Residual Nuclei Research Articles

白内障超声乳化术后前房核块残留1例

晶状体核块或晶状体碎片残留常发生于白内障超声乳化术中出现后囊破裂的患者中；手术中顺利，无后囊破裂的患者中，术后晶状体核块残留发生很少。术后残留晶状体核块可以继发眼压升高、角膜水肿、葡萄膜炎和其它并发症，这种并发症可能导致视功能障碍。本文报道一例Ⅳ级硬核年龄相关性白内障患者，白内障超声乳化及人工晶状体植入手术过程顺利，术中没有发生后囊破裂等并发症的患者，术后1周发现前房晶状体核块残留，导致角膜水肿，经二次手术行前房冲洗术取出残留晶状体核块，术后恢复良好。 Residual lens nucleus or lens fragments often occur in patients with posterior capsule rupture during phacoemulsification, but rarely in patients without posterior capsule rupture. Intraocular pressure, corneal edema, uveitis and other complications can be secondary to residual lens nucleus after surgery, which may lead to visual dysfunction. This paper reported a case of age-related cataract with grade IV hard nucleus. Phacoemulsification and intraocular lens implantation was successfully performed. Posterior capsule rupture didn’t occur during the operation. One week after the operation, a residual lens nucleus was found in the anterior chamber, which led to corneal edema. The residual lens nucleus was removed by anterior chamber irrigation and recovered well.

The Study of Neutron Induced Reaction on Manganese Reaction Cross-Section at Intermediate Energy

The general neutron induced reaction cross sections with the projectile neutron energy are being studied. As a result of this, the compound nucleus is formed through de-excitation of the selected nuclei by emitted particles γ and 2n with the reaction cross section at intermediate energy. The production of residual nuclide by neutron induced reaction on the selected nuclei has been investigated by using computer code projection angular-momentum coupled evaporation Monte Carlo code (PACE4). Dependence of Reaction Cross Section for Projectile Neutron with Different K Values on Target 55Mn in the Energy Range (0.5 - 3.42) Mev and Dependence of Reaction Cross Section for Projectile Neutron with Different K Values on 55Mn Target in the Energy Range (11.5 - 38.5) Mev. Then, the theoretical estimated value compared with the Experimental value the data which obtained from International Atomic and Energy Agency, Exchange format. Results show us the reaction cross section vs energy of projectile neutron with target nucleus Manganese and the emitted particles were γ and 2n respectively with new residual nuclei, i.e. 56Mn and 54Mn, in addition to this the best fit K values are 10 and 8 for each channels respectively. Finally the level density parameter is the dominant parameter that can influence the reaction cross section from the outcome of this software by varying with free constant parameter (K). i.e., 8, 10 and 12.

Measurement of radioactive residual nuclides induced in Cu target by 80.5 MeV/u carbon ions

Radioactive residual nuclides, which are usually closely related to radiation protection and personnel safety, will be generated when target materials are irradiated by high energy particles. Based on different nuclear reaction models, Monte Carlo code is a usual method to obtain residual nuclide production. The simulation accuracy needs to be evaluated by experimental data. In this paper, an irradiation experiment of thin copper target irradiated by <sup>12</sup>C<sup>6+</sup> particles with energy of 80.5 MeV/u is carried out. The radioactivities and cross-sections of 18 radioactive residual nuclides are obtained by gamma spectrometry analysis. Compared with the Monte Carlo simulation by PHITS, the results show that the spallation model of PHITS has a high reliability in estimating the types of radioactive residual nuclei, and it could be optimized in the aspect of the absolute yield.

The impact of indoor thermal stratification on the dispersion of human speech droplets

Exhaled jets from an infected person are found to be locked at a certain height when thermal stratification exists in rooms, causing a potential high risk of disease transmission. This work is focused on the theoretical analysis of the dynamic characteristics of human speech droplets and the residual droplet nuclei in both thermally uniform and stratified environments. Results show that most droplets generated from human speaking can totally evaporate or deposit to the ground within 1.5-2m. For small droplets of<80μm, thermal stratification shows a more significant impact on their residues. The lock-up height of the droplet nuclei is a function of droplet size and the temperature gradient, and within this lock-up layer, these droplet nuclei can travel a long distance, much more than 2m. For medium droplets of 80-180μm, thermal stratification can weaken the evaporation and accelerate the deposition processes, equivalent to a higher relative humidity (RH). Accordingly, more droplets can deposit to the ground, reducing the exposure to large droplets in close proximity to the source. Large droplets of>180μm show no dependence on stratification and RH. These findings can have implications for developing effective engineering methods to limit the spread of infectious disease.

Hyperfine spectroscopy in a quantum-limited spectrometer.

We report measurements of electron-spin-echo envelope modulation (ESEEM) performed at millikelvin temperatures in a custom-built high-sensitivity spectrometer based on superconducting micro-resonators. The high quality factor and small mode volume (down to 0.2 pL) of the resonator allow us to probe a small number of spins, down to . We measure two-pulse ESEEM on two systems: erbium ions coupled to nuclei in a natural-abundance crystal and bismuth donors coupled to residual nuclei in a silicon substrate that was isotopically enriched in the isotope. We also measure three- and five-pulse ESEEM for the bismuth donors in silicon. Quantitative agreement is obtained for both the hyperfine coupling strength of proximal nuclei and the nuclear-spin concentration.

Investigation of Formation of Residual Nuclei from 209Bi by Reactions with 660 MeV Protons and Comparison with MCNP Simulation Results

Investigation of Formation of Residual Nuclei from 209Bi by Reactions with 660 MeV Protons and Comparison with MCNP Simulation Results

Halo-like structure in 7He nucleus

A study of the neutron structure of the ground state of 7He has been performed by means of registration and analysis of the decay channels of the residual nuclei following absorption of stopped pions. In particular, the reaction 9Be ()X have been investigated where X denotes any system with five neutrons and two protons – the constituencies of a 7He nucleus. It was shown that the structure of 7He is determined by correlations of two neutrons in the states 6He (0+), 6He (2+) and one neutron in the shell p3/2. The 4He+3n structure is not manifested in the ground state of 7He. The obtained results are consistent with the known data on considerable mixture of configurations “6He in its ground and first excited states plus a neutron” in the ground state of 7He. Comparison of the diffraction components of the differential cross-sections of the charge-exchange reactions (t, 3He) measured on 6Li and 7Li allowed extracting the radius of particle-unstable nucleus 7He. The latter occurred to be approximately equal to those of 6He and 8He. The obtained result indicates to existence of the halo-like structure in 7He.

Evaluation of Pseudorandom Sonications for Reducing Cavitation With a Clinical Neurosurgery HIFU Device.

Transcranial high-intensity focused ultrasound is used in clinics for treating essential tremor (ET) and proposed for many other brain disorders. This promising treatment modality requires high energy resulting eventually in undesired cavitation and potential side effects. The goals of the present work were: 1) to evaluate the potential increase of the cavitation threshold using pseudorandom gated sonications and 2) to assess the heating capabilities with such sonications. The experiments were performed with the transcranial magnetic resonance (MR)-compatible ExAblate Neuro system (InSightec, Haifa, Israel) operating at a frequency of 670 kHz, either in continuous wave (CW) or with pseudorandom gated sonications of 50% duty cycle. Cavitation activity with the two types of sonications was compared using chemical dosimetry of hydroxyl radical production at the focus of the transducer, after propagation in water or through a human skull. Heating trials were performed in a hydrogel tissue-mimicking material embedded in a human skull to mimic a clinical situation. The temperature was measured by MR-thermometry when focusing at the geometrical focus and steering off focus up to 15 mm. Compared with CW sonications, the use of gated sonication did not affect the efficiency (60%) nor the steering abilities of the transducer. After propagation through a human skull, gated sonication required a higher pressure level (10 MPa) to initiate cavitation as compared with CW (5.8 MPa). Moreover, at equivalent acoustic power above the cavitation threshold, the level of cavitation activity initiated with gated sonications was much lower with gated sonication than with continuous sonications, almost half after propagation through water and one-third after propagation through a skull. This lowered cavitation activity may be attributed to a breaking of the dynamic of the bubbles moving from monochromatic to more broadband sonications and to the removal of residual cavitation nuclei between pulses with gated sonications. The heating capability was not affected by the gated sonications, and similar temperature increases were reached at focus with both types of sonications when sonicating at equivalent acoustic power, both in water or after propagation through a human skull (+15 °C at 325 W for 10 s). These data, acquired with a clinical system, suggest that gated sonication could be an alternative to continuous sonications when cavitation onset is an issue.

Lifetimes of core-excited states in semi-magic ^{95}mathrm {Rh}

Lifetimes of negative-parity states have been determined in the neutron deficient semi-magic (N = 50) nucleus ^{95}mathrm {Rh}. The fusion-evaporation reaction ^{58}Ni(^{40}Ca, 3p) was used to populate high-spin states in ^{95}mathrm {Rh} at the Grand Accélérateur National d’Ions Lourds (GANIL) accelerator facility. The results were obtained using the Doppler Shift Attenuation Method (DSAM) based on the Doppler broadened line shapes produced during the slowing down process of the residual nuclei in a thick 6;mathrm {mg/cm}^2 metallic target. B(M1) and B(E2) reduced transition strengths are compared with predictions from large-scale shell-model calculations.

Experimental study of (p, 2p) reactions at 392 MeV on 12C, 16O, 40Ca and 208Pb nuclei leading to low-lying states of residual nuclei

Abstract We have measured the differential cross-sections and analyzing powers for ($p,2p$) reactions at an incident energy of 392 MeV on $^{12}$C, $^{16}$O, $^{40}$Ca, and $^{208}$Pb nuclei, leading to discrete states of the residual nuclei. The data are compared with two kinds of distorted-wave impulse approximation (DWIA) calculations, a standard calculation using a global optical potential and a calculation using wave functions generated in a relativistic Hartree model. The spectroscopic factors deduced from these two calculations agree with those determined in ($e,e'p$) studies mostly within 15% in the case of the lighter three target nuclei. However, those for the $^{208}$Pb target are overestimated compared with the ($e,e'p$) results. In the heavy target case, the DWIA results are very sensitive to the radius parameter of the bound-state potential and thus a careful treatment is required. Regarding the analyzing powers of the present measurement, we confirmed that the $j$-dependence is sufficient for practical spectroscopic use.

The Inner Annulus Fibrosus Encroaches on the Nucleus Pulposus in the Injured Mouse Tail Intervertebral Disc.

The aim was to identify the source of cells within the center of the abnormal fibrocartilage tissue of the degenerative intervertebral disc after injury. Cross-breeding of mice with an inducible type II promoter collagen construct (Col2CreER) to Rosa26-TdTomato mice has been shown to result in Cre-recombinase activity and Tomato expression in inner annulus fibrosus cells after tamoxifen injection. To investigate the role of the inner annulus fibrosus in the intervertebral disc injury response, tail intervertebral discs of Col2CreER/tdTomato mice were punctured with a needle and examined 1-4 wks after injury. N-cadherin was examined by immunostaining. After the injury, the fibrocartilage in the degenerative intervertebral disc consisted of residual diseased nucleus pulposus cells and encroaching inner annulus fibrosus cells. The residual nucleus pulposus cells had lost their epithelial cell-like morphology and instead became oval shaped, with reduced adhesion to neighboring nucleus pulposus cells. This change in cellular morphology coincided with a loss of N-cadherin, which contributes to maintenance of healthy nucleus pulposus cell morphology. As expected, injured tail intervertebral discs showed reduced compressive properties as determined by biomechanical assessments. The cellular composition of the degenerative intervertebral disc has been defined here, which is an important step in developing future treatments.

The diet of otters (Lutra lutra) on the Agri river system, one of the most important presence sites in Italy: a molecular approach.

BackgroundThe Eurasian otter (Lutra lutra) underwent a strong decline in large areas of the Central-Western part of its distribution range, during the second half of the twentieth century. In Italy, only residual fragmented nuclei survive in the Central-Southern part of the peninsula. Nowadays, the otter is one of the most endangered mammals in Italy, and increasing the knowledge about the ecology of this species is a key step in defining fitting management strategies. Here we provide information about the diet of otter on the Agri river system, one of the most important presence sites in Italy, to understand both the species’ food requirements and the impact on fish communities.MethodsDNA metabarcoding and High Throughput Sequencing were used on DNA extracted from spraints. We amplified DNA with a primer set for vertebrates, focusing efforts on the bulk of the otter’s diet (fishes and amphibians).ResultsOur findings showed that the diet of the otter was dominated by cyprinids (97.77%, and 99.14% of fishes), while amphibians represented 0.85% of the sequences analyzed. Results are in general accordance with previous studies based on morphological characterization; however, molecular analyses allow the resolving of some morphological uncertainties. Although the study area offers a very wide range of available prey, the diet of the otters shows marked selectivity. We highlighted a variation in prey consumed, in accordance with the typology of water system (i.e., river, lake, tributary). Some of the preys found in the diet were alien species introduced by man for sport fishing. Our findings could help define strategies useful for the conservation of the otter population in Southern Italy, suggesting management actions directed at avoiding fish community alterations through illegal stockings without severe controls on their taxonomic status. These introductions could result in a general reduction in the diversity of the otter’s preys, affecting its predatory behavior.

Evaluation of the activation of brass apertures in proton therapy using gamma-ray spectrometry and Monte Carlo simulations

Collimating apertures are used in proton therapy to laterally conform treatment fields to the target volume. While this is a standard technique in passive spreading treatment heads, patient-specific apertures can supplement pencil-beam scanning (PBS) techniques to sharpen the lateral dose fall-off. A radiation protection issue is that proton-induced nuclear reactions can lead to the formation of radionuclides in the apertures. In the experiments of the current study, cylindrical, thick brass targets were irradiated with quasi-monoenergetic proton fields of 100.0 MeV and of 226.7 MeV in PBS mode. The radioactivation of these two brass samples was characterised with a low-level gamma-ray spectrometer. The activation products were scored in a Monte Carlo simulation, too, and compared with the experimental activities. For the high-energy field, 63Zn, 60Cu, and 61Cu were the most important short-lived isotopes regarding the measured specific activity. After irradiation with the 100.0 MeV field, 62Cu, 63Zn, and 60Cu had the highest activity. Regarding long-lived isotopes, which determine the storage time of the used apertures, the isotopes 57Co, 65Zn, 54Mn, 56Co had the largest contribution to the activity. The relative difference of activities between simulation and experiment was typically between 10%–20% for short-lived nuclides and were up to a factor of five larger for long-lived nuclides. Summarising experiments and simulations for both incident proton energies, 62Cu was the most important detected residual nucleus regardless if specific activity or equivalent dose is considered.

Inclusion of sequential emission into the most probable fragmentation approach (Los Alamos model) and its validation

A new version of the Los Alamos (LA) model, based on more physical considerations than the previous versions by taking into account the sequential emission of prompt neutrons, is proposed. A residual temperature distribution for each emission sequence P $$_{\mathrm {k}}$$ (T) is considered, so that this new version can provide the prompt neutron spectrum in the center-of-mass and laboratory frames of each neutron successively emitted from the light and heavy fragment. The LA model with sequential emission is applied on 15 fission cases which were not included in the 49 cases used in the elaboration of the systematics of different quantities of residual nuclei, on which the general form of $$\hbox {P}_{\mathrm {k}}$$ (T) is based. The good description of experimental prompt neutron spectrum data of these fission cases by the model results constitutes a relevant validation of the LA model with sequential emission. Systematic behaviours of the average energies (in the center-of-mass and laboratory frames) provided by this model for each neutron sequentially emitted, are also emphasized.

Clinical study of single-level cervical disc herniation treated by full-endoscopic decompression via anterior transcorporeal approach

To investigate the clinical feasibility of full-endoscopic decompression for the treatment of single-level cervical disc herniation via anterior transcorporeal approach. According to the inclusion and exclusion criteria, 21 patients with cervical disc herniation who received full-endoscopic decompression via anterior transcorporeal approach between September 2014 and March 2016 were retrospectively analyzed. There were 12 males and 9 females with an age ranged from 32 to 65 years, with an average of 48.5 years. The duration of symptoms ranged from 6 to 18 weeks, with an average of 10.5 weeks. According to the Nurick grading of spinal cord symptoms, there were 2 cases with grade 1, 7 cases with grade 2, and 12 cases with grade 3. Operative segment was C 3, 4 in 2 cases, C 4, 5 in 8 cases, C 5, 6 in 9 cases, and C 6, 7 in 2 cases. The operation time and related complications were recorded. The central vertical height of the vertebral body and the diseased segment space were measured on the cervical X-ray film. The neck and shoulder pain were evaluated by visual analogue scale (VAS) score; Japanese Orthopaedic Association (JOA) score was used to evaluate the improvement of neurological function in patients. The MRI of cervical spine was reexamined at 3 months after operation, and the CT of cervical spine was reexamined at 12 months after operation. The decompression of spinal cord and the healing of bone canal in the vertebral body were further evaluated. Full-endoscopic decompression via anterior transcorporeal approach were achieved at all 21 patients. The operation time was 85-135 minutes, with an average of 96.5 minutes. All patients were followed up 24-27 months, with an average of 24.5 months. There was no complication such as residual nucleus pulposus, spinal cord injury, large esophageal vessels injury, pleural effusion, endplate collapse, intraspinal hematoma, cervical spine instability, protrusion of disc in the same segment, or kyphosis. Both VAS scores of neck and shoulder pain and JOA scores were significantly improved at 12 months after operation ( P<0.05). At 3 months after operation, it was confirmed by the cervical MRI that neural decompression was sufficient and the abnormal signal was also degraded in the patients with intramedullary high signal at T2-weighted image. The cervical CT showed that bone healing were achieved in the surgical vertebral bodies of all patients at 12 months after operation. At 24 months after operation, the central vertical height of the diseased segment space significantly decreased compared with preoperative one ( t=2.043, P=0.035); but there was no significant difference in the central vertical height of the vertebral body between pre- and post-operation ( t=0.881, P=0.421). Full-endoscopic decompression via anterior transcorporeal approach, integrating the advantages of the endoscopic surgery and the transcorporeal approach, provide an ideal and thorough decompression of the ventral spinal cord with satisfactory clinical and radiographic results.

Nuclear level density of 69Zn from gamma gated particle spectrum and its implication on 68Zn(n, γ)69Zn capture cross section

Evaporated α-spectra have been measured in coincidence with low energy discrete γ-rays from residual nucleus 68Zn populated by αn evaporation from compound nucleus 73Ge produced in the reaction 64Ni(9Be,αn)68Zn at E(9Be) = 30 MeV. Low energy γ-gated α-particle spectra, for the first time, have been used to extract the nuclear level density (NLD) for the intermediate 69Zn nucleus in the excitation energy range of E ≈ 4-20 MeV. The slope of present NLD data as a function of excitation energy for 69Zn matches nicely with the slope determined from RIPL estimates for NLD at low energies and the NLD from neutron resonance data at neutron separation energy Sn. The extracted inverse NLD parameter (k = A/a˜) has been used to determine the nuclear level density parameter value a at neutron separation energy Sn for 69Zn. The cross section of 68Zn(n,γ) capture reaction as a function of neutron energy is then estimated employing the derived a(Sn) in the reaction code TALYS. It is found that the estimated neutron capture cross section agrees well with the available experimental data without any normalization. The present result indicates that experimentally derived nuclear level density parameter can constrain the statistical model description of astrophysical capture cross section and optimize the uncertainties associated with astrophysical reaction rate.

ETV2-null porcine embryos survive to post-implantation following incomplete enucleation

Blind enucleation is used in porcine somatic cell nuclear transfer (SCNT) to remove the metaphase II (MII) spindle from the oocyte. Deviation of the MII spindle location, however, leads to incomplete enucleation (IE). Here, we report that the rate of complete enucleation (CE) using the blind method was 80.2 ± 1.7%, although this significantly increased when the polar body-MII deviation was minimized (≦45°). While it is established that IE embryos will not survive to full term, the effect of IE on early stage development is unknown. We have previously demonstrated in mice and pigs that ETV2 deletion results in embryonic lethality due to the lack of hematoendothelial lineages. We observed that ETV2-null cloned embryos derived from blindly and incompletely enucleated oocytes had both WT and mutant sequences at E18 and, using FISH analysis, we observed triploidy. We also compared SCNT embryos generated from either CE or intentionally IE oocytes using the spindle viewer system. We observed a higher in vitro blastocyst rate in the IE versus the CE-SCNT embryos (31.9 ± 3.2% vs 21.0 ± 2.1%). Based on known processes in normal fertilization, we infer that the IE-SCNT embryos extruded the haploid second PB after fusion with donor fibroblasts and formed a near-triploid aneuploid nucleus in each blastomere. These studies demonstrate the peri-implantation survival of residual haploid nuclei following IE and emphasize the need for complete enucleation especially for the analysis of SCNT embryos in the peri-implantation stage and will, further, impact the field of reverse xenotransplantation.

Cross Section Measurements of (n,p) Reactions on Ge Isotopes

The 72,73Ge(n,p)72,73Ga reaction cross sections were measured at the 5.5MV HV Tandem accelerator of NCSR “Demokritos”, at neutron energies 17.7 and 19.3 MeV by using the activation method. The contamination from the (n,d) and (n,np) reactions on 73Ge and 74 Ge, leading to the 72Ge and 73Ge residual nuclei, respectively, has been taken into account, implementing the corresponding cross sections from TENDL-2017. A systematic investigation of the isotopic effect on all Ge isotopes is also presented, from threshold up to 20MeV, using the present data along with existing data in literature

New insights into the memory effect on the crystallization behavior of poly(phenylene sulfide)

In this article, the melt and crystallization kinetics of poly(phenylene sulfide) (PPS) powder was studied by differential scanning calorimetry (DSC), fourier transform infrared spectroscopy (FTIR) and polarized optical microscopy (POM). It is found that the folded-chain crystals of PPS (melting point at 281 °C) could be erased at about 350 °C, while the equilibrium melting point of extended-chain crystals (melting point at 295 °C) is 370 °C. Although the residual nuclei could be eliminated completely at 370 °C, the spherulite growth rate of PPS during crystallization keeps accelerating with the increasing melting relaxation time, resulting from the transformation of the lamellae and the amorphous cluster to an ordered structure with low entanglement density. Furthermore, due to the restricted chain mobility for the semi-flexible PPS, this unique memory effect would survive in the whole manufacturing process, resulting in the varying results from different researches and the significant influence on the processability and performance of PPS products.

Charge Exchange Reactions on Low-Energy Particle Beams

Charge exchange reactions on light and heavy ion beams are of interest in the production of new isotopes, and for studying the properties of radioactive and stable atomic nuclei. A charge exchange reaction (3He, t) has advantages over other types of reactions, due to much easier identification of charged particles t. The cross sections of reactions on 3He reach hundreds of mbarn at an energy of the bombarding beam near the Coulomb barrier. These reactions result in excitation of the isobar analog and other single particle states in residual nuclei.