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1.
IEEE Trans Med Imaging ; 41(12): 3489-3497, 2022 12.
Artículo en Inglés | MEDLINE | ID: mdl-36251918

RESUMEN

Histopathology as a diagnostic mainstay for tissue evaluation is strictly a 2D technology. Combining and supplementing this technology with 3D imaging has been proposed as one future avenue towards refining comprehensive tissue analysis. To this end, we have developed a laboratory-based X-ray method allowing for the investigation of tissue samples in three dimensions with isotropic volume information. To assess the potential of our method for micro-morphology evaluation, we selected several kidney regions from three patients with cystic kidney disease, obstructive nephropathy and diabetic glomerulopathy. Tissue specimens were processed using our in-house-developed X-ray eosin stain and investigated with a commercial microCT and our in-house-built NanoCT. The microCT system provided overview scans with voxel sizes of [Formula: see text] and the NanoCT was employed for higher resolutions including voxel sizes from [Formula: see text] to 210 nm. We present a methodology allowing for a precise micro-morphologic investigation in three dimensions which is compatible with conventional histology. Advantages of our methodology are its versatility with respect to multi-scale investigations, being laboratory-based, allowing for non-destructive imaging and providing isotropic volume information. We believe, that after future developmental work this method might contribute to advanced multi-modal tissue diagnostics.


Asunto(s)
Técnicas Histológicas , Imagenología Tridimensional , Humanos , Imagenología Tridimensional/métodos , Microtomografía por Rayos X/métodos , Técnicas Histológicas/métodos , Eosina Amarillenta-(YS) , Riñón/diagnóstico por imagen
2.
Nat Commun ; 13(1): 5219, 2022 09 05.
Artículo en Inglés | MEDLINE | ID: mdl-36064947

RESUMEN

The development dynamics and self-organization of glandular branched epithelia is of utmost importance for our understanding of diverse processes ranging from normal tissue growth to the growth of cancerous tissues. Using single primary murine pancreatic ductal adenocarcinoma (PDAC) cells embedded in a collagen matrix and adapted media supplementation, we generate organoids that self-organize into highly branched structures displaying a seamless lumen connecting terminal end buds, replicating in vivo PDAC architecture. We identify distinct morphogenesis phases, each characterized by a unique pattern of cell invasion, matrix deformation, protein expression, and respective molecular dependencies. We propose a minimal theoretical model of a branching and proliferating tissue, capturing the dynamics of the first phases. Observing the interaction of morphogenesis, mechanical environment and gene expression in vitro sets a benchmark for the understanding of self-organization processes governing complex organoid structure formation processes and branching morphogenesis.


Asunto(s)
Carcinoma Ductal Pancreático , Neoplasias Pancreáticas , Animales , Carcinoma Ductal Pancreático/patología , Ratones , Morfogénesis , Organoides/metabolismo , Páncreas/metabolismo , Neoplasias Pancreáticas/patología , Neoplasias Pancreáticas
3.
J Eur Acad Dermatol Venereol ; 36(5): 705-716, 2022 May.
Artículo en Inglés | MEDLINE | ID: mdl-35015907

RESUMEN

BACKGROUND: Cutaneous bacterial dysbiosis is a characteristic hallmark of atopic dermatitis (AD), and it decisively influences the severity of the disease. Despite this, frequently used murine models of AD have not been characterized regarding the changes in skin microbiome communities. OBJECTIVE: To analyse the skin microbiome of two frequently used murine models for AD for assessing their applicability in translational research. METHODS: AD was induced in mice by topical application of calcipotriol or oxazolone. Following comparable elicitation of AD-like dermatitis, including IgE induction, the skin microbial communities were analysed and compared with human AD. RESULTS: We detected critical differences in the microbiota composition of diseased skin. In contrast to calcipotriol treatment, application of oxazolone induced significant changes in the cutaneous microbiota and a drastic drop of bacterial richness. Furthermore, an expansion of Staphylococci, particularly S. xylosus, was observed in the oxazolone group, also displaying positive correlations with AD key markers including pH, TEWL, IL-4, TSLP and IL-33. CONCLUSIONS: In this article, we show that (a) the model of choice to investigate AD needs to be characterized for the cutaneous microbiota if applicable and (b) the oxazolone-mediated mixed Th1-Th2 immune response triggers microbiota-induced alterations which share similarities to dysbiosis in human AD and represents therefore a suitable model for translational research on AD if alterations of the microbiome are in the focus of the investigation.


Asunto(s)
Dermatitis Atópica , Microbiota , Animales , Bacterias , Citocinas , Modelos Animales de Enfermedad , Disbiosis/inducido químicamente , Humanos , Interleucina-33 , Interleucina-4 , Ratones , Oxazolona/efectos adversos , Piel
4.
Clin Neuroradiol ; 31(3): 753-761, 2021 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-33006654

RESUMEN

BACKGROUND: For patients with acute vessel occlusions of the anterior circulation histopathology of retrieved cerebral thrombi has been reported to be associated to stroke etiology. Due to the relatively small incidence of posterior circulation stroke, exclusive histopathologic analyses are missing for this subgroup. The aim of the study was to investigate thrombus histology for patients with basilar artery occlusions and uncover differences to anterior circulation clots with respect to underlying etiology. METHODS: A total of 59 basilar thrombi were collected during intracranial mechanical recanalization and quantitatively analyzed in terms of their relative fractions of the main constituents, e.g. fibrin/platelets (F/P), red (RBC) and white blood cells (WBC). Data were compared to histopathological analyses of 122 thrombi of the anterior circulation with respect to underlying pathogenesis. RESULTS: The composition of basilar thrombi differed significantly to thrombi of the anterior circulation with an overall higher RBC amount (median fraction in % (interquartile range):0.48 (0.37-0.69) vs. 0.37 (0.28-0.50), p < 0.001) and lower F/P count (0.45 (0.21-0.58) vs. 0.57 (0.44-0.66), p < 0.001). Basilar thrombi composition did not differ between the different etiological stroke subgroups. CONCLUSION: The results depict a differing thrombus composition of basilar thrombi in comparison to anterior circulation clots with an overall higher amount of RBC. This may reflect different pathophysiologic processes between anterior and posterior circulation thrombogenesis, e.g. a larger proportion of appositional thrombus growth in the posterior circulation.


Asunto(s)
Accidente Cerebrovascular , Trombosis , Arteria Basilar/diagnóstico por imagen , Eritrocitos , Humanos , Trombectomía , Trombosis/diagnóstico por imagen
5.
J Comp Pathol ; 173: 71-82, 2019 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-31812175

RESUMEN

Pancreatic carcinomas are rare in dogs and clinical signs are mostly non-specific. The literature on clinically and pathologically characterized canine exocrine pancreatic tumours is limited to 76 cases reported since 1963. This retrospective study analysed formalin-fixed samples of pancreatic carcinomas from 22 dogs, obtained during elective exploratory surgery (n = 16) or if the dog was humanely destroyed (n = 6). Tumours were diagnosed according to the World Health Organization classification of tumours of the pancreas of domestic animals. In seven cases, blood samples taken during or shortly before surgery were analysed for concentrations of alpha-amylase, 1,2-o-dilauryl-rac-glycero-3-glutaric acid-(6'-methylresorufin) ester lipase (DGGR lipase), C-reactive protein (CRP), alanine aminotransferase, glutamate dehydrogenase, alkaline phosphatase (ALP), canine trypsin-like immunoreactivity (cTLI) and canine pancreatic lipase immunoreactivity (cPLI). Neutrophil and lymphocyte numbers were determined as part of a complete blood count. Clinical signs were non-specific and included vomiting, inappetence and diarrhoea. Acinar carcinomas were most common (19/22) and observed growth patterns included: solid (n = 14), acinar (n = 5), clear cell (n = 3), mucinous (n = 2), trabecular (n = 1) or rosette-like (n = 1), occurring as a single pattern or in combination. Ductal carcinomas were identified in three cases. Pancreatitis was a common additional histological finding; five dogs had mild and nine dogs had severe pancreatitis. cPLI, DGGR lipase, cTLI and CRP were elevated in 5/5 acinar carcinomas. All liver enzymes were elevated in three of these five animals and ALP was increased in 4/5 dogs. Two dogs with ductal pancreatic carcinomas showed normal cPLI concentrations. One had increased CRP, liver enzymes and leucocytosis with neutrophilia, the other had elevated DGGR lipase and cTLI concentrations. Clinical findings in canine pancreatic carcinomas were non-specific and simultaneous inflammation can mask the detection of the underlying neoplasm in clinical examination and laboratory testing.


Asunto(s)
Enfermedades de los Perros/patología , Neoplasias Pancreáticas/veterinaria , Animales , Perros , Neoplasias Pancreáticas
6.
Phys Rev Lett ; 122(22): 222502, 2019 Jun 07.
Artículo en Inglés | MEDLINE | ID: mdl-31283269

RESUMEN

A record number of ^{100}Sn nuclei was detected and new isotopic species toward the proton dripline were discovered at the RIKEN Nishina Center. Decay spectroscopy was performed with the high-efficiency detector arrays WAS3ABi and EURICA. Both the half-life and the ß-decay end point energy of ^{100}Sn were measured more precisely than the literature values. The value and the uncertainty of the resulting strength for the pure 0^{+}→1^{+} Gamow-Teller decay was improved to B_{GT}=4.4_{-0.7}^{+0.9}. A discrimination between different model calculations was possible for the first time, and the level scheme of ^{100}In is investigated further.

7.
J Comp Pathol ; 169: 5-19, 2019 May.
Artículo en Inglés | MEDLINE | ID: mdl-31159950

RESUMEN

Tumours of the exocrine pancreas are rare in cats and few cases are described in the literature. Cystic tumours of the pancreas are not included in the World Health Organization (WHO) international histological classification of tumours of domestic animals. The aim of this study was to characterize the pathology of primary epithelial tumours of the feline exocrine pancreas, with emphasis on cystic tumours. We reviewed tumours of the exocrine pancreas in 70 cats, including complete tumours or the entire pancreas (n = 18) and excisional biopsy samples of pancreatic tumours (n = 52). Macroscopically, the tumours were grouped as solid (n = 45) or cystic (n = 25). Solid tumours were subdivided into adenomas (n = 5) and carcinomas (n = 40) and cystic neoplasms into adenomas (n = 15), carcinomas (n = 7) and cases with diverse growth patterns (n = 3). All five grossly solid adenomas had acinar morphology, while the macroscopically solid carcinomas showed acinar (n = 17), tubular (n = 14) or mixed (n = 9) growth microscopically. Cystic adenomas had acinar (n = 2), tubular (n = 12) or mixed (n = 1) growth, while cystic carcinomas had exclusively tubular growth (n = 7). Three cases with cystic lesions showed diverse histopathological growth patterns. The clinical outcome was available in 57 cases. The majority of cats with carcinomas died or were humanely destroyed during or shortly after surgery (n = 32). However, 2/7 animals with cystic carcinomas showed longer survival times. Cats with cystic adenomas had survival times of up to 5 years. The results of this study show that cystic pancreatic tumours should be considered a differential diagnosis in cats with cystic intra-abdominal masses, even though these are not yet described in the WHO classification. Based on the relatively long survival times of cats with cystic adenomas, complete resection with subsequent histopathological examination is recommended.


Asunto(s)
Enfermedades de los Gatos/patología , Páncreas Exocrino/patología , Neoplasias Pancreáticas/veterinaria , Animales , Gatos
8.
Pathologe ; 40(2): 172-178, 2019 Mar.
Artículo en Alemán | MEDLINE | ID: mdl-30027333

RESUMEN

A systematic review of histopathology from experimental animal systems is an essential part of up-to-date biomedical research. Pathologists at university hospitals are especially and increasingly challenged by these specialized and time-consuming duties. This article presents and analyzes a new laboratory structure of comparative experimental pathology-jointly lead by veterinary and human pathologists-which might solve this problem. The focus is on the establishment and full integration of this laboratory structure into a local, regional, and nationwide biomedical research cluster. A detailed comparison with an established structure of routine histopathology laboratories discusses merits and benefits as well as disadvantages.


Asunto(s)
Investigación Biomédica , Investigación Biomédica Traslacional , Academias e Institutos , Animales , Hospitales Universitarios , Humanos , Laboratorios
9.
Sci Rep ; 7(1): 17038, 2017 12 06.
Artículo en Inglés | MEDLINE | ID: mdl-29213099

RESUMEN

Recent advances in molecular subtyping of Pancreatic Ductal Adenocarcinoma (PDAC) support individualization of therapeutic strategies in this most aggressive disease. With the emergence of various novel therapeutic strategies and neoadjuvant approaches in this quickly deteriorating disease, robust approaches for fast evaluation of therapy response are urgently needed. To this aim, we designed a preclinical imaging-guided therapy trial where genetically engineered mice harboring endogenous aggressive PDAC were treated with the MEK targeting drug refametinib, which induces rapid and profound tumor regression in this model system. Multi-parametric non-invasive imaging was used for therapy response monitoring. A significant increase in the Diffusion-Weighted Magnetic Resonance Imaging derived Apparent Diffusion Coefficient (ADC) was noted already 24 hours after treatment onset. Histopathological analyses showed increased apoptosis and matrix remodeling at this time point. Our findings suggest the ADC parameter as an early predictor of therapy response in PDAC.


Asunto(s)
Carcinoma Ductal Pancreático/patología , Neoplasias Pancreáticas/patología , Animales , Carcinoma Ductal Pancreático/diagnóstico por imagen , Carcinoma Ductal Pancreático/tratamiento farmacológico , Imagen de Difusión por Resonancia Magnética , Difenilamina/análogos & derivados , Difenilamina/uso terapéutico , Modelos Animales de Enfermedad , Humanos , Procesamiento de Imagen Asistido por Computador , Quinasas Quinasa Quinasa PAM/antagonistas & inhibidores , Quinasas Quinasa Quinasa PAM/metabolismo , Ratones , Terapia Neoadyuvante , Neoplasias Pancreáticas/diagnóstico por imagen , Neoplasias Pancreáticas/tratamiento farmacológico , Inhibidores de Proteínas Quinasas/uso terapéutico , Criterios de Evaluación de Respuesta en Tumores Sólidos , Sulfonamidas/uso terapéutico , Neoplasias Pancreáticas
10.
Oncogene ; 36(22): 3094-3103, 2017 06 01.
Artículo en Inglés | MEDLINE | ID: mdl-27941872

RESUMEN

The mechanisms of initiation of pancreatic ductal adenocarcinoma (PDAC) are still largely unknown. In the present study, we analysed the role of anterior gradient-2 (AGR2) in the earliest stages of pancreatic neoplasia. Immunohistochemical analysis of chronic pancreatitis (CP) and peritumoral areas in PDAC tissues showed that AGR2 was present in tubular complexes (TC) and early pancreatic intraepithelial neoplasia (PanINs). Moreover, AGR2 was also found in discrete subpopulations of non-transformed cells neighbouring these pre-neoplastic lesions. In primary cells derived from human patient-derived xenograft (PDX) model, flow-cytometry revealed that AGR2 was overexpressed in pancreatic cancer stem cells (CSC) compared with non-stem cancer cells. In LSL-KrasG12D;Pdx1-Cre (KC) mouse model Agr2 induction preceded the formation of pre-neoplastic lesions and their development was largely inhibited by Agr2 deletion in engineered LSL-KrasG12D;Pdx1-Cre; Agr2-/- mice. In vitro, AGR2 expression was stimulated by tunicamycin-induced endoplasmic reticulum (ER) stress in both KRAS wild-type normal pancreas cells, as well as in KRAS mutated pancreatic cancer cells and was essential for ER homoeostasis. The unfolded protein response proteins GRP78, ATF6 and XBP1s were found expressed in CP and PDAC peritumoral tissues, but in contrast to AGR2, their expression was switched off during TC and PanIN formation. Real-time PCR and ELISA analyses showed that ER stress induced a pro-inflammatory phenotype in pancreatic normal, cancer and stellate cells. Moreover, AGR2 expression was inducible by paracrine transfer of ER stress and pro-inflammation between different pancreatic cell types. Our findings demonstrate that AGR2 induced in ER-stressed and inflammatory pre-neoplastic pancreas is a potential marker of cancer progenitor cells with an important functional role in PDAC initiation.


Asunto(s)
Carcinoma Ductal Pancreático/patología , Estrés del Retículo Endoplásmico/fisiología , Mucoproteínas/metabolismo , Neoplasias Pancreáticas/patología , Animales , Carcinoma Ductal Pancreático/genética , Carcinoma Ductal Pancreático/metabolismo , Transformación Celular Neoplásica/genética , Transformación Celular Neoplásica/metabolismo , Transformación Celular Neoplásica/patología , Modelos Animales de Enfermedad , Chaperón BiP del Retículo Endoplásmico , Humanos , Ratones , Mucoproteínas/biosíntesis , Mucoproteínas/deficiencia , Mucoproteínas/genética , Proteínas Oncogénicas , Neoplasias Pancreáticas/genética , Neoplasias Pancreáticas/metabolismo , Proteínas Proto-Oncogénicas p21(ras)/genética , Proteínas Proto-Oncogénicas p21(ras)/metabolismo
11.
Phys Rev Lett ; 116(16): 162501, 2016 Apr 22.
Artículo en Inglés | MEDLINE | ID: mdl-27152796

RESUMEN

Several new isotopes, ^{96}In, ^{94}Cd, ^{92}Ag, and ^{90}Pd, have been identified at the RIKEN Nishina Center. The study of proton drip-line nuclei in the vicinity of ^{100}Sn led to the discovery of new proton emitters ^{93}Ag and ^{89}Rh with half-lives in the submicrosecond range. The systematics of the half-lives of odd-Z nuclei with T_{z}=-1/2 toward ^{99}Sn shows a stabilizing effect of the Z=50 shell closure. Production cross sections for nuclei in the vicinity of ^{100}Sn measured at different energies and target thicknesses were compared to the cross sections calculated by epax taking into account contributions of secondary reactions in the primary target.

12.
Oncogenesis ; 5: e210, 2016 Mar 14.
Artículo en Inglés | MEDLINE | ID: mdl-26974205

RESUMEN

We previously produced pigs with a latent oncogenic TP53 mutation. Humans with TP53 germline mutations are predisposed to a wide spectrum of early-onset cancers, predominantly breast, brain, adrenal gland cancer, soft tissue sarcomas and osteosarcomas. Loss of p53 function has been observed in >50% of human cancers. Here we demonstrate that porcine mesenchymal stem cells (MSCs) convert to a transformed phenotype after activation of latent oncogenic TP53(R167H) and KRAS(G12D), and overexpression of MYC promotes tumorigenesis. The process mimics key molecular aspects of human sarcomagenesis. Transformed porcine MSCs exhibit genomic instability, with complex karyotypes, and develop into sarcomas on transplantation into immune-deficient mice. In pigs, heterozygous knockout of TP53 was sufficient for spontaneous osteosarcoma development in older animals, whereas homozygous TP53 knockout resulted in multiple large osteosarcomas in 7-8-month-old animals. This is the first report that engineered mutation of an endogenous tumour-suppressor gene leads to invasive cancer in pigs. Unlike in Trp53 mutant mice, osteosarcoma developed in the long bones and skull, closely recapitulating the human disease. These animals thus promise a model for juvenile osteosarcoma, a relatively uncommon but devastating disease.

13.
J Comp Pathol ; 153(2-3): 131-4, 2015.
Artículo en Inglés | MEDLINE | ID: mdl-26142615

RESUMEN

A 16-year-old Friesian gelding with relapsing colic was humanely destroyed during diagnostic laparotomy due to suspected abdominal neoplasia. On post-mortem examination, the pancreas appeared as a firm mass (20 × 8 × 8 cm). The cut surface had a lobular structure with multiple cavities. Histological examination revealed severe chronic fibrosing pancreatitis with acinar-ductal metaplasia and duct dysplasia, which was considered to be the cause of the recurrent colic. Formation of tubular complexes within a background of acinar-ductal metaplasia is similar to the regressive lesions detected in the human pancreas in the context of inflammation, duct obstruction, cystic fibrosis and neoplasia. Pancreatic acinar-ductal metaplasia and ductal dysplasia are considered to be preneoplastic conditions in man and in the mouse.


Asunto(s)
Enfermedades de los Caballos/patología , Conductos Pancreáticos/patología , Pancreatitis Crónica/veterinaria , Animales , Caballos , Masculino , Metaplasia , Pancreatitis Crónica/patología
14.
Phys Rev Lett ; 114(19): 192501, 2015 May 15.
Artículo en Inglés | MEDLINE | ID: mdl-26024165

RESUMEN

The ß-decay half-lives of 110 neutron-rich isotopes of the elements from _{37}Rb to _{50}Sn were measured at the Radioactive Isotope Beam Factory. The 40 new half-lives follow robust systematics and highlight the persistence of shell effects. The new data have direct implications for r-process calculations and reinforce the notion that the second (A≈130) and the rare-earth-element (A≈160) abundance peaks may result from the freeze-out of an (n,γ)⇄(γ,n) equilibrium. In such an equilibrium, the new half-lives are important factors determining the abundance of rare-earth elements, and allow for a more reliable discussion of the r process universality. It is anticipated that universality may not extend to the elements Sn, Sb, I, and Cs, making the detection of these elements in metal-poor stars of the utmost importance to determine the exact conditions of individual r-process events.

15.
Phys Rev Lett ; 113(13): 132502, 2014 Sep 26.
Artículo en Inglés | MEDLINE | ID: mdl-25302883

RESUMEN

Delayed γ-ray cascades, originating from the decay of (6⁺) isomeric states, in the very neutron-rich, semimagic isotopes (136,138)Sn have been observed following the projectile fission of a ²³8U beam at RIBF, RIKEN. The wave functions of these isomeric states are proposed to be predominantly a fully aligned pair of f(7/2) neutrons. Shell-model calculations, performed using a realistic effective interaction, reproduce well the energies of the excited states of these nuclei and the measured transition rates, with the exception of the B(E2;6⁺→4⁺) rate of ¹³6Sn, which deviates from a simple seniority scheme. Empirically reducing the νf(7/2)(2) orbit matrix elements produces a 41⁺ state with almost equal seniority 2 and 4 components, correctly reproducing the experimental B(E2;6⁺→4⁺) rate of ¹³6Sn. These data provide a key benchmark for shell-model interactions far from stability.

16.
Phys Rev Lett ; 113(4): 042502, 2014 Jul 25.
Artículo en Inglés | MEDLINE | ID: mdl-25105611

RESUMEN

A new isomer with a half-life of 23.0(8) ms has been identified at 2406 keV in (126)Pd and is proposed to have a spin and parity of 10(+) with a maximally aligned configuration comprising two neutron holes in the 1h(11/2) orbit. In addition to an internal-decay branch through a hindered electric octupole transition, ß decay from the long-lived isomer was observed to populate excited states at high spins in (126)Ag. The smaller energy difference between the 10(+) and 7(-) isomers in (126)Pd than in the heavier N=80 isotones can be interpreted as being ascribed to the monopole shift of the 1h(11/2) neutron orbit. The effects of the monopole interaction on the evolution of single-neutron energies below (132)Sn are discussed in terms of the central and tensor forces.

17.
Phys Rev Lett ; 112(13): 132501, 2014 Apr 04.
Artículo en Inglés | MEDLINE | ID: mdl-24745408

RESUMEN

A low-lying state in 131In82, the one-proton hole nucleus with respect to double magic 132Sn, was observed by its γ decay to the Iπ=1/2- ß-emitting isomer. We identify the new state at an excitation energy of Ex=1353 keV, which was populated both in the ß decay of 131Cd83 and after ß-delayed neutron emission from 132Cd84, as the previously unknown πp3/2 single-hole state with respect to the 132Sn core. Exploiting this crucial new experimental information, shell-model calculations were performed to study the structure of experimentally inaccessible N=82 isotones below 132Sn. The results evidence a surprising absence of proton subshell closures along the chain of N=82 isotones. The consequences of this finding for the evolution of the N=82 shell gap along the r-process path are discussed.

18.
Phys Rev Lett ; 111(15): 152501, 2013 Oct 11.
Artículo en Inglés | MEDLINE | ID: mdl-24160593

RESUMEN

The level structures of the very neutron-rich nuclei 128Pd and 126Pd have been investigated for the first time. In the r-process waiting-point nucleus 128Pd, a new isomer with a half-life of 5.8(8) µs is proposed to have a spin and parity of 8(+) and is associated with a maximally aligned configuration arising from the g(9/2) proton subshell with seniority υ=2. For 126Pd, two new isomers have been identified with half-lives of 0.33(4) and 0.44(3) µs. The yrast 2(+) energy is much higher in 128Pd than in 126Pd, while the level sequence below the 8(+) isomer in 128Pd is similar to that in the N=82 isotone 130Cd. The electric quadrupole transition that depopulates the 8(+) isomer in 128Pd is more hindered than the corresponding transition in 130Cd, as expected in the seniority scheme for a semimagic, spherical nucleus. These experimental findings indicate that the shell closure at the neutron number N=82 is fairly robust in the neutron-rich Pd isotopes.

19.
Phys Rev Lett ; 109(18): 182501, 2012 Nov 02.
Artículo en Inglés | MEDLINE | ID: mdl-23215274

RESUMEN

Excited states in (38,40,42) Si nuclei have been studied via in-beam γ-ray spectroscopy with multinucleon removal reactions. Intense radioactive beams of ^{40}S and (44)S provided at the new facility of the RIKEN Radioactive Isotope Beam Factory enabled γ-γ coincidence measurements. A prominent γ line observed with an energy of 742(8) keV in (42) Si confirms the 2(+) state reported in an earlier study. Among the γ lines observed in coincidence with the 2^{+} → 0+ transition, the most probable candidate for the transition from the yrast 4(+) state was identified, leading to a 4(1)+) energy of 2173(14) keV. The energy ratio of 2.93(5) between the 2(1)+ and 4(1)(+) states indicates well-developed deformation in (42) Si at N = 28 and Z = 14. Also for 38,40)Si energy ratios with values of 2.09(5) and 2.56(5) were obtained. Together with the ratio for (42)Si, the results show a rapid deformation development of Si isotopes from N = 24 to N = 28.

20.
Nature ; 486(7403): 341-5, 2012 Jun 20.
Artículo en Inglés | MEDLINE | ID: mdl-22722192

RESUMEN

The shell structure of atomic nuclei is associated with 'magic numbers' and originates in the nearly independent motion of neutrons and protons in a mean potential generated by all nucleons. During ß(+)-decay, a proton transforms into a neutron in a previously not fully occupied orbital, emitting a positron-neutrino pair with either parallel or antiparallel spins, in a Gamow-Teller or Fermi transition, respectively. The transition probability, or strength, of a Gamow-Teller transition depends sensitively on the underlying shell structure and is usually distributed among many states in the neighbouring nucleus. Here we report measurements of the half-life and decay energy for the decay of (100)Sn, the heaviest doubly magic nucleus with equal numbers of protons and neutrons. In the ß-decay of (100)Sn, a large fraction of the strength is observable because of the large decay energy. We determine the largest Gamow-Teller strength so far measured in allowed nuclear ß-decay, establishing the 'superallowed' nature of this Gamow-Teller transition. The large strength and the low-energy states in the daughter nucleus, (100)In, are well reproduced by modern, large-scale shell model calculations.

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