The sense of smell,its signalling pathways,and the dichotomy of cilia and microvilli in olfactory sensory cells

Smell is often regarded as an ancillary perception in primates, who seem so dominated by their sense of vision. In this paper, we will portray some aspects of the significance of olfaction to human life and speculate on what evolutionary factors contribute to keeping it alive. We then outline the functional architecture of olfactory sensory neurons and their signal transduction pathways, which are the primary detectors that render olfactory perception possible. Throughout the phylogenetic tree, olfactory neurons, at their apical tip, are either decorated with cilia or with microvilli. The significance of this dichotomy is unknown. It is generally assumed that mammalian olfactory neurons are of the ciliary type only. The existence of so-called olfactory microvillar cells in mammals, however, is well documented, but their nature remains unclear and their function orphaned. This paper discusses the possibility, that in the main olfactory epithelium of mammals ciliated and microvillar sensory cells exist concurrently. We review evidence related to this hypothesis and ask, what function olfactory microvillar cells might have and what signalling mechanisms they use.     

Analytic modeling of the angular sensitivity function and modulation transfer function of ultrathin multichannel imaging systems

We propose what we believe to be a novel, refined model of the angular sensitivity function of artificial apposition compound eyes. Compared with the formerly used Gaussian approximation that was derived for natural compound eyes, our model is better suited to describe the resolution capacity of artificial compound eyes accounting for the cylindrical sensitivity function of technical receptors. It is shown that this analytic model is valid over a broad range of parameters of the optical system, which was not fulfilled by one of the previous models. Finally, an analytic approach is used to derive the modulation transfer function of these multichannel imaging systems.     

Fast Analytical Temperature Rising Elution Fractionation (ATREF) Method

Conventional analytical temperature rising elution fractionation (ATREF) is performed using slowly crystallized polymers in about 16 h. In this work, we developed a fast ATREF method in which the polymer sample is directly injected on the column at room temperature, thus reducing the analysis time to about 1 h. The method was tested using four metallocene polyethylenes with unimodal short chain branching distributions and different densities, previously analyzed by ATREF using a cooling rate of 0.1°C/min. The obtained results demonstrate that the fast ATREF method is very effective and accurate in evaluating short chain branching distribution for polyolefins having unimodal distributions.     

An Easy Route to (Hetero)arylboronic Acids

An unprecedented spontaneous reactivity between diazonium salts and diboronic acid has been unveiled, leading to a versatile arylboronic acid synthesis directly from (hetero)arylamines. This fast reaction (35 min overall) tolerates a wide range of functional groups and is carried out under very mild conditions. The radical nature of the reaction mechanism has been investigated.     

On the Synthesis,Characterization and Reactivity of N‐Heteroaryl–Boryl Radicals,a New Radical Class Based on Five‐Membered Ring Ligands

The synthesis and physical characterization of a new class of N‐heterocycle–boryl radicals is presented, based on five membered ring ligands with a N(sp²) complexation site. These pyrazole–boranes and pyrazaboles exhibit a low bond dissociation energy (BDE; B?H) and accordingly excellent hydrogen transfer properties. Most importantly, a high modulation of the BDE(B?H) by the fine tuning of the N‐heterocyclic ligand was obtained in this series and could be correlated with the spin density on the boron atom of the corresponding radical. The reactivity of the latter for small molecule chemistry has been studied through the determination of several reaction rate constants corresponding to addition to alkenes and alkynes, addition to O₂, oxidation by iodonium salts and halogen abstraction from alkyl halides. Two selected applications of N‐heterocycle–boryl radicals are also proposed herein, for radical polymerization and for radical dehalogenation reactions.     

Tuning Lanthanide Reactivity Towards Small Molecules with Electron‐Rich Siloxide Ligands

The synthesis, structure, and reactivity of stable homoleptic heterometallic LnL₄K₂ complexes of divalent lanthanide ions with electron‐rich tris(tert‐butoxy)siloxide ligands are reported. The [Ln(OSi(OtBu)₃)₄K₂] complexes (Ln=Eu, Yb) are stable at room temperature, but they promote the reduction of azobenzene to yield the KPhNNPh radical anion as well as the reductive cleavage of CS₂ to yield CS₃^2? as the major product. The Eu^III complex of the radical anion PhNNPh is structurally characterized. Moreover, [Yb(OSi(OtBu)₃)₄K₂] can reduce CO₂ at room temperature. Release of the reduction products in D₂O shows the quantitative formation of both oxalate and carbonate in a 1:2.2 ratio. The bulky siloxide ligands enforce the labile binding of the reduction products providing the opportunity to establish a closed synthetic cycle for the Yb^II‐mediated CO₂ reduction. These studies show that the presence of four electron‐rich siloxide ligands renders their Eu^II and Yb^II complexes highly reactive.     

Phenanthrene‐Fused‐Quinoxaline as a Key Building Block for Highly Efficient and Stable Sensitizers in Copper‐Electrolyte‐Based Dye‐Sensitized Solar Cells

Dye‐sensitized solar cells (DSSCs) based on Cu^II/I bipyridyl or phenanthroline complexes as redox shuttles have achieved very high open‐circuit voltages (V_OC, more than 1 V). However, their short‐circuit photocurrent density (J_SC) has remained modest. Increasing the J_SC is expected to extend the spectral response of sensitizers to the red or NIR region while maintaining efficient electron injection in the mesoscopic TiO₂ film and fast regeneration by the Cu^I complex. Herein, we report two new D‐A‐π‐A‐featured sensitizers termed HY63 and HY64 , which employ benzothiadiazole (BT) or phenanthrene‐fused‐quinoxaline (PFQ), respectively, as the auxiliary electron‐withdrawing acceptor moiety. Despite their very similar energy levels and absorption onsets, HY64 ‐based DSSCs outperform their HY63 counterparts, achieving a power conversion efficiency (PCE) of 12.5 %. PFQ is superior to BT in reducing charge recombination resulting in the near‐quantitative collection of photogenerated charge carriers.     

Air‐Stable Oxyallyl Patterns and a Switchable N‐Heterocyclic Carbene

Oxyallyl derivatives are typically elusive compounds. Even recently reported “stabilized” 1,3‐diaminooxyallyl species are still highly reactive and have short lifetimes at room temperature. Herein, we report the synthesis and preliminary study of mesoionic pyrimidine derivatives that feature 1,3‐bis(dimethylamino)oxyallyl patterns with an unprecedented level of stabilization. The latter are not only insensitive towards air and moisture, but they are also compatible with the formation of an ancillary stable N‐heterocyclic carbene moiety. As the oxyallyl pattern is proton‐responsive, it allows the reversible switching of the electronic properties of the carbene, as a ligand.     

Method development and validation for the determination of biogenic amines in soy sauce using supercritical fluid chromatography coupled with single quadrupole mass spectrometry

Biogenic amines have been reported in many foods such as fish, meat, and soy sauce. The consumption of foods containing high concentrations of biogenic amines has been associated with health hazards. In this study, a green and efficient method using supercritical fluid chromatography coupled with single quadrupole mass spectrometry was developed for determination of biogenic amines in soy sauce. The chromatographic and mass spectrometry conditions were systematically optimized in terms of selectivity and peak shape. Nine biogenic amines were well separated within 25 min on a Cosmosil 5HP column using 5% (v/v) water and 0.2% (v/v) ammonia solution in methanol as mobile phase additives at a backpressure of 120 bar and temperature of 40°C. The established method was fully validated regarding the linearity, sensitivity, precision, and accuracy. The limits of detection and limits of quantification ranged from 0.03 to 10.50 μg/mL and 0.10 to 23.1 μg/mL, respectively. The relative standard deviations for intra‐ and interday precisions were all lower than 9.36% and the recoveries ranged from 75.82 to 99.63% and 80.10 to 99.89% for two levels of standards spiked in soy sauce, respectively. Finally, the established method was successfully applied to the quantitative analysis of biogenic amines in soy sauce.