Thorium,uranium and plutonium isotopes in the Arkansas River

Radiochemical measurements of the concentrations of thorium, uranium and plutonium isotopes were carried out for the samples of Arkansas River collected at six locations in the states of Colorado and Oklahoma. The uranium to thorium ratios in the river samples were found to be highly variable and generally much greater than the ratios found in soils and in rainwater. An attempt has been made to determine the apparent²³⁰Th ages (or the times which elapsed since the last major disruption of the radioactive equilibria) from the observed²³⁰Th/²³²Th and²³⁴U/²³²Th ratios in the water samples.     

Fallout of uranium isotopes from the 1980 eruption of Mount St. Helens

A marked increase in the concentration of²³⁸U in rain was observed at Fayetteville (36 °N, 94 °W), Arkansas, after the 18 May 1980 eruption of Mount St. Helens. The fallout of natural uranium observed during the summer months of 1980 can be attributed to the 18 May 1980 events, which ejected an amount of ash material on the order of 4 km³ or about 8·10¹⁵ grams into the atmosphere.²³⁴U and²³⁵U were found to be highly enriched relative to²³⁸U in several rain samples collected at Fayetteville, Arkansas, prior to the volcanic eruption. The anomalous uranium seems to have originated from the Soviet satellite Cosmos-954, which fell over Canada, on 24 January 1978. The effect of the 25th Chinese nuclear test, which occurred on 16 October 1980, on the concentrations of uranium isotopes in rain appears to have been insignificant.     

Environmental radioactivity in Uyo //5° N, 7° 50 E/, nigeria/

A survey of the environmental radioactivity in Uyo /5° N, 7° 50 E/, Nigeria has been done for the period 1981 to 1986. An overall average of 8.5±0.5 pCi is the environmental radioactivity for the surrounding air and 8.2±0.4 pCi for the top soil. Airborne -particles were also measured using CR-39 plastic detectors. The University Campus in Uyo had an overall average -activity of 75.3±0.8 fmCi while other sectors of the town had an average of 95.2±1.1 fmCi. Our results show a non-uniform distribution of - and other radioactivity in Uyo.     

Mechanical Properties and In Vitro Physico‐chemical Reactivity of Gel‐derived SiO2–Na2O–CaO–P2O5 Glass from Sand

In the present report, a bioactive glass was synthesized from silica sand as economic substitute to alkoxy silane reagents. Sodium metasilicate (Na₂SiO₃) obtained from the sand was hydrolyzed and gelled using appropriate reagents before sintering at 950 °C for 3 h to produce glass in the system SiO₂? Na₂O? CaO? P₂O₅. Compression test was conducted to investigate the mechanical strength of the glass, while immersion studies in simulated body fluid (SBF) was used to evaluate reactivity, bioactivity and degradability. Furthermore, the glass samples were characterized by scanning electron microscopy (SEM), X‐ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and energy dispersive X‐ray spectroscopy (EDX) to evaluate the microstructure and confirm apatite formation on the glass surface. The glass, dominated by bioactive sodium calcium silicate, Na₂Ca₂Si₃O₉ (combeite) crystals, had mechanical strength of 0.37 MPa and showed potentials for application as scaffold in bone repair.     

Phytochemical analysis and antioxidant activity of the seed of Telfairia occidentalis Hook (Cucurbitaceae)

The 2,2-diphenyl-1-picryl hydrazyl (DPPH) radical, nitric oxide, reducing power, hydrogen peroxide scavenging, and total antioxidant activities of the methanol extract, n-hexane, dichloromethane, ethyl acetate, butanol and aqueous fractions of the seed of Telfairia occidentalis were evaluated. Total phenolic content was determined using the Folin–Ciocalteu method. The dichloromethane fraction exhibited the highest DPPH radical scavenging, reducing power and total antioxidant activities. Two pure compounds which were identified by FTIR, H-and 2D NMR and Mass spectroscopy as 9-octadecenoic acid (TOS B) and 10-hydroxyoctadecanoic acid (TOS C) and four oily isolates, TOS A, TOS D, TOS E and TOS F were obtained from the dichloromethane fraction. TOS E had the highest DPPH radical scavening activity comparable to that of ascorbic acid. GC-MS analysis revealed the major compounds in TOS E as 4-(2,2-Dimethyl-6-methylene cyclohexylidene)-2-butanol; 3-(3-hydroxybutyl)-2,4,4-trimethyl-2-cyclohexene-1-one and 1,2-Benzenedicarboxylic acid disooctyl ester. Thus, the seed of T. occidentalis can be consumed for its antioxidant property.     

Alpha-recoil atoms of plutonium in the environment

The -recoil effect of²³⁹Pu has been observed in environmental samples and theN ₅ ^P /N₅ ratio in these samples has been calculated. This ratio in atmospheric samples is in the range between 10^–5 and 10^–4 (atom/atom). For other contemporary terrestrial samples it is in the range between 10^–7 and 10^–6 (atom/atom), while that of uranium mineral is about 10^–10 (atom/atom). The results further explain the radioactive fallout contamination of our environment by uranium and plutonium isotopes.     

Uranium isotope anomaly in minerals

A series of leaching experiments with HF, HCl, HNO₃ were carried out on samples of uranium minerals (uraninite and carnotite samples). Anomalously high²³⁴U/²³⁸U ratios were observed in some uranium fractions. The observed²³⁴U/²³⁸U activity ratios varied between the values of 1.019±0.155 and 6.210±0.504 (Ci/Ci), while the bulk carnotite sample had an activity ratio of 1.010±0.005 (Ci/Ci). These results are interpreted as due to alpha-recoil effect and changes in oxidation state of uranium.     

Standardization of a multi-wavelength UV detector for liquid chromatography-based toxicological analysis.

The performance of a multi-wavelength UV detector for automated drug identification following liquid chromatographic separation was evaluated. The ability of selected wavelength ratios to distinguish two closely related drugs was considered at different concentrations. Calibration of the detector based on wavelength ratios was then utilized to standardize two different detectors and to evaluate instrument-to-instrument variation of a series of detectors. Reproducibility of the second-derivative zero intercept for these drug spectra was also evaluated. Standardization of detector performance by reference to these two parameters permitted the transfer of UV spectral libraries stored on one instrument to another without compromising the reliability of qualitative data.     

Essential oil constituents and biological activities of Peristrophe bicalyculata and Borreria verticillata

Peristrophe bicalyculata (Retz) Nees (Acanthaceae) or 'The Goddess of Mercy' and Borreria verticillata (L.) G.F.W. Mey., (Rubiaceae), or 'Irawo-Ile' (Yoruba, South-west, Nigeria), are annual herbs, which are poorly exploited. The volatile oils obtained by hydrodistillation in an all glass Clevenger-type apparatus from the plant samples have been investigated by gas chromatography-mass spectrometry (GC-MS). With respect to the oil of P. bicalyculata, beta-caryophyllene (33.9%), alpha-zingiberene (10.4%), germacrene D and globulol (5.0%) were the compounds occurring in abundance. The oil of B. verticillata had an abundance of phytol (56.3%) and 1, 8-cineole (20.4%), with sizeable proportions of alpha-pinene (7.1%) and p-cymene (4.0%). In addition, the volatile oils displayed promising in-vitro antimicrobial activity against the tested micro-organisms, (MIC 12.5-22.3 microg/mL), while only the oil of P. bicalyculata displayed in-vitro cytotoxicity to MCF-7 (human breast tumor) and MDA-MB-468 (human breast tumor) cells. The present investigation may be the first of its kind for the evaluation of the volatile oil constituents of the studied plants.     

Senna occidentalis (L.) Link and Senna hirsuta (L.) H. S. Irwin & Barneby: constituents of fruit essential oils and antimicrobial activity

Senna occidentalis and S. hirsuta are mostly gathered from the wild for medicinal use and have a disagreeable odour when crushed. The volatile oils isolated from fresh fruits of S. occidentalis and S. hirsuta were subjected to gas chromatography (GC), gas chromatography-mass spectrometry (GC-MS) and antimicrobial assays. GC and GC-MS analyses permitted the identification of 58 constituents. S. occidentalis oil was dominated by cyperene (10.8%), β-caryophyllene (10.4%), limonene (8.0%) and caryophyllene oxide (6.8%). The main components of S. hirsuta fruit oil were benzyl benzoate (24.7%), τ-cadinol (18.9%), 2,5-dimethoxy-p-cymene (14.6%) and β-caryophyllene (5.1%). S. occidentalis fruit oil exhibited better antimicrobial activity (MIC 78–312 μg/mL) against Escherichia coli, Staphylococcus aureus, Bacillus subtilis and Aspergillus niger compared with S. hirsuta oil. The compositions and the activities of the fruit essential oils of S. occidentalis and S. hirsuta are reported for the first time.