Rapid detection of <Emphasis Type="Italic">Aspergillus flavus</Emphasis> in rice using biofunctionalized carbon nanotube field effect transistors

Popularity of new psychoactive substances, known as legal highs or herbal highs, is continuously growing. These products are typically sold via internet and in so-called head shops. The aim of this study was to identify active ingredients of herbal highs and to compare their chemical composition. Twenty-nine various products seized by the police in one of the “head shops” were analysed. Herbal mixtures (0.2 g) were prepared by ultrasonic-assisted extraction with 2.0 ml of ethanol for 2 h. The extracts were analysed by gas chromatography coupled to mass spectrometry (GC/MS). The main active compounds of the herbal mixtures were synthetic cannabinoids: JWH-018, JWH-073 and cannabicyclohexanol (CP-47,497-C8-homolog). Their content differed between the products; some contained only one cannabinoid whereas the others contained two or more. Cluster analysis and principal component analysis revealed that chemical composition of many products was very similar. The similarity was connected with their flavour and not the common name. This statement was true for the synthetic cannabinoids, other potential agonists of cannabinoid receptors (amides of fatty acids) and ingredients of natural origin and confirms that herbal highs are a threat to human health because the purchaser has no information on their real composition.     

Fluoride removal from water by chitosan derivatives and composites: A review

Fluoride is an essential element, indispensable for maintenance of dental health. Nevertheless, fluoride concentrations in drinking water above 1.5 mg L⁻¹ may be detrimental to human health. Many methods have been developed for removing excessive fluoride from drinking water, adsorption seems to be an effective, environmentally friendly and economical one. Since the sorption capacity of fluoride below 2 mg L⁻¹ on most conventional adsorbents is not satisfactory, much effort has been devoted to develop new and cost-effective fluoride adsorbents. This review reports the recent developments in the F⁻ removal in water treatment, using chitosan derivatives and composites in order to provide useful information about the different technologies. When possibly the adsorption capacity of chitosan derivatives and composites under different experimental conditions is reported to help to compare the efficacy of the fluoride removal process. A comparison with the adsorption capacity of other low cost adsorbents is also tabled.     

Probing vibrational wave packets in molecular excited states

A time-dependent theoretical method is used to describe a UV pump?CUV probe strategy to trace, at a femtosecond time scale, the motion of vibrational wave packets created in excited states of the hydrogen molecule by measuring single ionization probabilities. We use a spectral method to solve the time-dependent Schr?dinger equation in full dimensionality, including correlation and all electronic and vibrational degrees of freedom. A pump pulse initially creates a vibrational wave packet in the intermediate electronic excited states of $\hbox{H}_2$ . The frequency of the probe is chosen to ionize the target leaving the ion in a bound vibrational state. By varying the time delay between pulses, non-dissociative single ionization is enhanced or suppressed. Energy differential ionization probabilities are reported and compared with a model based on the Franck?CCondon approximation.     

On the stability and lifetime of GaO2+ in the gas phase

The electronic structure, stability, and lifetime of GaO²⁺ have been investigated using high-level ab initio calculations. The potential energy curves have been calculated at the CCSD(T)/aug-cc-pV5Z and at the MS-CASPT2/ANO-RCC levels of theory. Lifetimes were evaluated using the Exterior Complex Scaling (ECS) method and B-spline basis functions. Our calculations show that GaO²⁺ is a metastable species in the gas phase, since the diatomic dication, in its ground state, lies 97.1?kcal/mol above the Ga⁺ (¹S)?+?O⁺ (⁴S) dissociation limit. However, the energy barrier that has to be overcome to reach this limit is 3?kcal/mol high so that five vibrational resonances can be accommodated between the bottom of the well and the top of the barrier. The evaluated lifetimes vary from hundreds of femtoseconds to approximately 1?s, so at least two of them have long enough lifetimes (1?s and 91???s) to be detected using mass spectrometry techniques, in agreement with the experimental evidence. In the experiment (Fiser et al. in Eur J Mass Spectrom 15:315?C324, 2009), GaO²⁺ was observed for an ion flight time of about ~12???s through a magnetic-sector mass spectrometer and unambiguously identified by its isotopic abundance. Our results also show that isotopic effects on the resonances?? energies and on their lifetimes, when ⁷⁰Ga is replaced by ⁶⁹Ga or ⁷¹Ga, are very small (~0.1 and ~1%, respectively), reflecting the large mass of the system.     

Structural evidence of anomeric effects in the anesthetic isoflurane

The conformational and structural properties of the inhalational anesthetic isoflurane (1-chloro-2,2,2-trifluoroethyl difluoromethyl ether) have been probed in a supersonic jet expansion using Fourier-transform microwave (FT-MW) spectroscopy. Two conformers of the isolated molecule were identified from the rotational spectrum of the parent and several (37)Cl and (13)C isotopologues detected in natural abundance. The two most stable structures of isoflurane are characterized by an anti carbon skeleton (τ(C(1)-C(2)-O-C(3)) = 137.8(11)° or 167.4(19)°), differing in the trans (AT) or gauche (AG) orientation of the difluoromethyl group. The conformational abundances in the jet were estimated from relative intensity measurements as (AT)/(AG) ≈ 3:1. The structural preferences of the molecule have been rationalized with supporting ab initio calculations and natural-bond-orbital (NBO) analysis, which suggest that the molecule is stabilized by hyperconjugative effects. The NBO analysis of donor-acceptor (LP → σ*) interactions showed that these stereoelectronic effects decrease from the AT to AG conformations, so the conformational preferences can be accounted for in terms of the generalized anomeric effect.     

Improving Physical Properties via C?H Oxidation: Chemical and Enzymatic Approaches

Physicochemical properties constitute a key factor for the success of a drug candidate. Whereas many strategies to improve the physicochemical properties of small heterocycle‐type leads exist, complex hydrocarbon skeletons are more challenging to derivatize because of the absence of functional groups. A variety of C H oxidation methods have been explored on the betulin skeleton to improve the solubility of this very bioactive, yet poorly water‐soluble, natural product. Capitalizing on the innate reactivity of the molecule, as well as the few molecular handles present on the core, allowed oxidations at different positions across the pentacyclic structure. Enzymatic oxidations afforded several orthogonal oxidations to chemical methods. Solubility measurements showed an enhancement for many of the synthesized compounds.     

Detectivity of the photosensors: A reevaluation

Important parameters of the photosensors such as Noise Equivalent Power (NEP) and detectivity depend upon the magnitude of the signal to noise ratio. Recent improvements in the techniques of measurement in digitized form permit to process noise statistically with a suitable procedure and increase the detection capability more than expected from the conventional definition.     

Strategies for the synthesis of bi- and triarylic materials starting from commercially available phenols

A series of arylstannanes have been synthesized, through an S_RN1 mechanism, in good to excellent yields (74%-99%) by the photostimulated reaction of trimethyl stannyl ion with substrates supporting different nucleofugal groups. The arylstannanes thus obtained were suitable intermediates for Stille cross-coupling reactions leading to asymmetric bi- and triaryl compounds in acceptable global yields. An attractive feature of this route is that simple commercially available benzenediols, chloro- and methoxy phenols might be useful starting substrates, leading the latter to higher global yields of products in fewer steps. The strategies proposed open a broad synthetic tool.