Molecular Lesion Spectra as Radiation Signatures

It is suggested that the distribution of DNA molecular lesions (i.e., molecular lesion spectrum. MLS) produced by a particular electromagnetic radiation characterizes that radiation, and that these distributions may serve as radiation signatures. These signatures can have the advantages of (1) high fidelity, (2) persistence times at least ten orders of magnitude greater than track structures, and (3) a space-time cellular position which is approximately half way between initial insult and ultimate biological dysfunction. Spectra are presented for 405nm, 254nm and γ-ray radiations. These MLS's are visually distinctive. Comparable data bases for most other radiations, particulate and electromagnetic, are generally incomplete. We propose the application of adaptive feature recognition and classification techniques to the extraction of radiation signatures for such incomplete data sets. In this work, however, such an application is restricted to quantitation of the degree of orthogonality of the three patterns (i.e., MLS's) for 405nm, 254nm and γ-rays.     

Electronic spectroscopy of highly polar aromatics. X. Luminescence of the fluorobenzonitriles

The absorption and emission spectra of the three isomeric fluorobenzonitriles have been investigated. Quantum yields and decay lifetimes are reported for both fluorescence and phosphorescence processes. Kinetic parameters for energy-depletive processes have been generated and it is shown that this weakly polar subset of D-?-A molecules exhibits most of the characteristics which are peculiar to highly polar isomeric D-?-A triads.     

Photoelectron spectroscopy of carbonyls. Ionization assignments

Photoelectron spectroscopic data are reported for a variety of mono-, di-, and tricarbonyls. Band identifications based on correlative arguments are given. Those experimental effects found useful in identifying the nature of the various ionization bands are specified.     

Stoichiometric generation of magnesium homoenolate equivalents from acyltrimethylsilanes. Synthesis of 1,6-diketone derivatives

Treatment of various acyltrimethylsilanes with vinylmagnesium bromide has allowed a stoichiometric generation of the corresponding 3-(trimethyl-siloxy)allylmagnesiums, which, in the presence of copper(I) trimethylsilyl-acetylide, undergo conjugate addition to several enones to afford the corresponding 1,6-diketone derivatives in good yields.     

Morphological control of ZnO nanostructures on silicon substrates

ZnO nanostructures are grown on Au-catalyzed Si substrates by vapour phase transport between 800 and 1150 C. Nanostructures grown at 800 C are mainly rod-like in structure with diameters of <200 nm. Increasing growth temperature yields combination growth modes with 2D structures (nanowalls/nanosheets) connecting 1D nanorods at intermediate temperatures and a 3D growth mode of foam-like appearance at the highest temperatures. The present work indicates that it may be possible to systematically control the morphology of ZnO nanostructures by varying the growth temperature.     

ZnO nanostructured thin films grown by pulsed laser deposition in mixed O2 / Ar background gas

We report on the properties of ZnO nanostructured thin films grown on either bare or gold patterned a-plane sapphire substrates. The pulsed laser deposition technique was used to deposit all the films at a temperature of 700 C in a mixture of oxygen and argon under a total pressure of 35 Pa. SEM surface characterizations typically showed pyramidal nanostructures with hexagonal symmetry and a coverage density strongly dependent on the O₂ partial pressure. For the patterned samples, wall-like structures of nanoneedles were observed. For all samples, x-ray diffraction results confirmed the high crystalline quality of the nanostructures, with the rocking curve widths of the (0002) reflection as low as 0.09. Similarly, photoluminescence results at room temperature testified to the high optical quality of the material.     

Electroanalysis Using Differential Pulse Methods at a Microelectrode

This communication characterises the differential pulse voltammetric response of ultramicroelectrodes in connection with two different models.     

Long-range electronic interactions in androstanediones

The results of MNDO SCF MO calculations on 5α-androstane (1), androstan-3-one (2), androstan-16-one (3), androstan-17-one (4), androstane-3,16-dione (5), and androstane-3,17-dione (6) and the experimental ¹³C-NMR chemical shifts observed in various solvents (C₆D₁₂, CDCl₃, CD₃CO₂D, CD₂Cl₂, CD₃COCD₃, CD₃OD, CD₃CN) were used to assess the nature of long-range interactions between 3,16- and 3,17-carbonyl groups in androstanediones. The ¹³C-NMR results appear to confirm the proposition that the interactions in androstane-3,16-dione are stronger. © 1997 John Wiley & Sons, Inc. Int J Quant Chem 63: 797–803, 1997     

Development of One-Step Non-Solvent Extraction and Sensitive UHPLC-MS/MS Method for Assessment of N-(n-Butyl) Thiophosphoric Triamide (NBPT) and N-(n-Butyl) Phosphoric Triamide (NBPTo) in Milk

N-(n-butyl) thiophosphoric triamide (NBPT) is a urease inhibitor utilised in urea-based fertilizers. In Ireland, fertilizer treated with NBPT is applied to pasture to mitigate both ammonia and nitrous oxide emissions, but concerns arise as to the potential for residues in milk products. A quick ultrafiltration extraction and ultra-high performance liquid chromatography coupled with mass spectrometry triple quadrupole (UHPLC-MS/MS) quantitation method was developed and validated in this study. The method was applied in the analysis of samples collected from a field study investigating potential transfer of NBPT residues into milk. NBPT and NBPTo residues, were extracted from fortified milk samples and analysed on a UHPLC-MS/MS with recoveries ranging from 74 to 114%. Validation of the UHPLC-MS/MS method at low (0.0020 mg kg⁻¹) and high (0.0250 mg kg⁻¹) concentration levels in line with SANTE/12682/2019 showed overall trueness in the range of 99 to 104% and precision between 1 and 10%, RSD for both compounds. The limit of quantitation (LOQ) was 0.0020 mg kg⁻¹ and other tested parameters (linearity, sensitivity, specificity, matrix effect, robustness, etc.) satisfied acceptance criteria. Stability assessment using spiked samples revealed the compounds were stable in raw and pasteurised milk for 4 weeks at –80 °C storage temperature. Maintaining samples at pH 8.5–9.0 further improved stability. Analysis of 516 milk samples from the field study found that NBPT and NBPTo concentrations were below the LOQ of 0.0020 mg kg⁻¹, thus suggesting very low risk of residues occurring in the milk. The method developed is quick, robust, and sensitive. The method is deemed fit-for-purpose for the simultaneous determination of NBPT and NBPTo in milk.