In analogy with univariate time series, the proposed technique first selects a neighborhood set of 2-D lag variables corresponding to the significant multiple partial auto-correlation coefficients. A matrix is then suitably formed from these 2-D lag variables. Using singular value decomposition (SVD) and orthonormal with column pivoting factorization (QRcp) techniques, the prime information of this matrix corresponding to different pseudoranks is obtained. Schwarz's (1978) information criterion (SIG) is then used to obtain the optimum set of 2-D lag variables, which are the appropriate autoregressive components of the model for a given textural image. A four-class texture classification scheme is illustrated with such models and a comparison of the technique with the work of Chellappa and Chatterjee (1985) is provided.

17.
J Assoc Physicians India ; 27(12): 1071-4, 1979 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-549916

RESUMO

PIP: This study examines the effects of oral contraceptives on the incidence and fluctuation of sex chromatin during the different phase of menstrual cycle. Buccal smears were analyzed biweekly to determine the sex chromatin count of 63 normal female medical students (group A) aged 17 to 22 years (mean age, 18.56 + or - 1.48 years). A second group (B) consisting of 15 married women received oral contraceptives (Primovalar 50) for 6 months. Smears were also collected for 3 consecutive menstrual cycles. Three phases of menstrual cycles were identified: 1) preovulatory, subdivided into 1a (menstruation) and 1b (proliferative phase); 2) ovulatory phase, and 3) postovulatory phase. The sex chromatin count was found to be higher at midcycle and was accompanied by rise in basal body temperature and appearance of midcycle symptoms. Rise in count from phase 1b to phase 3 was highly significant at p .001. Normal subjects had a significantly higher mean sex chromatin incidence in contrast to pillusers who exhibited a decreased sex chromatin count throughout the menstrual cycle.^ieng


Assuntos
Anticoncepcionais Orais Sintéticos/farmacologia , Anticoncepcionais Orais/farmacologia , Menstruação , Cromatina Sexual/efeitos dos fármacos , Adolescente , Adulto , Contagem de Células , Feminino , Humanos
18.
Indian J Physiol Pharmacol ; 21(1): 69-71, 1977.
Artigo em Inglês | MEDLINE | ID: mdl-873595

RESUMO

Copper and Zinc have been found to be potent inhibitors of pseudo-cholinesterase of human plasma and true-cholinesterase of erythrocytes and rat brain.


Assuntos
Inibidores da Colinesterase , Cobre/farmacologia , Zinco/farmacologia , Animais , Encéfalo/enzimologia , Colinesterases/sangue , Eritrócitos/enzimologia , Humanos , Técnicas In Vitro , Ratos
19.
Eplasty ; 13: e18, 2013.
Artigo em Inglês | MEDLINE | ID: mdl-23641297

RESUMO

OBJECTIVES: Otophyma is a rare condition that can present as the end stage of any chronic inflammatory disease affecting the ear such as rosacea, eczema, or otitis externa. It can result in conductive hearing loss, low self-esteem, and social embarrassment. This report highlights a case of otophyma treated successfully using a full-thickness skin graft. METHODS: We present a case of a 41-year-old lady referred to our department with a 23-year history of bilateral otophyma. During this time, her hearing progressively diminished as the swelling occluded her external auditory meatus. She had been unsuccessfully managed for years with topical emollients, steroids, and regular ear toileting. RESULT: She was treated by excision of the phymatous tissue and full-thickness grafting, which resulted in a patent external auditory meatus and an improvement in her hearing. CONCLUSIONS: The use of a full-thickness skin graft is one of the many treatment options available for the treatment of otophyma. We present a literature review on this uncommon condition and a discussion on the various treatment options available to the patient.

20.
Case Rep Surg ; 2013: 765279, 2013.
Artigo em Inglês | MEDLINE | ID: mdl-23401838

RESUMO

We present the first reported case of the prophylactic use of lipid emulsion therapy in the removal of an extensive, circumferential malignant melanoma in a morbidly obese patient, under local anaesthetic. The advantages of this technique allowed the patient to avoid intraoperative invasive monitoring and postoperative critical care admission and assisted during the operation by rotating her leg when needed. This is a useful technique that can be employed in urgent cases where there is a need to excise extensive skin malignancies in patients who are unsuitable for general or regional anaesthesia.

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