Nuclear analogs of β-lactam antibiotics. 7. The synthesis of 3-thia- and 3-aza-1-dethiaceph-1-em esters

The total synthesis of a 3-thia- and a 3-aza-1-dethiacepham ($\text{9}$ and $\text{16}$) are described. Neither compound possessed antibacterial activity $\text{vs}$$\text{B}$. $\text{subtilis}$. An unsaturated analog, a 3-aza-1-dethiaceph-1-em exhibited weak antibacterial activity.     

Determination of phosphorus in fertilizers by inductively coupled plasma atomic emission spectrometry

An inductively coupled plasma atomic emission spectrometry (ICP-AES) method was developed for the determination of phosphorus in fertilizers. Total phosphorus, direct extraction available phosphorus (EDTA), and water-soluble phosphorus, reported as phosphorus pentoxide (P205), in 15 Magruder check fertilizers were measured by ICP-AES, and the results were compared with those obtained by the AOAC official method. Five analytical wavelengths of phosphorus, 177.499, 178.287, 213.618, 214.914, and 253.565 nm, were tested for the determination of phosphorus in fertilizers, and their detection limits were obtained. Acid effects of perchloric acid and possible matrix effects of aluminum, calcium, magnesium, potassium, and sodium were negligible for phosphorus determination. Wavelength 213.618 nm was the best analytical wavelength for phosphorus determination by all 3 sample preparation methods for the selected Magruder fertilizers. The results demonstrated that the accuracy and precision of the ICP-AES method were comparable with those of the official methods.     

Analysis of amphetamine and methamphetamine as emerging pollutants in wastewater and wastewater-impacted streams

The identification and quantitation of the non-ecstasy amphetamine-type stimulants (ATSs) amphetamine and methamphetamine in lakes, rivers, wastewater treatment plant influents, effluents, and biosolids are reviewed. Neither monitoring nor reporting is required of these ATSs, which are considered emerging pollutants, but they have been identified in the environment. Amphetamine and methamphetamine enter our water supply by human excretion after legal or illegal consumption and via manufacturing in clandestine laboratories. Analytical methodology for sampling, sample preparation, separation, and detection of ATSs is discussed. Reported occurrences of ATSs in the environment and their use in municipal sewage epidemiology are noted. Future research needs that challenge applications of analytical techniques are discussed. The review focuses on research reported from 2004 to 2009.     

Single dibenzoterrylene molecules in naphthalene and 2,3-dimethylnaphthalene crystals: vibronic spectra

Fluorescence excitation spectra of single dibenzoterrylene (DBT) molecules embedded in naphthalene (N) and 2,3-dimethylnaphthalene (2,3-DMN) crystals were studied at 5 K. The frequencies characterizing the vibronic structure of single DBT molecules in an N crystal agree with the theoretical prediction for the isolated DBT molecule. The 'dipolar' disorder encountered in 2,3-DMN crystals leads to a broad distribution of frequencies of the (0,0) lines of single DBT molecules. Moreover, the observed vibronic frequencies and intensities in the spectrum of DBT in 2,3-DMN crystals are slightly different to those in an N crystal. We conclude that the structure of DBT molecules in a 2,3-DMN crystal is disturbed in comparison with isolated DBT and the main change concerns its central tetracene moiety.     

Analysis of amphetamine and methamphetamine in municipal wastewater influent and effluent using weak cation‐exchange SPE and LC‐MS/MS

Amphetamine and methamphetamine are emerging contaminants—those for which no regulations currently require monitoring or public reporting of their presence in our water supply. In this research, a protocol for weak cation‐exchange (WCX) SPE coupled with LC‐MS/MS was developed for determination of emerging contaminants amphetamine and methamphetamine in a complex wastewater matrix. Gradient LC parameters were adjusted to yield baseline separation of methamphetamine from other contaminants. Methamphetamine‐D5 was used as the internal standard (IS) to compensate for sample loss during SPE and for signal loss during MS (matrix effects). Recoveries were 102.1 ± 7.9% and 99.4 ± 4.0% for amphetamine and methamphetamine, respectively, using WCX sorbent. Notably, methamphetamine was determined to be present in wastewater influent at each sampling date tested. Amphetamine was present in wastewater influent on two of four sampling dates. Amphetamine concentrations ranged from undetectable to 86.4 ng/L in influent, but it was undetectable in wastewater effluent. Methamphetamine was detected in influent at concentrations ranging from 27.0–60.3 ng/L. Methamphetamine concentration was reduced but incompletely removed at this facility. Although absent in one post‐UV effluent sample, concentrations of methamphetamine ranged from 10.8–14.8 ng/L.     

On the optimal robust solution of IVPs with noisy information

We investigate the optimal solution of systems of initial-value problems with smooth right-hand side functions f from a Hölder class \(F^{r,\varrho }_{\text {reg}}\), where r ≥ 0 is the number of continuous derivatives of f, and ? ∈ (0, 1] is the Hölder exponent of rth partial derivatives. We consider algorithms that use n evaluations of f, the ith evaluation being corrupted by a noise δ_i of deterministic or random nature. For δ ≥ 0, in the deterministic case the noise δ_i is a bounded vector, ∥δ_i∥≤δ. In the random case, it is a vector-valued random variable bounded in average, (E(∥δ_i∥^q))^1/q ≤ δ, q ∈ [1, + ∞). We point out an algorithm whose L_p error (p ∈ [0, + ∞]) is O(n ^{? (r + ?)} + δ), independently of the noise distribution. We observe that the level n ^{? (r + ?)} + δ cannot be improved in a class of information evaluations and algorithms. For ε > 0, and a certain model of δ-dependent cost, we establish optimal values of n(ε) and δ(ε) that should be used in order to get the error at most ε with minimal cost.     

Vibrational spectra of two BEDT-TTF-based organic conductors: charge order

Infrared and Raman investigations of two phases of bis(ethylenedithio)tetrathiafulvalene (BEDT-TTF) based organic conductors with the same CF₃CF₂SO₃⁻ anion: β′-(BEDT-TTF)₂CF₃CF₂SO₃ and δ′-(BEDT-TTF)₂CF₃CF₂SO₃, are shortly reviewed and compared with the most typical infrared properties of the family of (BEDT-TTF)₂RR′SO₃ organic conductors, where R = SF₅, CF₃, and R′ are CH₂, CF₂, CHF, CHFCF₂, and CH₂CF₂. The role of the molecular structur and spatial organization of the counterions is discussed. Presented at 2-nd International Conference on Functional Materials and Devices, ICFMD 2008, June 16–19, 2008, Kuala Lumpur, Malaysia     

12-hydroxy-1-azaperylene-limiting case of the ESIPT system: enol-keto tautomerization in S0 and S1 states

Absorption, fluorescence, and fluorescence excitation spectra of 12-hydroxy-1-azaperylene (HAP) and 1-azaperylene were studied in n-alkane matrices at 5 K. Two stable tautomers of HAP, each of them in n-nonane embedded in two sites, were identified and attributed to the enol and keto forms. Theoretical calculations of the energy and vibrational structure of the spectra suggest that tautomer A, with the (0, 0) transition energy at 18,980 ± 10 cm(-1) (and 19,060 ± 10 cm(-1) in the high energy site), should be identified as the keto form, whereas tautomer B, with the (0, 0) energy at 19,200 ± 20 cm(-1) (19,290 ± 20 cm(-1)), as the enol form. Observation of absorption and fluorescence of both tautomeric forms and lack of large Stokes shift of fluorescence of the keto form classify HAP as the limiting case of the excited-state intramolecular proton transfer system.     

Reaction of diethylhydroxyborane with trialkylaluminium

The reaction of diethylhydroxyborane with trialkylaluminium has been studied. Trialkylboranes and diethyltriisobutyldialuminium dioxide were isolated and characterized. A two-stage mechanism is proposed for the formation.