Neighboring Nuclei Research Articles

Electronic Force Density Fields: Insights into Partial Bonds, Transition States, and Chemical Structure Evolution.

This paper presents the quantum-topological binding approach, in which the electrostatic and total static force density fields, Fes(r) and , together with the electron density gradient field ∇ρ(r), are simultaneously analyzed to elucidate the chemical structure of transition states and the nature of interatomic interactions for semibroken semiformed partial chemical bonds. The approach attributes the discrepancies between the force fields and Fes(r) to the nonclassical electron-electron interaction effects. The internuclear gap between the zero-flux boundaries of Fes(r) and ∇ρ(r) indicates the interatomic charge transfer phenomenon (ICT) that occurs upon the formation of a system from free atoms. Concomitantly, the mismatch of the zero-flux surfaces defined in and ∇ρ(r) can be interpreted as a phenomenon of the electron-transfer-induced quantum chemical response (QCR), which originates from the electron exchange correlation. Our study permits the assertion of parallels between partial bonds and noncovalent interactions, as both typically exhibit incomplete QCRs, indicating the partial electron sharing of the transferred density. The changes in atomic and pseudoatomic charges are employed to describe the evolution of the chemical structure upon the substitution reaction. It is observed that the acquired difference in the actual atomic electronegativity causes polarization upon the heterolytic breaking of virtually nonpolar bonds. It is further proposed that the proximity of closely related stationary states along the reaction path on a potential energy hypersurface implies their similarity in the manifestation of the ICT and sympathetic QCR. Furthermore, the involvement of an electron pair in a partial bond facilitates its delocalization through the attraction by the static forces and Fes(r) to a neighboring nucleus and through the smearing by the Pauli kinetic force FP(r).

Step-edge-guided nucleation and growth mode transition of α-Ga2O3 heteroepitaxy on vicinal sapphire

Abstract Controlling the epitaxial growth mode of semiconductor layers is crucial for optimizing material properties and device performance. In this work, the growth mode of α-Ga2O3 heteroepitaxial layers was modulated by tuning miscut angles (θ) from 0° to 7° off the (10-10) direction of sapphire (0002) substrate. On flat sapphire surfaces, the growth undergoes a typical three-dimensional (3D) growth mode due to the random nucleation on wide substrate terraces, as evidenced by the hillock morphology and high dislocation densities. As the miscut angle increases to θ=5°, the terrace width of sapphire substrate is comparable to the distance between neighboring nuclei, and consequently, the nucleation is guided by terrace edges, which energetically facilitates the growth mode transition into the desirable two-dimensional coherent growth. Consequently, the mean surface roughness decreases to only 0.62 nm, accompanied by a significant reduction in screw and edge dislocations to 0.16×107 cm-2 and 3.58×109 cm-2, respectively. However, the further increment of miscut angles to θ=7° shrink the terrace width less than nucleation distance, and the step-bunching growth mode is dominant. In this circumstance, the misfit strain is released in the initial growth stage, resulting in surface morphology degradation and increased dislocation densities.

Exotic collective excitation patterns in triaxially deformed <sup>131</sup>Ba

<sec>In the last two decades, several unique phenomena in triaxially deformed nuclei, such as chiral doublet bands and wobbling motion have been revealed. Up to now, there are still many open questions which require further experimental and theoretical studies. To explore the collective motion in <sup>131</sup>Ba, an experiment was performed using the XTU Tandem accelerator in the Legnaro laboratory, Italy. High-spin states of <sup>131</sup>Ba have been populated via the heavy-ion fusion-evaporation <sup>122</sup>Sn(<sup>13</sup>C, 4n) reaction. <i>γ</i>-rays, charged particles and neutrons emitted from the residues were detected by the GALILEO array, EUCLIDES silicon ball, and the Neutron Wall, respectively. A total of 1.2<inline-formula><tex-math id="M12">\begin{document}$ \times $\end{document}</tex-math><alternatives><graphic specific-use="online" xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="11-20240212_M12.jpg"/><graphic specific-use="print" xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="11-20240212_M12.png"/></alternatives></inline-formula>10<sup>9</sup> triple- or higher-fold events were collected by the GALILEO data acquisition system. The <i>γ</i>-<i>γ</i>-<i>γ</i> coincidence events were sorted into a three-dimensional histogram (cube) and the analysis was carried out with the RADWARE and GASPWARE software packages.</sec><sec>Through analysis of the coincidences between <i>γ</i>-rays, the most comprehensive level schemes of <sup>131</sup>Ba to date was deduced from the present work. The extended level-scheme consists of 15 rotational bands, and newly observed transitions are marked in red. Three nearly degenerate pairs of doublet bands (Band 3–8) are identified in <sup>131</sup>Ba. Two pairs of chiral doublets (Band 3–6) with configuration <inline-formula><tex-math id="M20">\begin{document}$ {\textit{\pi}}h_{11/2}(g_{7/2},d_{5/2}){\otimes}{\nu}h_{11/2} $\end{document}</tex-math><alternatives><graphic specific-use="online" xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="11-20240212_M20.jpg"/><graphic specific-use="print" xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="11-20240212_M20.png"/></alternatives></inline-formula> are interpreted as a set of pseudospin-chiral quartet bands. The quartet bands are fed by another pair of chiral doublet bands (Band 7–8) built on a <inline-formula><tex-math id="M21">\begin{document}$ {\textit{\pi}}h^2_{11/2}{\otimes}{\nu}h_{11/2} $\end{document}</tex-math><alternatives><graphic specific-use="online" xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="11-20240212_M21.jpg"/><graphic specific-use="print" xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="11-20240212_M21.png"/></alternatives></inline-formula> configuration via a series of enhanced E1 transitions. We extracted the energy displacement <i>δ</i>E and the B(E1)/B(E2) branching ratios between the positive-parity band 3 and the negative-parity band 7 in <sup>131</sup>Ba and in comparison with those in <sup>124</sup>Ba, <sup>224</sup>Th, <sup>133</sup>Ce and <sup>135</sup>Nd. The energy displacement <i>δ</i>E and the B(E1)/B(E2) branching ratios in <sup>131</sup>Ba are comparable with those in <sup>124</sup>Ba but deviate appreciably from those in <sup>224</sup>Th which has been reported to have stable octupole deformation. The results indicate the existence of octupole correlations in <sup>131</sup>Ba without stable octupole deformation. A new rotational band (Band 10) discovered in the low-spin region exhibits a level structure similar to a wobbling band. Assuming it as a wobbling band, the wobbling frequency was extracted and compared with other reported wobbling bands in the neighboring nuclei. The wobbling frequency of this band decreases with increasing angular momentum, and even exhibits negative value at the highest spin. Considering that the wobbling phonon should contribute a positive amount to the excitation energy, this band is unlikely to be explained by this mechanism. The band may originate from other collective excitation mechanisms such as <i>γ</i> vibration. The newly identified rotational band (Band 9) composed of M1 transitions is tentatively assigned as a magnetic rotational band through a systematic analysis of the level structure. Finally, the configurations of other 4 bands, Band 12-15, are also suggested based on previous researches and the extracted quasiparticle alignments.</sec>

On the role of selective nucleation and growth to recrystallization texture development in a Mg–Gd–Zn alloy

One of the main material properties altered by rare earth additions in magnesium alloys is texture, which can be specifically adjusted to enhance ductility and formability. The current study aims at illuminating the texture selection process in a Mg–0.073at%Gd–0.165at%Zn alloy by investigating recrystallization nucleation and early nucleus growth during static recrystallization. An as-cast sample of the investigated alloy was deformed in uniaxial compression at 200 °C till 40% strain and was then cut into two halves for subsequent microstructure characterization via ex situ and quasi in situ EBSD investigations. In order to gain insights into the evolution of texture during recrystallization, the contributions from dynamic and static recrystallization were initially separated and the origin of the non-basal orientation of recrystallization nuclei was traced back to several potential nucleation sites within the deformed matrix. Considering the significant role of double-twin band recrystallization in determining the recrystallization texture, this type of recrystallization nucleation was further investigated via quasi-in situ EBSD on a deformed sample, annealed at 400 °C for different annealing times. With progressive annealing, a noticeable trend was observed, in which the basal nuclei gradually diminished and eventually vanished from the annealed microstructure. In contrast, the off-basal nuclei exhibited continuous growth, ultimately becoming the dominant contributors to the recrystallization texture. The study therefore emphasizes the importance of particular nucleation sites that generate favorably oriented off-basal nuclei, which over the course of recrystallization outcompete the neighboring basal-oriented nuclei in terms of growth and thereby dominate the recrystallization texture.

Selective vulnerability of the suprachiasmatic nucleus in progressive Alzheimer’s Disease: A human postmortem study using spatial in‐situ proteomics

AbstractBackgroundAlzheimer’s Disease (AD) patients commonly experience sleep/wake (S/W) disturbances, such as sleep fragmentation and excessive daytime sleepiness. The S/W cycle is controlled by a complex system regulated by a master regulator, the suprachiasmatic nucleus (SCN) that controls wake‐ and sleep‐promoting nuclei. Despite its importance in orchestrating sleep architecture, little is known about the molecular changes that occur in the SCN during the progression of AD and how these changes contribute to S/W disturbances.MethodWe used postmortem brain tissue of 10 controls without AD pathology and 32 subjects with progressive AD stages. Our approach included quantitative neuropathological assessments of AVP and VIP‐expressing neurons in SCN and its adjacent hypothalamic region, the supraoptic nucleus (SON). We also used an in‐situ cell‐specific spatial proteomics platform [GeoMx Digital Spatial Profiling (DSP)] to probe levels of different pathological tau species and proteins commonly dysregulated in AD.ResultPreliminary findings reveal a significant decrease in SCN volume (∼75%) (Fig.1) and a loss of ∼58% AVP neurons and ∼41% VIP neurons in Braak stage (Braak) VI compared to Braak 0. The DSP results indicate that both neurons in the SCN have twice the burden of p‐tau levels as the SON (Fig.2‐right), and neurofibrillary tanglesAdditionally, SCN shows an increase in proteins associated with glia and immune responses (Fig.2‐left). Furthermore, an increase in microglial proteins is observed in the SCN in Braak I (Fig.3‐left). In contrast, the SON displays a milder pattern of protein dysregulation in Braak I (Fig.3‐right), consistent with its lower tau expression observed in histology and DSP.ConclusionSCN is vulnerable to AD pathology even in Braak I, which is characterized by volume loss, increased immune response protein dysregulation, and later neuronal loss, as well as p‐tau pathology. This pattern supports the idea that the SCN plays a role in S/W disturbances observed from early AD stages. Interestingly, its neighboring nucleus, SON, which also has AVP neurons, remained spared, providing opportunities for studies investigating factors related to selective vulnerability. Ongoing studies are addressing changes in the SCN and SON in intermediate AD stages.

Synchronous nuclear division and the role of the cytoskeleton in the multinucleate red alga Griffithsia monilis

Most taxonomic groups of organisms harbor temporarily or permanently multinucleate cells in all or parts of their bodies. Each nucleus in the same cytoplasm responds almost identically to environmental cues, but little is known about the signals that mediate their coordinated division. In this study, we used Griffithsia monilis, a multinucleated giant cell, to investigate how its nuclear division occurs and the role of cytoskeleton in this process. Our results show that nuclear division is exquisitely coordinated and synchronized, but that nuclear division and chloroplast division are not coupled to each other. Microtubules are known to play an important role in synchronized nuclear division in some large multinucleate green algae, and microtubule arrangement is involved in shaping the cytoplasmic domains of each nucleus. However, we found no evidence for the involvement of the cytoskeleton in the synchronized nuclear division or regular nuclear arrangement in G. monilis. Although the nuclei were arranged at very regular intervals, these intervals became irregular during nuclear division, and there was no regular arrangement of actin or microtubules to maintain the spacing between the nuclei. Neither cortical microtubules nor spindle microtubules were physically connected to other neighboring nuclei during nuclear division, suggesting that microtubules are not involved in the coordination of nuclear division in G. monilis.

Shape evolution of nuclei in the region of (A≈30) using covariant density functional theory

Shape evolution of even–even isotopes of Ne, Mg, Si, S, Ar and Ca in the vicinity of [Formula: see text] mass region of the nuclear chart is studied using covariant density functional theory. It will be studied based on finite range NN-interaction force represented by NL3∗ and DD-ME2 and zero finite range NN-interaction force represented by DD-PC1. Both [Formula: see text]Mg and [Formula: see text]Si exhibit shape coexistence and the ground state shape which is found to be both oblate and prolate. The spherical shape is obtained for the Ca isotopes, and for nuclei that have magic neutron numbers [Formula: see text] and 20. The rest of the isotopic chain has only one minimum and alternates between prolate and oblate shapes. Physical properties are calculated at the location of ground state deformation with neutron number ([Formula: see text]) and proton number ([Formula: see text]), such as the binding energy, two-neutron separation energies, proton, neutron and charge radii. In general, a smooth change in these properties is found, except near [Formula: see text] and 20 one can see a sharp change, which reflects the sudden change in the ground state deformation in the neighboring nuclei. A very good agreement is found with the available experimental data, HF and FRDM models

Alpha decay and cluster radioactivity investigation of actinide nuclei

Based on the Unified Fission Model with a Woods–Saxon potential (UFMWS), we have investigated alpha decay and cluster radioactivity of actinide nuclei. To ensure accuracy, we determined the most precise [Formula: see text]-values by comparing the results of four nuclear mass models: the liquid drop model (LDM), the DZ28 model, the WS4 model, and the finite range droplet model (FRDM), which were recently improved using a machine learning algorithm. Among these models, it is found that the improved WS4 (IWS4) provides the most accurate [Formula: see text]-values, enabling the UFMWS model to effectively reproduce experimental alpha and cluster decay half-lives. Consequently, the UFMWS model using IWS4 [Formula: see text]-values was employed to explore various combinations of parent nuclei and alpha particle as well as even–even emitted clusters ranging from Be to Si. The obtained results are consistent with previous study that identified minima in half-lives near corresponding to the doubly magic [Formula: see text]Pb daughter nucleus or its neighboring nuclei. It is found that neutron-deficient parent nuclei generally displayed the shortest half-lives, most of which are within the experimental range. Considering the experimental limitations, cluster decays favorable for measurement in the actinide region were identified. Interestingly, these decays did not involve the most neutron-deficient nuclei.

Acute nicotine abstinence amplifies subjective withdrawal symptoms and threat-evoked fear and anxiety, but not extended amygdala reactivity.

Tobacco smoking imposes a staggering burden on public health, underscoring the urgency of developing a deeper understanding of the processes that maintain addiction. Clinical and experience-sampling data highlight the importance of anxious withdrawal symptoms, but the underlying neurobiology has remained elusive. Mechanistic work in animals implicates the central extended amygdala (EAc)-including the central nucleus of the amygdala and the neighboring bed nucleus of the stria terminalis-but the translational relevance of these discoveries remains unexplored. Here we leveraged a randomized trial design, well-established threat-anticipation paradigm, and multidimensional battery of assessments to understand the consequences of 24-hour nicotine abstinence. The threat-anticipation paradigm had the expected consequences, amplifying subjective distress and arousal, and recruiting the canonical threat-anticipation network. Abstinence increased smoking urges and withdrawal symptoms, and potentiated threat-evoked distress, but had negligible consequences for EAc threat reactivity, raising questions about the translational relevance of prominent animal and human models of addiction. These observations provide a framework for conceptualizing nicotine abstinence and withdrawal, with implications for basic, translational, and clinical science.

Predictions of nuclear charge radii* *Supported by National Natural Science Foundation of China (11905130)

In this study, we improve the relations of the charge-radius difference of two isotopes by considering a term that relates to the proton number and the parity of the neutron number. The correction reduces the root-mean-squared deviation to 0.0041 fm for 651 nuclei with a neutron number larger than 20, in comparison with experimental data compiled in the CR2013 database. The improved relations are combined with local relations consisting of the charge radii of four neighboring nuclei. These combinations also prove to be efficient in describing and predicting nuclear charge radii and can reflect the structure evolutions of nuclei. Our predictions of 2467 unknown nuclear charge radii at competitive accuracy, which are calculated using these two types of relations, are tabulated in the Supplemental Material.

A glucose-sensing mechanism with glucose transporter 1 and pyruvate kinase in the area postrema regulates hepatic glucose production in rats

The area postrema (AP) of the brain is exposed to circulating metabolites and hormones. However, whether AP detects glucose changes to exert biological responses remains unknown. Its neighboring nuclei, the nucleus tractus solitarius (NTS), responds to acute glucose infusion by inhibiting hepatic glucose production, but the mechanism also remains elusive. Herein, we characterized AP and NTS glucose-sensing mechanisms. Infusion of glucose into the AP, like the NTS, of chow rats suppressed glucose production during the pancreatic (basal insulin)-euglycemic clamps. Glucose transporter 1 or pyruvate kinase lentiviral-mediated knockdown in the AP negated AP glucose infusion to lower glucose production, while the glucoregulatory effect of NTS glucose infusion was also negated by knocking down glucose transporter 1 or pyruvate kinase in the NTS. Furthermore, we determined that high-fat (HF) feeding disrupts glucose infusion to lower glucose production in association with a modest reduction in the expression of glucose transporter 1, but not pyruvate kinase, in the AP and NTS. However, pyruvate dehydrogenase activator dichloroacetate infusion into the AP or NTS that enhanced downstream pyruvate metabolism and recapitulated the glucoregulatory effect of glucose in chow rats still failed to lower glucose production in HF rats. We discovered that a glucose transporter 1- and pyruvate kinase-dependent glucose-sensing mechanism in the AP (as well as the NTS) lowers glucose production in chow rats and that HF disrupts the glucose-sensing mechanism that is downstream of pyruvate metabolism in the AP and NTS. These findings highlight the role of AP and NTS in mediating glucose to regulate hepatic glucose production.

Preformation probability and kinematics of cluster emission yielding Pb-daughters* *Supported by the Fundamental Research Grant Scheme (FRGS/1/2019/STG02/UNIMAP/02/2) from the Ministry of Education Malaysia stipulated with the Institute of Engineering Mathematics (IMK) of the Faculty of Applied and Human Sciences UniMAP as the beholder, Science and Engineering Research Board (SERB, CRG/2021/001229), FOSTECT Project (FOSTECT.2019B.04), FAPESP Project (2017/05660-0)

In the present study, the newly established preformation formula is applied for the first time to study the kinematics of the cluster emission from various radioactive nuclei, especially those that decay to the double shell closure Pb nucleus and its neighbors as daughters. The recently proposed universal cluster preformation formula has been established based on the concepts that underscore the influence of mass and charge asymmetry ( and ), cluster mass , and the Q-value, paving the way to quantify the energy contribution during preformation as well as during the tunneling process separately. The cluster-daughter interaction potential is obtained by folding the relativistic mean-field (RMF) densities with the recently developed microscopic R3Y using the NL and the phenomenological M3Y NN potentials to compare their adaptability. The penetration probabilities are calculated from the WKB approximation. With the inclusion of the new preformation probability , the predicted half-lives of the R3Y and M3Y interactions are in good agreement with the experimental data. Furthermore, a careful inspection reflects slight differences in the decay half-lives, which arise from their respective barrier properties. The for systems with double magic shell closure Pb daughter are found to be an order of higher than those with neighboring Pb daughter nuclei. By exploring the contributions of the decay energy, the recoil effect of the daughter nucleus is evaluated, in contrast to several other conjectures. Thus, the centrality of the -value in the decay process is demonstrated and redefined within the preformed cluster-decay model. Additionally, we have introduced a simple and intuitive set of criteria that governs the estimation of recoil energy in the cluster radioactivity.

Dual consistency semi-supervised nuclei detection via global regularization and local adversarial learning

Nuclei detection is a fundamental analytical step in digital histopathology image analysis. Since labeling the centroids for each nucleus in histopathology images is extremely time-consuming, researchers attempt to explore consistency-based approaches for efficient semi-supervised nuclei detection. However, existing methods can only be used for detection on small patches mostly containing one nucleus and contextual information among neighboring nuclei is not considered. On the contrary, using the whole image to achieve nuclei detection in a semi-supervised manner may suffer from a large amount of background noise and thus cannot yield optimal performance. To address these problems, we propose a novel semi-supervised learning method for nuclei detection on a full-size histopathology image via global consistency regularization and local consistency adversarial learning. Specifically, the proposed dual consistency semi-supervised learning can improve the efficiency in inference and learn the context-aware nuclei features by global consistency regularization. Meanwhile, local consistency adversarial learning is introduced to focus on nuclei regions and reinforce the local spatial contiguity of prediction maps. We have evaluated the proposed dual consistency semi-supervised method on public CRCHisto and collected SemiBCN datasets, and the results show that with the synergy of global consistency regularization and local consistency adversarial learning, our method delivers a significant improvement over the state-of-the-art methods.

Germline/soma distinction in Drosophila embryos requires regulators of zygotic genome activation.

In Drosophila melanogaster embryos, somatic versus germline identity is the first cell fate decision. Zygotic genome activation (ZGA) orchestrates regionalized gene expression, imparting specific identity on somatic cells. ZGA begins with a minor wave that commences at nuclear cycle (NC)8 under the guidance of chromatin accessibility factors (Zelda, CLAMP, GAF), followed by the major wave during NC14. By contrast, primordial germ cell (PGC) specification requires maternally deposited and posteriorly anchored germline determinants. This is accomplished by a centrosome coordinated release and sequestration of germ plasm during the precocious cellularization of PGCs in NC10. Here, we report a novel requirement for Zelda and CLAMP during the establishment of the germline/soma distinction. When their activity is compromised, PGC determinants are not properly sequestered, and specification is disrupted. Conversely, the spreading of PGC determinants from the posterior pole adversely influences transcription in the neighboring somatic nuclei. These reciprocal aberrations can be correlated with defects in centrosome duplication/separation that are known to induce inappropriate transmission of the germ plasm. Interestingly, consistent with the ability of bone morphogenetic protein (BMP) signaling to influence specification of embryonic PGCs, reduction in the transcript levels of a BMP family ligand, decapentaplegic (dpp), is exacerbated at the posterior pole.

A new relation for nuclear masses based on the nuclide chain with the same number of neutrons

There are many studies in Odd–Even staggering (OES) of nuclear masses, but the research on nuclear masses by using the systematicness of OES is indeed very few. In this work, we analyze the relationship among the four neighboring nuclei based on the OES of nuclide chain with the same number of neutrons in atomic mass evaluation database (AME2016 database). Our purpose in this paper is to describe an empirical formula with one constant for OES of nuclear masses that can be useful in describing and predicting nuclear masses with mass number [Formula: see text]. With the empirical formula and AME2016 database, the root-mean-square deviation (RMSD) of the nuclei that we have successfully obtained 172[Formula: see text]keV for [Formula: see text] (the RMSD is 140[Formula: see text]keV for [Formula: see text]). This paper also uses Levenberg–Marquart (L-M) neural network approach to study the OES of nuclear masses ([Formula: see text], RMSD [Formula: see text][Formula: see text]keV; [Formula: see text], RMSD [Formula: see text][Formula: see text]keV). The results show that the RMSD of nuclear masses for [Formula: see text] based on neural network approach 30[Formula: see text]keV decreases than that based on empirical formula (the accuracy is increased by about 17%). In addition, the predicted values based on the empirical formula and L-M neural network approach are consistent with the values in AME2020 database, and the difference between our predicted values based on AME2016 database and experimental values measured in recent years is small. These results show that the new relation for nuclear masses has good simplicity, accuracy and reliability. Accurate nuclear mass is helpful to the research of nuclear physics, nuclear technology and astrophysics.

Macroscopic and microscopic description of phase transition in cerium isotopes

The spherical-to-deformed phase transition in cerium isotopes recently suggested to occur between $^{146}\mathrm{Ce}$ and $^{148}\mathrm{Ce}$ has been examined in the framework of the macroscopic algebraic collective model and two microscopic approaches, namely Skyrme-Hartree-Fock $+$ Bardeen-Cooper-Schrieffer (BCS) calculations and the symmetry conserving configuration mixing method with Gogny energy density functionals applied also to the neighboring nuclei along the cerium isotopic chain. Possible spectral signatures of the phase transition are discussed in more details. The microscopic calculations predict octupole softness manifested by rather flat potential energy curves as a function of the octupole deformation parameter ${\ensuremath{\beta}}_{3}$ for $^{146}\mathrm{Ce}$ and $^{148}\mathrm{Ce}$ and shape coexistence characterized by axially symmetric ${0}^{+}$ states, triaxial ${2}^{+}$ bands, and octupole deformation for the lowest ${1}^{\ensuremath{-}}$ states.

Coupled-channel description for mirror mass-11 nuclei compared to shell-model structures

The spectra of mass-11 nuclei are unusual, and so pose a challenge for nuclear-structure theory. Relating to nucleon emission, the set of isobars range from being well-bound (^{11}B,^{11}C) through weakly bound (^{11}Li, ^{11}Be), to being proton unstable (^{11}N,^{11}O). To add complexity, the weakly bound ^{11}Li takes the form of a two-nucleon halo nucleus. A self-consistent approach to understand this set of nuclei is especially important as the mirror pair ^{11}Be-^{11}N exhibit a parity-inverted ground state compared to their neighboring nuclei. Herein, the Multi-Channel Algebraic Scattering method (MCAS) has been used to describe the low excitation spectra of those isobars in terms of nucleon-nucleus clusters. A collective model description of the low-excitation states of the mass-10 mass-10 core nuclei has been used to form the coupled-channel interactions required in the method. For comparison, and to understand the underlying configurations, a shell model approach has been used to obtain those spectra with no-core (0+2+4)hbar omega and (0+2)hbar omega shell-model spaces for the mass 10 and mass 11 nuclei respectively. The results of the calculations suggest the need of a strong coupling in the collective coupled-channel vibrational model. In particular, the strong coupling of the collective 2^+_1 state of ^{10}Be to the valence neutron plays a decisive role in forming the positive parity ground state in ^{11}Be; an effect confirmed by the shell-model results.

Different manifestations of triaxial shapes of the positive and negative parity bands in Os187

The excited states of $^{187}\mathrm{Os}$ have been studied via $^{186}\mathrm{W}(^{4}\mathrm{He},3n)^{187}\mathrm{Os}$ reaction at a beam energy of 36 MeV. The $\ensuremath{\gamma}$ rays were detected using the Indian National Gamma Array at the Variable Energy Cyclotron Centre having seven Compton-suppressed clover high-purity germanium (HPGe) detectors and one low-energy photon spectrometer (LEPS) detector with a digital data acquisition system. The level scheme of $^{187}\mathrm{Os}$ has been extended substantially up to $\ensuremath{\approx}$3.86 MeV of excitation energy and $37/2\phantom{\rule{0.16em}{0ex}}\ensuremath{\hbar}$ of spin with the placement of more than 90 new $\ensuremath{\gamma}$ rays. All known bands have been extended and new band structures have been identified. The results show evidence of triaxial shapes for different configurations of $^{187}\mathrm{Os}$ and different manifestations of nonaxial shape have been observed in the same nucleus. A comparison of the observed band crossing frequency in $^{187}\mathrm{Os}$ with neighboring nuclei gives evidence of a deformed shell gap at $N=110$. The experimental results are well explained using total Routhian surface calculations.

Alignment effects in the medium-spin level structure of Se78

The excited states of $^{78}\mathrm{Se}$ were populated using the $^{76}\mathrm{Ge}(\ensuremath{\alpha},2n)$ fusion evaporation reaction. The deexcited gamma rays were detected using the Indian National Gamma Array (INGA) spectrometer comprising clover and low-energy photon spectrometer (LEPS) detectors. The ground state band of $^{78}\mathrm{Se}$ has been extended up to ${E}_{x}$ = 8.5 MeV and $J$ = $16\ensuremath{\hbar}$; this excitation regime is very close to the $\ensuremath{\pi}(1{g}_{9/2}^{2})$ crossing frequency. Several newly observed in-band and intraband transitions belonging to the other bands of $^{78}\mathrm{Se}$ have also been placed in the level scheme based on their coincidence relationships. From the newly identified $E1$ transitions, an enhancement in the $B(E1)$/$B(E2)$ values with spin has been observed which indicates the onset of octupole correlations in the band structure built on the ${3}^{\ensuremath{-}}$, 2508-keV state. Persistence of triaxial shape up to the highest observed spin of the ground state band has been observed and the feature of successive $1{g}_{9/2}^{2}$ quasiparticle alignments due to protons and neutrons has been unveiled. The consequences arising due to the occurrence of the neutron $1{g}_{9/2}$ quasiparticle alignments in the other observed correlated band structures are also presented. The results are interpreted in terms of total Routhian surface (TRS) calculations and the level structure systematic of the neighboring nuclei.

Trends in the Structure of Nuclei near 100Sn

Inevitable progress has been achieved in recent years regarding the available data on the structure of 100Sn and neighboring nuclei. Updated nuclear structure data in the region is presented using selected examples. State-of-the-art experimental techniques involving stable and radioactive beam facilities have enabled access to those exotic nuclei. The analysis of experimental data has established the shell structure and its evolution towards N = Z = 50 of the number of neutrons, N, and the atomic number, Z, seniority conservation and proton–neutron interaction in the g9/2 orbit, the super-allowed Gamow–Teller decay of 100Sn, masses and half-lives along the rapid neutron-capture process (r-process) path and super-allowed α decay beyond 100Sn. The status of theoretical approaches in shell model and mean-field investigations are discussed and their predictive power assessed. The calculated systematics of high-spin states for N = 50 isotopes including the 5− state and N = Z nuclei in the g9/2 orbit is presented for the first time.