Finding related sentence pairs in MEDLINE

We explore the feasibility of automatically identifying sentences in different MEDLINE abstracts that are related in meaning. We compared traditional vector space models with machine learning methods for detecting relatedness, and found that machine learning was superior. The Huber method, a variant of Support Vector Machines which minimizes the modified Huber loss function, achieves 73% precision when the score cutoff is set high enough to identify about one related sentence per abstract on average. We illustrate how an abstract viewed in PubMed might be modified to present the related sentences found in other abstracts by this automatic procedure

O peroksidnim antimalaricima

Several dicyclohexylidene tetraoxanes were prepared in order to gain a further insight into structure-activity relationship of this kind of antimalarials. The tetraoxanes 2-5, obtained as a cis/trans mixture, showed pronounced antimalarial activity against Plasmodium falciparum chloroquine susceptible D6, chloroquine resistant W2 and multidrug-resistant TM91C235 (Thailand) strains. They have better than or similar activity to the corresponding desmethyl dicyclohexylidene derivatives. Two chimeric endoperoxides with superior antimalarial activity to the natural product ascaridole were also synthesized.U ovom radu prikazana je sinteza nekoliko dicikiloheksilidenskih tetraoksana u cilju sagledavanja odnosa struktura-aktivnost ove vrste antimalarika. Jedinjenja 2-5 dobijena kao (cis,trans)-smese pokazala su izraženu antimalarijsku aktivnost prema D6, W2 i TM91C235 (Thailand) sojevima P. falciparum. Ona imaju bolju ili sličnu aktivnost od odgovarajućih desmetil cikloheksilidenskih derivata. Sintetisana su i dva endoperoksida himerne strukture znatno izraženije aktivnosti od prirodnog proizvoda askaridola.

Thick target preparation and isolation of 186Re from high current production via the 186W(d,2n)186Re reaction

Rhenium-186 has a half-life (t1/2 = 3.72 days) and emission of both gamma and beta particles that make it very attractive for use as a theranostic agent in targeted radionuclide therapy. 186Re can be readily prepared by the 185Re(n,γ)186Re reac-tion1. However, that reaction results in low specific activity, severely limiting the use of reactor produced 186Re in radiopharmaceuticals. It has previously been shown that high specific activity 186Re can be produced by cyclotron irradiations of 186W with protons and deuterons2,3. In this investigation we evaluated the 186W(d,2n)186Re reaction using thick target irradiations at higher incident deuteron energies and beam currents than previously reported. We elected not to use copper or aluminum foils in the preparation of our 186W targets due to their activation in the deuteron beam, so part of the investigation was an evaluation of an alternate method for preparing thick targets that withstand μA beam currents. Irradiation of 186W. Initial thick targets (~600-1100 mg) were prepared using 96.86% enriched 186W by hydraulic pressing (6.9 MPa) of tungsten metal powder into an aluminum target support. Those thick targets were irradiated for 10 minu-tes at 10 µA with nominal extracted deuteron energies of 15, 17, 20, 22, and 24 MeV. Isolation of 186Re. Irradiated targets were dissolved with H2O2 and basified with (NH4)2CO3 prior to separation using column(s) of ~100–300 mg Analig Tc-02 resin. Columns were washed with (NH4)2CO3 and the rhenium was eluted with ~80˚C H2O. Gamma-ray spectroscopy was per-formed to assess production yields, extraction yields, and radionuclidic byproducts. Recycling target material. When tested on a natural abundance W target, recovery of the oxidized WO4- target material from the resin was found to proceed rapidly with the addition of 4M HCl in the form of hydrated WO3. The excess water in the WO3 was then removed by calcination at 800 °C for 4 hours. This material was found to undergo reduction to metallic W at elevated temperatures (~1550 °C) in a tube furnace under an inert atmosphere (Ar). Quanti-fication of % reduction and composition analyses were accomplished with SEM, EDS, and XRD and were used to characterize and compare both the WO3 and reduced Wmetal products to a sample of commercially available material. Structural enhancement by surface annealing. In some experiments ~1 g WO3 pellets were prepared from Wmetal that had been chemically treated to simulate the target material recovery process described above. Following calcination, the WO3 was allowed to cool to ambient temperature, pulverized with a mortar and pestle and then uniaxially pressed at 13.8 MPa into 13 mm pellets. Conversion of the WO3 back to Wmetal in pellet form was accomplished in a tube furnace under flowing Ar at 1550 °C for 8 hours. Material characterization and product composition analyses were conducted with SEM, EDS, and XRD spectroscopy. Graphite-encased W targets. Irradiations were conducted at 20 μA with a nominal extracted deuteron energy of 17 MeV using thick targets (~750 mg) of natural abundance tungsten metal powder uniaxially pressed into an aluminum target support between layers of graphite pow-der (100 mg on top, 50 mg on the bottom). Targets were then dissolved as previously described and preliminary radiochemical isola-tion yields obtained by counting in a dose calibrator. Although irradiations of W targets were possible at 10 μA currents, difficulties were encountered in maintaining the structural integrity of the full-thickness pressed target pellets under higher beam currents. This led to further investigation of the target design for irradiations conducted at higher beam currents. Comprehensive target material characterization via analysis by SEM, EDS, XRD, and Raman Spectroscopy allowed for a complete redesign of the target maximizing the structural integrity of the pressed target pellet without impacting production or isolation. At the 10 A current, target mass loss following irradiation of an enriched 186W target was < 1 % and typical separation yields in excess of 70 % were observed. Saturated yields and percent of both 183Re (t½ = 70 days) and 184gRe (t½ = 35 days) relative to 186gRe (decay corrected to EOB) are reported in TABLE 1 below. The reason for the anomalously low yield at 24 MeV is unknown, but might be explained by poor beam alignment and/or rhenium volatility during irradiation. Under these irradiation conditions, recovery yields of the W target material from the recycling process were found to be in excess of 90% with no discernable differences noted when compared to commercially available Wmetal and WO3. Conceptually, increasing the structural integrity of pressed WO3 targets by high temperature heat treatment under an inert atmosphere is intriguing. However, the treated pellets lacked both density and structural stability resulting in disintegration upon manipulation , despite the initially encouraging energy dispersive X-ray spectroscopy (EDS) determination that 94.9% percent of the WO3 material in each pellet had been reduced to metallic W. The use of powdered graphite as a target stabi-lizing agent provided successful irradiation of natural abundance W under conditions where non-stabilized targets failed (20 µA at 17 MeV for 10 minutes). Target mass loss following irradiation of a natW target was < 1 % and a separation yield in excess of 97 % was obtained. In conclusion, the theranostic radionuclide 186Re was produced in thick targets via the 186W(d,2n) reaction. It was found that pressed W metal could be used for beam currents of 10 μA or less. For deuteron irradiations at higher beam currents, a method involving pressing W metal between two layers of graphite provides increased target stability. Both target configurations allow high recovery of radioactivity from the W target material, and a solid phase extraction method allows good recovery of 186Re. An effective approach to the recycling of enriched W has been developed using elevated temperature under an inert atmosphere. Further studies are underway with 186W targets sandwiched by graphite to assess 186Re production yields, levels of contaminant radiorhenium, power deposition, and enriched 186W material requirements under escalated irradiation conditions (20 µA and 17 MeV for up to 2 hours)

Notes of a Meeting Held in the Diplomatic Reception Room of the Department of State on Monday, March 20, 1911

The document is a carbon transcript of notes from a meeting held in the State Department respecting the necessity of more such meetings, the present organization of the Department, expenditures, and esprit de corps. Present at the meeting were: The Assistant Secretaries, the Solicitor, the Director of the Consular Service, the Chief Clerk and the Chiefs and Assistant Chiefs of the Divisions and Bureaus of the Department.https://digitalcommons.ursinus.edu/fmhw_speeches/1004/thumbnail.jp

Targetry investigations of 186Re production via proton induced reactions on natural Osmium disulfide and Tungsten disulfide targets

Introduction Radioisotopes play an important role in nuclear medicine and represent powerful tools for imaging and therapy. With the extensive use of 99mTc-based imaging agents, therapeutic rhenium analogues are highly desirable. Rhenium-186 emits therapeutic − particles with an endpoint-energy of 1.07 MeV, allowing for a small, targeted tissue range of 3.6 mm. Additionally, its low abundance γ-ray emission of 137.2 keV (9.42 %) allows for in vivo tracking of a radiolabeled compounds and dosimetry calculations. With a longer half-life of 3.718 days, synthesis and shipment of Re-186 based radiopharmaceuticals is not limited. Rhenium-186 can be produced either in a reactor or in an accelerator. Currently, Re-186 is produced in a reactor via the 185Re(n,γ) reaction resulting in low specific activity which makes its therapeutic application limited.[1] Production in an accelerator, such as the PETtrace at the University of Missouri Research Reactor (MURR), can theoretically provide a specific activity of 34,600 Ci.mmol−1 Re[2], which represents a 62 fold increase over reactor produced 186Re. The studies reported herein focused on the evaluation of accelerator-based reaction pathways to produce high specific activity (HSA) 186Re. Those pathways include proton and deuteron bombardment of tungsten and osmium targets by the following reactions: 186W(p,n)186Re, 186W(d,2n) 186Re, 189Os(p,α)186Re, and 192Os(p,α3n)186Re. Additional information on target design related to the determination and optimization of production rates, radionuclidic purity, and yield are presented. Material and Methods Osmium and tungsten metals are very hard and thus very brittle. Attempts at pressing the pure metal into aluminum backings resulted in chalky targets, which easily crumbled during handling. Osmium disulfide (OsS2) and tungsten disulfide (WS2) were identified to provide a softer, less brittle chemical form for targets. OsS2 and WS2 targets were prepared using a unilateral press with a 13 mm diameter die to form pressed powder discs. A simple target holder design (FIG. 1) was implemented to provide a stabilizing platform for the pressed discs. The target material was sealed in place with epoxy using a thin aluminum foil pressed over the target face. Initial irradiations of OsS2 were performed using the 16 MeV GE PETtrace cyclotron at MURR. Irradiations were performed for 30–60 minutes with proton beam currents of 10–20 µA. Following irradiation, the OsS2 targets were dissolved in NaOCl and the pH adjusted using NaOH. The resultant aqueous solution was mixed with methyl ethyl ketone (MEK), with the lipophilic perrhenate being extracted into the MEK layer and the osmium and iridium remaining in the aqueous layer. The MEK extracts were then passed through an acidic alumina column to remove any remaining osmium and iridium. Determination of rhenium and iridium activities was done by gamma spectroscopy on an HPGe detector. Preliminary irradiations on WS2 targets were performed at MURR with the beam degraded to 14 MeV with a proton beam current of 10 µA for 60 minutes. After irradiation, WS2 was dissolved using 30% H2O2 with gentle heating and counted on an HPGe detector to determine the radio-nuclides produced. Results and Conclusion Thin natOsS2 targets were produced, irradiated at 16 MeV for 10 µAh, and analyzed for radiorhenium. Under these irradiation conditions, rhenium isotopes were produced in nanocurie quantities while iridium isotopes were produced in microcurie quantities. Future studies with higher proton energies are planned to increase the production of rhenium and decrease the production of iridium. After optimizing irradiation conditions, enriched 189Os will be used for irradiations to reduce the production of unwanted radionuclides. A liquid-liquid extraction method separated the bulk of the rhenium from the iridium. The majority of the rhenium produced was recovered in the first organic aliquot with little iridium observed while the majority of the iridium and osmium was retained in the first aqueous aliquot. Target production with WS2 was successful. A thin target of natWS2 was produced and irradiated at 14 MeV for 10 µAh. Under these irradiation conditions, several rhenium isotopes were produced in microcurie quantities. Target parameters to maximize 186Re production remain to be determined before enriched 186W targets are used for irradiations to reduce the production of unwanted radionuclides. In conclusion, the potential production routes for accelerator-produced high specific activity 186Re are being evaluated. Cyclotron-based irradiations of natOsS2 targets established the feasibility of producing rhenium via the natOs(p,αxn)Re reaction. Current results indicate higher proton energies are necessary to reduce the production of unwanted iridium isotopes while increasing the production of rhenium isotopes. Preliminary irradiations were performed using the 50.5 MeV Scanditronix MC50 clinical cyclotron at the University of Washington to determine irradiation parameters for future higher energy irradiations (20–30 MeV). A rapid liquid-liquid extraction method isolated rhenium from the bulk of the iridium and osmium following irradiation. Preliminary studies indicate WS2 may also provide a suitable target material to produce 186Re via the (p,n) reaction pathway

Growth rate and age effects on Mya arenaria shell chemistry: Implications for biogeochemical studies

This paper is not subject to U.S. copyright. The definitive version was published in Journal of Experimental Marine Biology and Ecology 355 (2008): 153-163, doi:10.1016/j.jembe.2007.12.022.The chemical composition of bivalve shells can reflect that of their environment, making them useful indicators of climate, pollution, and ecosystem changes. However, biological factors can also influence chemical properties of biogenic carbonate. Understanding how these factors affect chemical incorporation is essential for studies that use elemental chemistry of carbonates as indicators of environmental parameters. This study examined the effects of bivalve shell growth rate and age on the incorporation of elements into juvenile softshell clams, Mya arenaria. Although previous studies have explored the effects of these two biological factors, reports have differed depending on species and environmental conditions. In addition, none of the previous studies have examined growth rate and age in the same species and within the same study. We reared clams in controlled laboratory conditions and used solution-based inductively coupled plasma mass spectrometry (ICP-MS) analysis to explore whether growth rate affects elemental incorporation into shell. Growth rate was negatively correlated with Mg, Mn, and Ba shell concentration, possibly due to increased discrimination ability with size. The relationship between growth rate and Pb and Sr was unresolved. To determine age effects on incorporation, we used laser ablation ICP-MS to measure changes in chemical composition across shells of individual clams. Age affected incorporation of Mn, Sr, and Ba within the juvenile shell, primarily due to significantly different elemental composition of early shell material compared to shell accreted later in life. Variability in shell composition increased closer to the umbo (hinge), which may be the result of methodology or may indicate an increased ability with age to discriminate against ions that are not calcium or carbonate. The effects of age and growth rate on elemental incorporation have the potential to bias data interpretation and should be considered in any biogeochemical study that uses bivalves as environmental indicators.This work was supported by NSF project numbers OCE-0241855 and OCE-0215905