Core-Collapse Very Massive Stars: Evolution, Explosion, and Nucleosynthesis of Population III 500 -- 1000 M⊙M_{\odot} Stars

We calculate evolution, collapse, explosion, and nucleosynthesis of Population III very-massive stars with 500$M_{\odot}$ and 1000$M_{\odot}$. Presupernova evolution is calculated in spherical symmetry. Collapse and explosion are calculated by a two-dimensional code, based on the bipolar jet models. We compare the results of nucleosynthesis with the abundance patterns of intracluster matter, hot gases in M82, and extremely metal-poor stars in the Galactic halo. It was found that both 500$M_{\odot}$ and 1000$M_{\odot}$ models enter the region of pair-instability but continue to undergo core collapse. In the presupernova stage, silicon burning regions occupy a large fraction, more than 20% of the total mass. For moderately aspherical explosions, the patterns of nucleosynthesis match the observational data of both intracluster medium and M82. Our results suggest that explosions of Population III core-collapse very-massive stars contribute significantly to the chemical evolution of gases in clusters of galaxies. For Galactic halo stars, our [O/Fe] ratios are smaller than the observational abundances. However, our proposed scenario is naturally consistent with this outcome. The final black hole masses are $\sim 230M_{\odot}$ and $\sim 500M_{\odot}$ for the $500M_{\odot}$ and 1000$M_{\odot}$ models, respectively. This result may support the view that Population III very massive stars are responsible for the origin of intermediate mass black holes which were recently reported to be discovered.Comment: 49 pages, 49 figure files, accepted to ApJ (2006, 645, 2

Determination of paroxetine in serum treated with simple pretreatment by pre-column high-performance liquid chromatography using 4-(5,6-dimethoxy-2-phthalimidinyl)-2-methoxyphenylsulfonyl chloride as a fluorescent labeling reagent.

The therapeutic drug monitoring of paroxetine could be used to optimize the pharmacological treatment of depressed patients. A simple and sensitive high-performance liquid chromatography procedure was developed for the determination of paroxetine in serum. After simple pretreatment of serum (50 μL) with acetonitrile and o-phthalaldehyde, paroxetine was derivatized with 4-(5,6-dimethoxy-2-phthalimidinyl)-2-methoxyphenylsulfonyl chloride at 70°C for 20 min in borate buffer (0.1 mol/L, pH 8.0) to produce a fluorescent product. The derivative was separated on a reversed-phase column at 40°C for stepwise elution with (A) acetic acid (10 mmol/L) and (B) acetonitrile. The flow rate was 1.0 mL/min. The fluorescence intensity was monitored at excitation and emission wavelengths of 320 and 400 nm, respectively. The within-day and day-to-day relative standard deviations were 3.0-3.4 and 2.7-8.3%, respectively. The detection limit of paroxetine was 8.3 fmol at a signal-to-noise ratio of 3. As the proposed method that only requires a small quantity of serum (50 μL) is simple, sensitive and reproducible, it would be useful for clinical and biochemical research as well as drug monitoring.The therapeutic drug monitoring of paroxetine could be used to optimize the pharmacological treatment of depressed patients. A simple and sensitive high-performance liquid chromatography procedure was developed for the determination of paroxetine in serum. After simple pretreatment of serum (50 μL) with acetonitrile and o-phthalaldehyde, paroxetine was derivatized with 4-(5,6-dimethoxy-2-phthalimidinyl)-2-methoxyphenylsulfonyl chloride at 70°C for 20 min in borate buffer (0.1 mol/L, pH 8.0) to produce a fluorescent product. The derivative was separated on a reversed-phase column at 40°C for stepwise elution with (A) acetic acid (10 mmol/L) and (B) acetonitrile. The flow rate was 1.0 mL/min. The fluorescence intensity was monitored at excitation and emission wavelengths of 320 and 400 nm, respectively. The within-day and day-to-day relative standard deviations were 3.0-3.4 and 2.7-8.3%, respectively. The detection limit of paroxetine was 8.3 fmol at a signal-to-noise ratio of 3. As the proposed method that only requires a small quantity of serum (50 μL) is simple, sensitive and reproducible, it would be useful for clinical and biochemical research as well as drug monitoring

Evolution of Very Massive Population III Stars with Mass Accretion from Pre-Main Sequence to Collapse

We calculate the evolution of zero-metallicity Population III (Pop III) stars whose mass grows from the initial mass of $\sim 1M_{\odot}$ by accreting the surrounding gases. Our calculations cover a whole evolutionary stages from the pre-main sequence, via various nuclear burning stages, through the final core collapse or pair-creation instability phases. We adopt the following stellar mass-dependent accretion rates which are derived from cosmological simulations of early structure formation based on the low mass dark matter halos at redshifts $z \sim 20$: (1) the accretion rates for the first generation (Pop III.1) stars and (2) the rates for zero-metallicity but the second generation (Pop III.2) stars which are affected by radiation from the Pop III.1 stars. For comparison, we also study the evolution with the mass-dependent accretion rates which are affected by radiatibe feedback. We show that the final mass of Pop III.1 stars can be as large as $\sim 1000M_{\odot}$, beyond the mass range ($140 - 300M_{\odot}$) for the pair-instability supernovae. Such massive stars undergo core-collapse to form intermediate-mass black holes, which may be the seeds for merger trees to supermassive black holes. On the other hand, Pop III.2 stars become less massive (\lsim 40 - 60M_{\odot}), being in the mass range of ordinary iron core-collapse stars. Such stars explode and eject heavy elements to contribute to chemical enrichment of the early universe as observed in the abundance patterns of extremely metal-poor stars in the Galactic halo.Comment: 24 pages, 11 figures (15 figure files

Increasing Electrode Work Function Using a Natural Molecule

Abstract Providing sustainability to organic electronics is highly demanded to reduce the negative impact of organic devices on environments and human health upon their disposal. To attain biodegradability and biocompatibility of the electronic devices, utilization of the natural molecules for the device constituents is essential. In this study, it is reported that the adsorption of caffeic acid (CfA), a polar phenylpropanoid that plants bio‐synthesize, universally increases work functions (WFs) of practical electrodes and organic films. Either vacuum‐depositing or spin‐casting CfA films on the electrode materials form a dipole layer with the negative charges on the carboxyl group exposed to the outermost surface. The preferential adsorption of the catechol moiety of CfA onto substrate surfaces drives the molecular orientation, leading to the WF increase up to 0.7 eV. As a consequence, the single‐layer devices with the CfA interlayer facilitate the hole injection in forward bias by a factor of 101–102, which validates the usability of the natural molecule for organic electronics

Necrotizing fasciitis of the thigh due to penetrated descending colon cancer: a case report

Abstract Background Necrotizing fasciitis (NF) caused by colorectal cancer is rare, and very few cases associated with colon cancer have been reported. We describe the case of a patient with NF in the left thigh due to penetration of descending colon cancer who was treated with one-stage surgical resection without creating a stoma. Case presentation An 80-year-old woman was brought to our hospital complaining of fever and difficulty with body movement. A physical examination showed subcutaneous emphysema from the left lower abdomen to the left femoral region. CT showed abscess formation with emphysema around the descending colon, and the wall of the descending colon was thickened, which led to suspicion of colon cancer. The patient was subsequently diagnosed with NF due to penetration of descending colon cancer. Left hemicolectomy and open drainage of the left femoral region was performed. The histopathological findings were well-differentiated adenocarcinoma, with the tumor grown through the serosa (T4a) and with no metastasis to lymph nodes (N0). After surgery, the patient received intensive care for septic shock and lavage of the open drainage site, and sepsis was controlled progressively. After closure of the drainage site, the patient was transferred to a different hospital at 26 days after surgery, and she has had 6-month relapse-free survival. Conclusions In NF caused by colon cancer, early one-stage resection may improve the oncological outcome. Physical status should be assessed carefully, and one-stage resection should be considered if the patient has the capacity to undergo this procedure