Constraining Neutron Capture Cross Sections for Unstable Nuclei with Surrogate Reaction Data and Theory

Obtaining reliable data for nuclear reactions on unstable isotopes remains an extremely important task and a formidable challenge. Neutron capture cross sections-crucial ingredients for models of astrophysical processes, national security applications, and simulations of nuclear energy generation-are particularly elusive, as both projectile and target in the reaction are unstable. We demonstrate a new method for determining cross sections for neutron capture on unstable isotopes, using ^{87}Y(n,γ) as a prototype. To validate the method, a benchmark experiment is carried out to obtain the known ^{90}Zr(n,γ) cross section analogously. Our approach, which employs an indirect ("surrogate") measurement combined with theory, can be generalized to a larger class of nuclear reactions. It can be used both with traditional stable-beam experiments and in inverse kinematics at rare-isotope facilities.

β decay of (38)Ca: sensitive test of isospin symmetry-breaking corrections from mirror superallowed 0+ → 0+ transitions

We report the first branching-ratio measurement of the superallowed 0+→0+β transition from Ca38. The result, 0.7728(16), leads to an ft value of 3062.3(68) s with a relative precision of ±0.2%. This makes possible a high-precision comparison of the ft values for the mirror superallowed transitions, Ca38→38mK and K38m→Ar38, which sensitively tests the isospin symmetry-breaking corrections required to extract Vud, the up-down quark-mixing element of the Cabibbo-Kobayashi-Maskawa (CKM) matrix, from superallowed β decay. The result supports the corrections currently used and points the way to even tighter constraints on CKM unitarity.

Experimental validation of the largest calculated isospin-symmetry-breaking effect in a superallowed Fermi decay

A precision measurement of the γ yields following the β decay of (32)Cl has determined its isobaric-analogue branch to be (22.47(-0.18)(+0.21))%. Since it is an almost pure-Fermi decay, we can also determine the amount of isospin-symmetry breaking in this superallowed transition. We find a very large value, δ(C) = 5.3(9)%, in agreement with a shell-model calculation. This result sets a benchmark for isospin-symmetry-breaking calculations and lends support for similarly calculated, yet smaller, corrections that are currently applied to 0+ → 0 + transitions for tests of the standard model.

Long-term settlement behaviour of MSW landfills with various fill ages

MSW landfill settlement characteristics are peculiar because a considerable amount of settlement occurs due to the decomposition of waste organic solids for very long duration. The total amount of settlement that occurs due to this decomposition in a MSW landfill is mainly dependent upon the amount of biodegradable solid waste and hence the fill age of the MSW landfill. The settlement stabilisation period is also dependent upon the decomposition condition. In order to investigate the settlement characteristics of MSW landfills, a mathematical model was proposed and applied to settlement data of MSW landfills which have various fill ages. A data bank of model parameters were obtained and the trends were analysed. The long-term settlement behaviour of MSW landfills can be fairly well estimated by the proposed model. It is supposed that the total remaining amount of settlement might be predicted on the basis of the fill age with two appropriate design parameters.

Prevalence of porcine proliferative enteropathy and its control with tylosin in Korea

Porcine proliferative enteropathy(PPE) is an enteric disease been caused by Lawsonia intracellularis. It has become one of the critical problems in the pig industry. To investigate the prevalence of PPE in Korea, serum samples of 828 pigs from 65 herds were tested using indirect immunofluorescence antibody technique(IFA). The infection rate in individual pigs varied from 44 to 69%, whereas 100% in pig farms. The infection frequency was 57, 44.9, and 59.4% according to age respectively. Administration of tylosin in feed at a concentration of 110 ppm for 14 days reduced the infection rate of the farms. These data indicated that the high prevalence of PPE may be controlled by tylosin.

An angiographic lesion mimicking pseudo-aneurysm in cerebral arteriovenous malformation

In cerebral arteriovenous malformations (AVMs), a pseudo-aneurysm represents rupture site, and its presence is known as a factor for rebleeding. We report a case of cerebral AVM presenting with intracerebral haemorrhage in which cerebral angiography showed a lesion mimicking pseudo-aneurysm. Although the patient needed urgent surgical decompression, it was delayed because early haematoma evacuation would induce rebleeding from the rupture site. The authors attempted to occlude the pseudoaneurysm interventionally before surgery. After surgical excision, the lesion that was believed to be a pseudo-aneurysm was revealed as a partially thrombosed venous sac having a thick fibrous wall. In this report, the authors discuss the pitfalls in the interpretation of pseudo-aneurysms in angiographic AVM architecture.

Szygium aromaticum (L.) Merr. Et Perry (Myrtaceae) flower bud induces apoptosis of p815 mastocytoma cell line

This study was conducted to investigate SAFB-induced apoptosis of mast cells as it pertains to both its basic drug mechanism and the potential therapeutics of the pathologic conditions accompanying mast cell proliferation. SAFB induced many apoptotic manifestations as evidenced by changes in cell morphology, generation of DNA fragmentation, activation of caspase 3, and DNA hypoploidy. The reduction of mitochondrial membrane potential and the release of cytochrome c to cytosol were also demonstrated. However, reduction of mitochondrial membrane potential and cytochrome c release were not prevented by caspase inhibitor zVAD-fmk or PTP blockers such as bongkrekic acid and cyclosporin A. Expression levels of Bcl-2 and Fas remained unchanged following SAFB treatment. This results suggest that the clinical effect of SAFB may depend on the pharmacological mechanism regulating the demise of mast cells.

Multiple meningiomas of different pathological features: case report

Meningioma is a common intracranial tumour and it may occur not infrequently as one of the multiple tumours, especially in patients with neurofibromatosis. The incidence of multiple meningiomas (MMs) without the stigmata of neurofibromatosis is rare, ranging from 1 to 9% of all meningiomas in the literature. Multiple meningiomas with different pathologic features are even rarer, and most of them are benign histologies. The authors report an extremely rare case of MMs which were presented with malignant and benign histological features simultaneously. The underlying mechanism of MM formation is still unclear, however, subarachnoid spread was thought to be the most likely mechanism. The findings of most of MMs showed identical histopathological features and several molecular biologic studies provided evidence for the monoclonal origin of MMs to back up the above hypothesis. However, different histological features among the reported multiple meningioma cases including our particular one, suggests their origin from multicentric neoplastic foci activated by a supposed tumour-producing factor. However, we cannot completely exclude the possibility of independent progression from monoclonal origin.

Metal ion binding and activation of Streptomyces griseus dinuclear aminopeptidase: cadmium(II) binding as a model

A detailed metal binding and activation of the dinuclear aminopeptidase from Streptomyces griseus (sAP) has been analyzed and modeled by means of metal titration as well as kinetic and thermodynamic techniques using Cd2+ as a probe. Cd2+ binds to the two metal-binding sites in a sequential manner to produce a very active Cd2+-substituted derivative, particularly in the presence of Ca2+ (53% and 90%, respectively, relative to the activities of the native form in terms of kcat/Km under the same conditions). The first stepwise formation constant for the binding of metal to the dinuclear site (to form M-sAP) was found to determine the metal-binding selectivity, regardless of the magnitude of the second stepwise formation constant (to form M,M-sAP from M-sAP). Interestingly, despite the seemingly very different binding profiles for different metal ions under different conditions, all of them can be well described and fitted by the sequential binding model. In addition, Ca2+ was found to significantly affect metal binding, inhibition, and entropy of activation of this enzyme, and its role in sAP action is re-evaluated.

Identification and characterization of human endometase (Matrix metalloproteinase-26) from endometrial tumor

We report the discovery, cloning, and characterization of a novel human matrix metalloproteinase 26 (MMP-26) (matrixin) gene, endometase, an endometrial tumor-derived metalloproteinase. Among more than three million expressed sequence tags sequenced, the endometase gene was only obtained from human endometrial tumor cDNA library. Endometase mRNA was expressed specifically in human uterus, not in other tissues/cells tested, e.g. testis, heart, brain, lungs, liver, thymus, and melanoma G361. Endometase protein has a signal peptide, a propeptide domain, and a catalytic domain with a unique "cysteine switch" propeptide sequence, PHCGVPDGSD, and a zinc-binding motif, VATHEIGHSLGLQH. Endometase is 43, 41, 41, and 39% identical to human metalloelastase, stromelysin, collagenase-3, and matrilysin, respectively. The zymogen was expressed and isolated from Escherichia coli as inclusion bodies with a molecular mass of 28 kDa. The identity and homogeneity of the recombinant protein was confirmed by protein N-terminal sequencing, silver stain, and immunoblot analyses. The pro-enzyme was partially activated during the folding process. Endometase selectively cleaved type I gelatin and alpha(1)-proteinase inhibitor; however, it did not digest collagens, laminin, elastin, beta-casein, plasminogen, soybean trypsin inhibitor, or Bowman-Birk inhibitor. It hydrolyzed peptide substrates of matrixins and tumor necrosis factor-alpha converting enzyme. Endometase may selectively cleave extracellular matrix proteins, inactivate serpins, and process cytokines.

A 10(10) Rate Enhancement of Phosphodiester Hydrolysis by a Dinuclear Aminopeptidase-Transition-State Analogues as Substrates?

Streptomyces dizinc aminopeptidase (sAP) shows a specific activity of 33.7 nmol min(-1) mg(-1) toward the hydrolysis of the transition-state analogue bis-p-nitrophenylphosphate with a rate constant of k(cat)/K(m)=100 M(-1) s(-1) and a first-order rate enhancement of about 10(10), which is much superior to several Zn chemical models and comparable to some phosphodiesterases. This study suggests that sAP can serve as a novel dinuclear model system to provide further insight into dinuclear hydrolysis.