Z = 50 shell gap near 100Sn from intermediate-energy Coulomb excitations in even-mass 106-112Sn isotopes.

Rare isotope beams of neutron-deficient 106,108,110Sn from the fragmentation of 124Xe were employed in an intermediate-energy Coulomb excitation experiment. The measured B(E2,0(1)(+)-->2(1)(+)) values for 108Sn and 110Sn and the results obtained for the 106Sn show that the transition strengths for these nuclei are larger than predicted by current state-of-the-art shell-model calculations. This discrepancy might be explained by contributions of the protons from within the Z = 50 shell to the structure of low-energy excited states in this region.

Measurement of excited states in (40)Si and evidence for weakening of the N=28 shell gap.

Excited states in (40)Si have been established by detecting gamma rays coincident with inelastic scattering and nucleon removal reactions on a liquid hydrogen target. The low excitation energy, 986(5) keV, of the 2(1)(+) state provides evidence of a weakening in the N=28 shell closure in a neutron-rich nucleus devoid of deformation-driving proton collectivity.

Probing shell structure and shape changes in neutron-rich sulfur isotopes through transient-field g-factor measurements on fast radioactive beams of 38S and 40S.

The shell structure underlying shape changes in neutron-rich nuclei near N = 28 has been investigated by a novel application of the transient-field technique to measure the first-excited-state g factors in 38S and 40S produced as fast radioactive beams. There is a fine balance between proton and neutron contributions to the magnetic moments in both nuclei. The g factor of deformed 40S does not resemble that of a conventional collective nucleus because spin contributions are more important than usual.

Quadrupole deformation of the self-conjugate nucleus 72Kr.

We report on the first determination of the absolute B(E2;0+(1)-->2+(1)) excitation strength in the N=Z nucleus 72Kr. 72Kr is the heaviest N=Z nucleus for which this quantity has been measured and provides a benchmark in a region of the nuclear chart dominated by rapidly changing deformations and shapes mediated by the interplay of strongly oblate and prolate-driving orbitals. The deduced quadrupole deformation strength is in agreement with a variety of self-consistent models that predict an oblate shape for the ground state of 72Kr. Large-scale shell-model Monte Carlo calculations reproduce the experimental B(E2) value and link the result to the occupation of the deformation-driving g9/2 orbit.

'Magic' nucleus 42Si.

Nuclear shell structures--the distribution of the quantum states of individual protons and neutrons--provide one of our most important guides for understanding the stability of atomic nuclei. Nuclei with 'magic numbers' of protons and/or neutrons (corresponding to closed shells of strongly bound nucleons) are particularly stable. Whether the major shell closures and magic numbers change in very neutron-rich nuclei (potentially causing shape deformations) is a fundamental, and at present open, question. A unique opportunity to study these shell effects is offered by the 42Si nucleus, which has 28 neutrons--a magic number in stable nuclei--and 14 protons. This nucleus has a 12-neutron excess over the heaviest stable silicon nuclide, and has only one neutron fewer than the heaviest silicon nuclide observed so far. Here we report measurements of 42Si and two neighbouring nuclei using a technique involving one- and two-nucleon knockout from beams of exotic nuclei. We present strong evidence for a well-developed proton subshell closure at Z = 14 (14 protons), the near degeneracy of two different (s(1/2) and d(3/2)) proton orbits in the vicinity of 42Si, and a nearly spherical shape for 42Si.

Half-life of the doubly magic r-process nucleus 78Ni.

Nuclei with magic numbers serve as important benchmarks in nuclear theory. In addition, neutron-rich nuclei play an important role in the astrophysical rapid neutron-capture process (r process). 78Ni is the only doubly magic nucleus that is also an important waiting point in the r process, and serves as a major bottleneck in the synthesis of heavier elements. The half-life of 78Ni has been experimentally deduced for the first time at the Coupled Cyclotron Facility of the National Superconducting Cyclotron Laboratory at Michigan State University, and was found to be 110(+100)(-60) ms. In the same experiment, a first half-life was deduced for 77Ni of 128(+27)(-33) ms, and more precise half-lives were deduced for 75Ni and 76Ni of 344(+20)(-24) ms and 238(+15)(-18) ms, respectively.

29Na: defining the edge of the island of inversion for Z=11.

The low-energy level structure of the exotic Na isotopes (28,29)Na has been investigated through beta-delayed gamma spectroscopy. The N=20 isotones for Z=10-12 are considered to belong to the "island of inversion" where intruder configurations dominate the ground state wave function. However, it is an open question as to where and how the transition from normal to intruder dominated configurations happens in an isotopic chain. The present work, which presents the first detailed spectroscopy of (28,29)Na, clearly demonstrates that such a transition in the Na isotopes occurs between 28Na (N=17) and 29Na (N=18), supporting the smaller N=20 shell gap in neutron-rich sd shell nuclei. The evidence for inverted shell structure is found in beta-decay branching ratios, intruder dominated spectroscopy of low-lying states, and shell model analysis.

Reduced occupancy of the deeply bound 0d(5/2) neutron state in 32Ar.

The 9Be(32Ar, 31Ar)X reaction, leading to the 5/2+ ground state of a nucleus at the proton drip line, has a cross section of 10.4(13) mb at a beam energy of 65.1 MeV/nucleon. This translates into a spectroscopic factor that is only 24(3)% of that predicted by the many-body shell-model theory. We introduce refinements to the eikonal reaction theory used to extract the spectroscopic factor to clarify that this very strong reduction represents an effect of nuclear structure. We suggest that it reflects correlation effects linked to the high neutron separation energy (22.0 MeV) for this state.

New approach for measuring properties of rp-process nuclei.

A new experimental approach was developed that can reduce the uncertainties in astrophysical rapid proton capture (rp) process calculations due to nuclear data. This approach utilizes neutron removal from a radioactive ion beam to populate the nuclear states of interest. Excited states were deduced by the gamma-decay spectra measured in a semiconductor Ge-detector array. In the first case studied, 33Ar, excited states were measured with uncertainties of several keV. The 2 orders of magnitude improvement in the uncertainty of the level energies resulted in a 3 orders of magnitude improvement in the uncertainty of the calculated 32Cl(p,gamma)33Ar rate that is critical to the modeling of the rp process. This approach has the potential to measure key properties of almost all interesting nuclei on the rp-process path.

Unambiguous identification of three beta-decaying isomers in 70Cu.

Using resonant laser ionization, beta-decay studies, and for the first time mass measurements, three beta-decaying states have been unambiguously identified in 70Cu. A mass excess of -62 976.1(1.6) keV and a half-life of 44.5(2) s for the (6-) ground state have been determined. The level energies of the (3-) isomer at 101.1(3) keV with T(1/2)=33(2) s and the 1+ isomer at 242.4(3) keV with T(1/2)=6.6(2) s are confirmed by high-precision mass measurements. The low-lying levels of 70Cu populated in the decay of 70Ni and in transfer reactions compare well with large-scale shell-model calculations, and the wave functions appear to be dominated by one proton-one neutron configurations outside the closed Z=28 shell and N=40 subshell. This does not apply to the 1+ state at 1980 keV which exhibits a particular feeding and deexcitation pattern not reproduced by the shell-model calculations.

Lowest excitations in 56Ti and the predicted N=34 shell closure.

Recent experimental characterization of the subshell closure at N=32 in the Ca, Ti, and Cr isotones has stimulated shell-model calculations that indicated the possibility that the N=34 isotones of these same elements could exhibit characteristics of a shell closure, namely, a high energy for the first excited 2(+) level. To that end, we have studied the decay of 56Sc produced in fragmentation reactions and identified new gamma rays in the daughter N=34 isotone 56Ti. The first 2(+) level is found at an energy of 1127 keV, well below the expected position that would indicate the presence of an N=34 shell closure in 56Ti.

New direct reaction: two-proton knockout from neutron-rich nuclei.

The reaction 9Be(28Mg,26Ne+gamma)X has been studied at 82 MeV/nucleon together with two similar cases, 30Mg and 34Si. Strong evidence that the reactions are direct is offered by the parallel-momentum distributions of the reaction residues and by the inclusive cross sections. The pattern of the partial cross sections for 28Mg suggests the presence of correlations. A preliminary theoretical discussion based on eikonal reaction theory and the many-body shell model is presented. The reaction holds great promise for the study of neutron-rich nuclei.

Chemical components of shredded paper insulation: a preliminary study.

We conducted an evaluation of shredded paper insulation to identify potentially toxic components. The study was to provide a preliminary characterization of a few samples of insulation currently in use. The following samples were analyzed: previously produced insulation (PPI) containing fire retardants, shredded recycled paper (PPI feedstock), freshly produced insulation (FPI), and insulation which had been installed in a residence (II). Volatile constituents were analyzed by GC-MS from headspace air of samples held at room temperature or heated to 90 degrees C. Extractable constituents were sampled by extracting with methylene chloride, and analyzing by GC-MS. Formaldehyde analysis was done according to EPA Method TO11. Headspace air at room temperature contained no detectable quantities of volatile constituents for any sample measured. In headspace air at 90 degrees C, only PPI contained traces of aliphatic and aromatic hydrocarbons and higher aldehydes, and FPI traces of toluene. Extracts of PPI contained traces of octadecadienoic acid methyl ester and aliphatic and aromatic hydrocarbons and higher aldehydes. Extracts of PPI feedstock contained traces of a substituted cyclohexenecarboxylic acid. FPI contained extractable diethyl phthalate (30-50 micrograms/g). Extracts of II contained traces of methyl palmitate, an octadecenoic acid methyl ester, and a phthalate plasticizer. No formaldehyde was detected. PPI was composed of approximately 98 percent paper fiber and 2 percent pre-gelatinized starch. PPI samples agglomerated together with less than 0.01 percent separating from clumps as fine dust. Boron and sodium were expected and confirmed because they were added to PPI and FPI as fire retardants. Chromium, copper, iron, potassium, magnesium, manganese, phosphorus, and silicon were present at detectable concentrations. Study calculations indicate that an occupant would have to completely consume all the fine particles produced from 3.3 kg of insulation per day to have an intake of boron equivalent to the EPA RfD. No other constituent appeared to be present even close to toxicologically relevant amounts.

Fulminant disseminated toxoplasmosis in an HIV patient.

Disseminated toxoplasmosis in AIDS is a rare condition. We present an unusual case of a fulminant form of disseminated toxoplasmosis in a young male homosexual. He was a 30-year-old HIV-positive (diagnosed 4 months earlier), admitted with a 5-day history of diarrhea, vomiting, fever, and cough. He had been generally healthy except for an 8-week history of weight loss and malaise. On admission, except for a temperature of 37.6 degrees C, the physical examination was normal. He was treated symptomatically. Four days after admission he suddenly became short of breath. Despite intensive management, he continued to deteriorate and expired 6 h later. Postmortem examination revealed disseminated toxoplasmosis involving the heart, lungs, brain, stomach, small intestine, and colon. This is an unusual presentation of disseminated toxoplasmosis because of its rapid course with no prior indication of infection. To our knowledge, such an atypical and rapid downhill course of toxoplasmosis (with minimal clinical and laboratory features) has not been reported previously. Increased awareness of this infection in all HIV patients and its possibly rapid course is needed.

Comparison of serum CA 19-9 and CEA levels in a population at high risk for colorectal cancer.

The sera of 563 patients who underwent colonoscopy were assayed for glycolipid antigen CA 19-9 and CEA. These patients represented a broad spectrum of clinical diseases ranging from advanced metastatic cancer of the colon, pancreas, or stomach to those with negative colonoscopic examination. Sensitivity and specificity for CA 19-9 and CEA were calculated using the following clinical definitions. Malignant or pre-malignant disease was defined as colon, pancreatic or stomach carcinoma, stomach dysplasia, atypical adenomatous polyp, atypical villous adenoma, carcinoma in situ and carcinoma in an adenomatous polyp. When the normal group included patients with adenomatous polyp, hyperplastic adenoma, inflammatory disease and patients with no disease apparent, the sensitivity and specificity for CA 19-9 was 23% and 96%, and for CEA, 23% and 95%, respectively. When adenomatous polyp patients were placed in the malignant or pre-malignant disease group, the sensitivity and specificity for CA 19-9 was 8% and 96%, and for CEA, 11% and 95%, respectively. When comparing CA 19-9 and CEA in colorectal carcinoma, the percent positivity of the CEA assay was equal to, or better than, CA 19-9 in all Dukes' stages. In pancreatic carcinomas CA 19-9 showed better diagnostic performance than CEA.

Distribution of cyclosporine in blood of a renal-transplant recipient with type V hyperlipoproteinemia.

A patient with severe type V hyperlipoproteinemia and chronic end-stage renal disease received a renal transplant and therapy with cyclosporine. Concentrations of the drug in plasma as determined by liquid chromatography appeared extraordinarily high for the dose ingested. When we measured the drug in the plasma, plasma cleared by ultracentrifugation, leukocytes, erythrocytes, and whole blood, we found that the high concentrations of cyclosporine were associated with the chylomicrons that always were present in this patient's blood. Cyclosporine added directly to this patient's plasma was less associated with the plasma lipids. Isolated lymphocytes and kidney slices incubated with plasma from this patient bound no more drug than when incubated with nonhyperlipemic plasma containing cyclosporine at a normal therapeutic concentration. We conclude that the cyclosporine associated with the chylomicrons in this patient was not biologically available to either lymphocytes or kidney tissue. We strongly recommend the use of chylomicron-cleared plasma for therapeutic drug monitoring of cyclosporine in type V hyperlipoproteinemic patients.

Asymmetric septal hypertrophy of the heart. New findings concerning the possible etiology of sudden deaths in five males.

This report describes certain interesting postmortem findings in the hearts of five subjects who died suddenly, silently, and unexpectedly, and in whom the only significant abnormality at autopsy was asymmetric septal hypertrophy (ASH) of the heart. Deep clefts, cystic faults, and dilated vascular channels were not only seen within the septal myocardium in all the hearts, but also within the left ventricular free walls of two hearts. The septal myocardium and the left ventricular free walls of two hearts and the A-V node and His bundle of one heart demonstrated mural and luminal thrombi of several dilated vascular channels. In another heart, foci of cardiocytic myofibrillar degeneration were seen, especially close to narrowed small coronary vessels. Fetal dispersion and fibrosis of the A-V node and His bundle were evident in one heart. These abnormalities in the conducting system and the ventricular myocardium suggest that the hearts of subjects with ASH are not only excellent anatomic substrates for lethal arrhythmias, but also are bound to be hemodynamically impaired. We believe that conditions such as hypoxia, increased oxygen demand by the heart or abnormal sympathetic stimulus may easily trigger fatal arrhythmias in such individuals, thereby causing sudden death.

The role of the chimpanzee in the evaluation of the risk of foreign chemicals to man.

Various species of laboratory animals are used to evaluate the efficacy and safety of drugs in man. However, the extrapolation of data from animals to man is often complicated by species differences in the disposition of foreign chemicals. The findings of comparative metabolism studies are used to illustrate species differences in metabolic pathways, rates of biotransformation, kinetics, and excretion routes. Biochemical and structural consequences of the significant differences in enzyme induction between rodents and primate species are discussed. Among the primates, the chimpanzee has been shown to be the most closely related to man not only in the disposition of xenobiotics, but also in the aspects of endocrinology, serology, and immunology. It would, therefore, be the best possible model to predict the fate and effects of foreign chemicals in man. Due to the limited availability of chimpanzees, however, they can only be used for the evaluation of the most critical chemicals and drugs. Comparative metabolism and disposition studies, e.g., of compounds representative of classes of chemicals in chimpanzees and other animals. Only when the pertinent differences between the selected test species and man are known can correct extrapolations to man be made.

A fatal maprotiline intoxication.

A fatal maprotiline intoxication is presented. The postmortem anatomical and toxicologic findings are discussed, as is the mechanism of maprotiline toxicity. This report is, to the best of our knowledge, the sixth fatal maprotiline poisoning in the medical literature.

Testicular gonadal stromal (Sertoli cell) tumor.

Eighty-one cases of testicular gonadal stromal tumor have been reported in the literature. An additional case is herein reported. The pathologic, immunohistologic, and histogenetic aspects are presented.