Superallowed α Decay to Doubly Magic

We report the first observation of the ^{108}Xe→^{104}Te→^{100}Sn α-decay chain. The α emitters, ^{108}Xe [E_{α}=4.4(2) MeV, T_{1/2}=58_{-23}^{+106} µs] and ^{104}Te [E_{α}=4.9(2) MeV, T_{1/2}<18 ns], decaying into doubly magic ^{100}Sn were produced using a fusion-evaporation reaction ^{54}Fe(^{58}Ni,4n)^{108}Xe, and identified with a recoil mass separator and an implantation-decay correlation technique. This is the first time α radioactivity has been observed to a heavy self-conjugate nucleus. A previous benchmark for study of this fundamental decay mode has been the decay of ^{212}Po into doubly magic ^{208}Pb. Enhanced proton-neutron interactions in the N=Z parent nuclei may result in superallowed α decays with reduced α-decay widths significantly greater than that for ^{212}Po. From the decay chain, we deduce that the α-reduced width for ^{108}Xe or ^{104}Te is more than a factor of 5 larger than that for ^{212}Po.

Evaluation of chromogenic factor IX assays by automated protocols.

INTRODUCTION: Chromogenic substrate assays (CSA) to measure Factor IX (FIX) have recently become commercially available. However, information on their performance characteristics and use in diagnostic haemostasis laboratories remains limited. AIM: To evaluate the Hyphen Biomed (Hyphen) and Rossix FIX CSAs on fully automated coagulation analysers and compare them to the FIX one-stage assay (OSA). This study was conducted in a tertiary referral haemostasis laboratory associated with a haemophilia treatment centre. METHODS: Automated CSA protocols were adapted to the Sysmex CS2500 (CS2500) and Diagnostica Stago STA-R (STA-R) analysers. Samples assayed were from healthy volunteers, haemophilia B patients and FIX deficient plasma spiked with either plasma derived, recombinant or extended half-life FIX products. RESULTS: Reference intervals for Hyphen and Rossix assays were 73 IU/dL to 164 IU/dL and 73 IU/dL to 168 IU/dL, respectively, on the CS2500 analyser; and 84 IU/dL to 165 IU/dL for the Rossix assay on the STA-R. Repeatability across all method/analyser combinations resulted in CVs ranging from 0.8% to 5.4%. Between run reproducibility gave CVs <6.7% for all method/analyser combinations. In spiked samples, FIX recoveries were mostly within an acceptable limit of 100 ± 25% for BeneFIX® , Rixubis® and Alprolix® with some differences between CSAs. CONCLUSION: Both commercial factor FIX CSA kits can be adapted for Stago and Sysmex automated coagulation analysers. Reagent cost and workflow practices will need to be considered. These assays are potentially more consistent than OSA in measurement of replacement FIX products in haemophilia B patients.

Decay and Fission Hindrance of Two- and Four-Quasiparticle K Isomers in

Two isomers decaying by electromagnetic transitions with half-lives of 4.7(1.1) and 247(73) µs have been discovered in the heavy ^{254}Rf nucleus. The observation of the shorter-lived isomer was made possible by a novel application of a digital data acquisition system. The isomers were interpreted as the K^{π}=8^{-}, ν^{2}(7/2^{+}[624],9/2^{-}[734]) two-quasineutron and the K^{π}=16^{+}, 8^{-}ν^{2}(7/2^{+}[624],9/2^{-}[734])⊗8^{-}π^{2}(7/2^{-}[514],9/2^{+}[624]) four-quasiparticle configurations, respectively. Surprisingly, the lifetime of the two-quasiparticle isomer is more than 4 orders of magnitude shorter than what has been observed for analogous isomers in the lighter N=150 isotones. The four-quasiparticle isomer is longer lived than the ^{254}Rf ground state that decays exclusively by spontaneous fission with a half-life of 23.2(1.1) µs. The absence of sizable fission branches from either of the isomers implies unprecedented fission hindrance relative to the ground state.

Measurement of the survival probabilities for hot fusion reactions.

We have studied the fission-neutron emission competition in highly excited (274)Hs (Z=108) (where the fission barrier is due to shell effects) formed by a hot fusion reaction. Matching cross bombardments ((26)Mg+(248)Cm and (25)Mg+(248)Cm) were used to identify the properties of first chance fission of (274)Hs. A Harding-Farley analysis of the fission neutrons emitted in the (25)Mg,26+(248)Cm was performed to identify the prescission and postscission components of the neutron multiplicities in each system. (Γn/Γt) for the first chance fission of (274)Hs (E*=63 MeV) is 0.89±0.13; i.e., ∼90% of the highly excited nuclei survive. The high value of that survival probability is due to dissipative effects during deexcitation. A proper description of the survival probabilities of excited superheavy nuclei formed in hot fusion reactions requires consideration of both dynamic and static (shell-related) effects.

Fission barrier of superheavy nuclei and persistence of shell effects at high spin: cases of 254No and 220Th.

We report on the first measurement of the fission barrier height in a heavy shell-stabilized nucleus. The fission barrier height of 254No is measured to be Bf=6.0±0.5 MeV at spin 15ℏ and, by extrapolation, Bf=6.6±0.9 MeV at spin 0ℏ. This information is deduced from the measured distribution of entry points in the excitation energy versus spin plane. The same measurement is performed for 220Th and only a lower limit of the fission barrier height can be determined: Bf(I)>8 MeV. Comparisons with theoretical fission barriers test theories that predict properties of superheavy elements.

Performance evaluation of the Abbott CELL-DYN Emerald for use as a bench-top analyzer in a research setting.

INTRODUCTION: The CELL-DYN Emerald is a compact bench-top hematology analyzer that can be used for a three-part white cell differential analysis. To determine its utility for analysis of human and mouse samples, we evaluated this machine against the larger CELL-DYN Sapphire and Sysmex XT2000iV hematology analyzers. METHODS: 120 human (normal and abnormal) and 30 mouse (normal and abnormal) samples were analyzed on both the CELL-DYN Emerald and CELL-DYN Sapphire or Sysmex XT2000iV analyzers. For mouse samples, the CELL-DYN Emerald analyzer required manual recalibration based on the histogram populations. RESULTS: Analysis of the CELL-DYN Emerald showed excellent precision, within accepted ranges (white cell count CV% = 2.09%; hemoglobin CV% = 1.68%; platelets CV% = 4.13%). Linearity was excellent (R² ≥ 0.99), carryover was minimal (<1%), and overall interinstrument agreement was acceptable for both human and mouse samples. Comparison between the CELL-DYN Emerald and Sapphire analyzers for human samples or Sysmex XT2000iV analyzer for mouse samples showed excellent correlation for all parameters. CONCLUSION: The CELL-DYN Emerald was generally comparable to the larger reference analyzer for both human and mouse samples. It would be suitable for use in satellite research laboratories or as a backup system in larger laboratories.

The use of FEIBA® in the correction of coagulation abnormalities induced by dabigatran.

INTRODUCTION: Studies have shown dabigatran to be an effective anticoagulant with an acceptable bleeding profile. None the less, these patients do suffer from bleeding complications. Unfortunately, there are currently no direct reversal agents to dabigatran or established guidelines on the management of bleeding in these circumstances. METHODS: We examined the effects on thrombin generation parameters, after ex-vivo spiking the plasma of patients on dabigatran (n = 8) with FEIBA(®). These parameters were measured using the calibrated automated thrombography (CAT) machine. RESULTS: In our study, we showed the ability of FEIBA(®) to improve the abnormal thrombin generation parameters caused by dabigatran in these patients. CONCLUSION: This provides evidence, lacking in the literature, that this agent may be able to provide haemostatic support in situations where dabigatran induced coagulopathy exists.

Wound bed preparation from a clinical perspective.

Wound bed preparation has been performed for over two decades, and the concept is well accepted. The 'TIME' acronym, consisting of tissue debridement, infection or inflammation, moisture balance and edge effect, has assisted clinicians systematically in wound assessment and management. While the focus has usually been concentrated around the wound, the evolving concept of wound bed preparation promotes the treatment of the patient as a whole. This article discusses wound bed preparation and its clinical management components along with the principles of advanced wound care management at the present time. Management of tissue necrosis can be tailored according to the wound and local expertise. It ranges from simple to modern techniques like wet to dry dressing, enzymatic, biological and surgical debridement. Restoration of the bacterial balance is also an important element in managing chronic wounds that are critically colonized. Achieving a balance moist wound will hasten healing and correct biochemical imbalance by removing the excessive enzymes and growth factors. This can be achieved will multitude of dressing materials. The negative pressure wound therapy being one of the great breakthroughs. The progress and understanding on scientific basis of the wound bed preparation over the last two decades are discussed further in this article in the clinical perspectives.

Shell-structure and pairing interaction in superheavy nuclei: rotational properties of the z=104 nucleus (256)rf.

The rotational band structure of the Z=104 nucleus (256)Rf has been observed up to a tentative spin of 20ℏ using state-of-the-art γ-ray spectroscopic techniques. This represents the first such measurement in a superheavy nucleus whose stability is entirely derived from the shell-correction energy. The observed rotational properties are compared to those of neighboring nuclei and it is shown that the kinematic and dynamic moments of inertia are sensitive to the underlying single-particle shell structure and the specific location of high-j orbitals. The moments of inertia therefore provide a sensitive test of shell structure and pairing in superheavy nuclei which is essential to ensure the validity of contemporary nuclear models in this mass region. The data obtained show that there is no deformed shell gap at Z=104, which is predicted in a number of current self-consistent mean-field models.

A prospective, randomised, double-blinded trial to study the efficacy of topical tocotrienol in the prevention of hypertrophic scars.

BACKGROUND: Despite widespread beliefs regarding the use of topical tocotrienol in the prevention of hypertrophic scars, there is very little evidence from well controlled and randomised clinical trials to justify its benefits for surgical scars. OBJECTIVE: This study was conducted to evaluate the efficacy of topical tocotrienol in preventing the development of hypertrophic scars. METHODS: A prospective, randomised, double-blinded study was performed on 122 patients with recently healed (<2 weeks) surgical scars, who were randomised into either a treatment group with 5% topical tocotrienol or a placebo group. The patients were required to apply the preparation to their scars twice a day for 6 weeks starting at 2 weeks after surgery. Assessments of the scars were performed at weeks 0, 2, 6 and 16 following the onset of topical application using three methods: a clinical assessment using the Patient and Observer Scar Assessment Scale (POSAS), a photographic scar assessment by two independent assessors using a visual analogue scale and laser Doppler imaging (LDI). Data analysis was performed on 85 patients (tocotrienol group: 45 patients; placebo group: 40 patients), who had completed four assessments. RESULTS: There was no statistically significant difference in scar parameters between the tocotrienol and the placebo groups in the POSAS, photographic scar assessment or mean flux of LDI (p>0.05) categories. The mean LDI flux showed a decreasing trend over time, which was positively correlated with vascularity (correlation coefficient=0.325, p=0.008) and total scores (correlation coefficient=0.248, p=0.034) of the observer scar assessment scale on week 0. No significant adverse effect was observed. CONCLUSIONS: Twice-daily application of 5% topical tocotrienol had no significant effect on the appearance and vascularity of scars over 4 months post-surgery. LDI has a promising role as a scar assessment tool.

Dried irradiated human amniotic membrane as a biological dressing for facial burns--a 7-year case series.

BACKGROUND: Facial burns are common and have a significant impact on patient function and psychosocial well being. Human amnion has been used for many years as a temporary biological wound dressing in the management of partial thickness burns. The observed advantages of human amnion treatment include pain relief, ease of use, prevention of infection and acceleration of wound healing. OBJECTIVE: This study evaluated our 7 years of working with dried irradiated human amnion in the treatment of facial burns. METHOD: A review of patients, treated with dried human amnion for facial burns between 2001 and 2008. Demographic details collected included age, gender, total facial surface area burned, type of burn and cause of injury. The effectiveness of the treatment was determined by wound infection rate, frequency of dressing reapplication, healing time and resulting scarring. RESULTS: Thirty-three patients with superficial partial thickness burn were identified (25 males, 8 females). The average age of the patients was 16.5 years (range: 8 months to 64 years). The causes included scalding (n=15), contact burning (n=13) and flash burning (n=5). The mean percent total facial surface area burned was 2.7% (range: 0.5-8.5%). None of the patients developed facial wound infections. Eighty-five percent (n=28) of the patients needed a single application of the dried amnion. The average healing time was 5.4 days (range: 2-14 days). Thirteen patients (39%) had burns confined to the facial area, of which three were discharged and treated as outpatients. Long-term follow up showed two hypopigmented scars, one hyperpigmented scar and one hypertrophic scar. CONCLUSION: Superficial partial thickness facial burns can be effectively treated with dried irradiated human amnion membrane.

The application of glycerol-preserved skin allograft in the treatment of burn injuries: an analysis based on indications.

INTRODUCTION: Glycerol-preserved skin allograft (GPA) plays a crucial role in the management of burns. Its indications include wound-bed preparation, definitive dressing and sandwich grafting technique. OBJECTIVE: We analysed the experience of using GPA and its efficacy in burn treatment in our burn centre. METHODS: All burns managed with GPA in our burn centre from October 2001 to May 2008 were analysed. RESULTS: Mean total body surface area (TBSA) of 43 consecutive cases was 28.7%. GPA adhered to the wound for an average of 8.4 days before rejection. The length of hospital stay of the survivors was 42.5 days. The autograft take after wound-bed preparation with GPA was 88.4%. For sandwich grafting technique, the autograft take was 74.4%. When GPA was applied for partial-thickness burn as definitive dressing, all patients achieved complete healing within an average of 19 days without further surgical intervention. Despite colonisation of burn wounds after application of skin allograft, the outcomes of autograft take and wound healing were not significantly different. CONCLUSION: The selective and strategic use of the GPA in major burn patients ensures optimal benefits in the management of burns. It is versatile in various categories of burn wounds with minimal morbidity.

The versatility of a glycerol-preserved skin allograft as an adjunctive treatment to free flap reconstruction.

Skin allografts have been used in medical practice for over a century owing to their unique composition as a biological dressing. Skin allografts can be obtained in several preparations such as cryopreserved, glycerol-preserved, and fresh allograft. A glycerol-preserved allograft (GPA) was introduced in the early 1980s. It has several advantages compared with other dressings such as ease of processing, storage and transport, lower cost, less antigenicity, antimicrobial properties, and neo-vascularisation promoting properties. Skin allografts are mainly used in the management of severe burn injuries, chronic ulcers, and complex, traumatic wounds. Published reports of the use of skin allografts in association with free flap surgery are few or non existent. We would like to share our experience of several cases of free tissue transfer that utilised GPA as a temporary wound dressing in multiple scenarios. On the basis of this case series, we would like to recommend that a GPA be used as a temporary dressing in conjunction with free flap surgery when required to protect the flap pedicle, allowing time for the edema to subside and the wound can then be closed for a better aesthetic outcome.

Gamma-ray spectroscopy at the limits: first observation of rotational bands in 255Lr.

The rotational band structure of 255Lr has been investigated using advanced in-beam gamma-ray spectroscopic techniques. To date, 255Lr is the heaviest nucleus to be studied in this manner. One rotational band has been unambiguously observed and strong evidence for a second rotational structure was found. The structures are tentatively assigned to be based on the 1/2-[521] and 7/2-[514] Nilsson states, consistent with assignments from recently obtained alpha decay data. The experimental rotational band dynamic moment of inertia is used to test self-consistent mean-field calculations using the Skyrme SLy4 interaction and a density-dependent pairing force.

Structure of 240Pu: evidence for octupole phonon condensation?

The expanded level structure of 240Pu available from the present study highlights the role of strong octupole correlations in this nucleus. In addition to a delayed alignment in the yrast band, the observations include the presence of both I(+)-->(I-1)(-) and I(-)-->(I-1)(+)E1 transitions linking states of the yrast and negative-parity bands at high spin and the presence of an additional even-spin, positive-parity band deexciting exclusively to the negative-parity sequence. The observations appear to be consistent with expectations based on the recently proposed concept of octupole phonon condensation.

Precise electromagnetic tests of ab initio calculations of light nuclei: states in 10Be.

In order to test ab initio calculations of light nuclei, we have remeasured lifetimes in 10Be using the Doppler shift attenuation method (DSAM) following the 7Li(7Li,alpha)10Be reaction at 8 and 10 MeV. The new experiments significantly reduce systematic uncertainties in the DSAM technique. The J(pi) = 2(1)(+) state at 3.37 MeV has tau = 205 +/- (5)(stat) +/- (7)(sys) fs corresponding to a B(E2 down) of 9.2(3)e(2) fm(4) in broad agreement with many calculations. The J(pi) = 2(2)(+) state at 5.96 MeV was found to have a B(E2 down) of 0.11(2)e(2) fm(4) and provides a more discriminating test of nuclear models. New Green's function Monte Carlo calculations for these states and transitions with a number of Hamiltonians are also reported and compared to experiment.

Collective oblate rotation at high spins in neutron-rich 180Hf.

We report on experimental evidence for collective oblate rotation becoming favored at high spins in a rigid, well-deformed, axially symmetric nucleus. Excited states established up to spin 20variant Planck's over 2pi in 180Hf are consistent with predictions that nucleon alignments would favor oblate over prolate shapes at high spins in neutron-rich Hf isotopes. The results highlight the influence of valence orbitals on the interplay between nucleon alignments and nuclear shapes and provide a rare example of independent particle dynamics in competing potential wells.

Motional narrowing and ergodic bands in excited superdeformed states of 194Hg.

The E(gamma) - E(gamma) coincidence spectra from the electromagnetic decay of excited superdeformed states in (194)Hg reveal surprisingly narrow ridges, parallel to the diagonal. A total of 100-150 excited bands are found to contribute to these ridges, which account for nearly all the unresolved E2 decay strength. Comparison with theory suggests that these excited bands have many components in their wave functions, yet they display remarkable rotational coherence. This phenomenon can be explained in terms of the combination of shell effects and motional narrowing.

Effect of a triaxial nuclear shape on proton tunneling: the decay and structure of 145Tm.

Gamma rays deexciting states in the proton emitter 145Tm were observed using the recoil-decay tagging method. The 145Tm ground-state rotational band was found to exhibit the properties expected for an h{11/2} proton decoupled band. In addition, coincidences between protons feeding the 2{+} state in 144Er and the 2{+}-->0{+} gamma-ray transition were detected, the first measurement of this kind, leading to a more precise value for the 2{+} excitation energy of 329(1) keV. Calculations with the particle-rotor model and the core quasiparticle coupling model indicate that the properties of the pi{11/2} band and the proton-decay rates in 145Tm are consistent with the presence of triaxiality with an asymmetry parameter gamma approximately 20 degrees .