ℓ-group homomorphisms between reduced archimedean f-rings

Let A and B be reduced archimedean f-rings, A with identity e; let $A\,\mathop \to \limits^\gamma\,BLet A and B be reduced archimedean f-rings, A with identity e; let A \mathop ? ^g BA\,\mathop \to \limits^\gamma\,B be an ℓ-group homomorphism, and set w = γ (e). We show (with some vagaries of phrasing here) (1) γ = w·ρ for a canonical ℓ-ring homomorphism A \mathop ? ^r B (w)A\,\mathop \to \limits^\rho\,B (w), where B (w) is an extension of B in which w is a von Neumann regular element, and (2) for X _A ,X _B canonical representation spaces for A, B, γ is realized via composition with a unique partially defined continuous function from X _B to X _A .     

The role of water H-bond imbalances in B-DNA substate transitions and peptide recognition revealed by time-resolved FTIR spectroscopy

The conformational substates B(I) and B(II) of the phosphodiester backbone in B-DNA are thought to contribute to DNA flexibility and protein recognition. We have studied by rapid scan FTIR spectroscopy the isothermal B(I)-B(II) transition on its intrinsic time scale. Correlation analysis of IR absorption changes occurring within seconds after a reversible incremental growth of the DNA hydration shell identifies water populations w(1) (PO(2)(-)-bound) and w(2) (non-PO(2)(-)-bound) exhibiting weaker and stronger H-bonds, respectively, than those dominating in bulk water. The B(II) substate is stabilized by w(2). The water H-bond imbalance of 3-4 kJ mol(-1) is equalized at little enthalpic cost upon formation of a contiguous water network (at 12-14 H(2)O molecules per DNA phosphate) of reduced ν(OH) bandwidth. In this state, hydration water cooperatively stabilizes the B(I) conformer via the entropically favored replacement of w(2)-DNA interactions by additional w(2)-water contacts, rather than binding to B(I)-specific hydration sites. Such water rearrangements contribute to the recognition of DNA by indolicidin, an antimicrobial 13-mer peptide from bovine neutrophils which, despite little intrinsic structure, preferentially binds to the B(I) conformer in a water-mediated induced fit. The FTIR spectra resolve sequential steps leading from PO(2)(-)-solvation to substate transition and eventually to base stacking changes in the complex. In combination with CD-spectral titrations, the data indicate that, in the absence of a bulk aqueous phase, as in molecular crowded environments, water relocation within the DNA hydration shell allows for entropic contributions similar to those assigned to water upon DNA ligand recognition in solution.     

Transient absorption induced by a picosecond electron pulse in the fused silica windows of an optical cell

The transient absorption induced by picosecond pulse radiolysis in the windows of a fused silica optical cell is investigated with pump probe techniques in the UV and the visible range. After excitation with an electron pulse of 7 MeV and an effective duration of around 10 ps the absorbance changes during relaxation are recorded up to nanoseconds with a supercontinuum and a single wavelength probe at 263 nm. The complex spectral signatures and kinetics of the empty cell are set into relation with the transient absorption of water radiolysis. Special care is taken to assure equal irradiation conditions for the comparative measurements over the large spectral range. The results reveal clearly that the transient absorption induced in the fused silica cell is not negligible. The transient signals due to the cell should be considered in picosecond pulse radiolysis of solutions in order to avoid important errors on the time dependent yield of transient species, particularly of those absorbing in the UV.     

Synthesis of Cyclic Polyamines by Enzymatic Generation of an Amino Aldehyde In Situ

Multifunctional polycationic polyamines, for example, used in drug and gene delivery, have product range limitations in their synthesis methods. Here, we synthesize a polyamine by forming a self‐assembling amino aldehyde from the corresponding amino alcohol with horse liver alcohol dehydrogenase (HLADH), followed by reduction. Circular polyamines were synthesized from 3‐amino‐propan‐1‐ol as starting material, analogous to cyclic polyamines formed from azetidin. The product had an isolated yield of 89.7% or 15.3 g L⁻¹. The predicted range of possible polyamine products by this method is broad since many amino alcohols are putative substrates for HLADH. The enzyme also had activity for 2‐amino‐propan‐1‐ol and 2‐amino‐2‐phenyl‐ethanol, for which the enantioselectivity was 330 (S) and 32 (R), respectively.     

Photoluminescence of Uranium(VI): Quenching Mechanism and Role of Uranium(V)

The photoluminescence of uranium(VI) is observed typically in the wavelength range 400–650 nm with the lifetime of several hundreds μs and is known to be quenched in the presence of various halide ions (case A) or alcohols (case B). Here, we show by density functional theory (DFT) calculations that the quenching involves an intermediate triplet excited state that exhibits uranium(V) character. The DFT results are consistent with previous experimental findings suggesting the presence of photoexcited uranium(V) radical pair during the quenching process. In the ground state of uranyl(VI) halides, the ligand contributions to the highest occupied molecular orbitals increase with the atomic number (Z) of halide ion allowing larger ligand‐to‐metal charge transfer (LMCT) between uranium and the halide ion. Consequently, a larger quenching effect is expected as Z increases. The quenching mechanism is essentially the same in cases A and B, and is driven by an electron transfer from the quencher to the UO₂²⁺ entity. The relative energetic stabilities of the triplet excited state define the “fate” of uranium, so that in case A uranium(V) is oxidized back to uranium(VI), while in case B uranium remains as pentavalent.     

Microbial quality evaluation and effective decontamination of nutraceutically valued lotus seeds by electron beams and gamma irradiation

Lotus seeds are nutraceutically valued natural plant produce, which succumbs to microbial contamination, predominantly to toxigenic moulds. Results of the present study revealed seed coat portion to harbor higher proportion of microbial load, particularly fungi than cotyledon portion. Among the mycotoxins analyzed, aflatoxins (B₁, B₂, G₁ and G₂) were below detectable limits, while the seeds were devoid of Ochratoxin-A (OTA). Application of different doses of electron beam and gamma irradiation (0, 2.5, 5, 7.5, 10, 15 and 30 kGy) for decontamination purpose revealed significant dose-dependent decrease in the fungal contaminants (P<0.05). However, the contaminant yeasts could survive up to 10 kGy dose, which could be completely eliminated at 15 kGy. From the results obtained, a dose range between 10 and 15 kGy is recommended for complete decontamination, as these doses have also been shown earlier to have minimal effects on nutritional and functional properties of lotus seeds.     

Fast local searches and updates in bounded universes

Given a bounded universe $\{0,1,\dots ,U?1\}$, we show how to perform predecessor searches in $O(\log \log \mathrm{\Delta })$ expected time, where Δ is the difference between the element being searched for and its predecessor in the structure, while supporting updates in $O(\log \log \mathrm{\Delta })$ expected amortized time, as well. This unifies the results of traditional bounded universe structures (which support predecessor searches in $O(\log \log U)$ time) and hashing (which supports membership queries in $O(1)$ time). We also show how these results can be applied to approximate nearest neighbour queries and range searching.     

Dielectric‐loaded plasmonic waveguide components: Going practical

Surface plasmon propagating modes supported by metal/dielectric interfaces in various configurations can be used for radiation guiding similarly to conventional dielectric waveguides. Plasmonic waveguides offer two attractive features: subdiffraction mode confinement and the presence of conducting elements at the mode‐field maximum. The first feature can be exploited to realize ultrahigh density of nanophotonics components, whereas the second feature enables the development of dynamic components controlling the plasmon propagation with ultralow signals, minimizing heat dissipation in switching elements. While the first feature is yet to be brought close to the domain of practical applications because of high propagation losses, the second one is already being investigated for bringing down power requirements in optical communication systems. In this review, the latest application‐oriented research on radiation modulation and routing using thermo‐optic dielectric‐loaded plasmonic waveguide components integrated with silicon‐based photonic waveguides is overviewed. Their employment under conditions of real telecommunications is addressed, highlighting challenges and perspectives.     

Almost f-maps and almost f-rings

In the beginning of the eighties, Buskes and Holland proved that any archimedean almost f-ring is commutative. One decade later, Steinberg showed that if G and H are ? with H archimedean, then any positive bilinear map G × G ${{\begin{array}{ll} B \\ \rightarrow \end{array}}}$ H such that ${x \wedge y = 0}$ implies B(x, y) = 0 is symmetric. At first sight, the Steinberg Theorem might seem to be a considerable generalization of the Buskes and Holland result. It turns out, surprisingly enough, that these two results are equivalent. The main purpose of this paper is to establish this equivalence. A second objective is to apply the aforementioned Steinberg Theorem to prove that if R is an f-ring with a unit element e and S is an archimedean f-ring, then an ?-homomorphism R ${{{\begin{array}{ll} h \\\rightarrow \end{array}}}}$ S is a ring homomorphism if and only if h(e) is idempotent in S. This extends a well-known result by Huijsmans and de Pagter, who obtained the same conclusion for semiprime f-algebras.     

New DEFT sequences for the acquisition of one-dimensional carbon NMR spectra of small unlabelled molecules

The acquisition time and quality of 1D 13C{1H} spectra can be improved substantially by using a modified driven equilibrium Fourier transform (DEFT) sequence, which is specifically designed to compensate for the effects of B1 inhomogeneity, pulse miscalibration and frequency offsets. The new sequence, called uniform driven equilibrium Fourier transform (UDEFT), returns the carbon magnetization with a high accuracy along its equilibrium position after each transient is complete. Thus, the sequence allows the use of relaxation delays (RD), which are much shorter than the carbon T1 of the molecule, thereby speeding up the acquisition process of 1D 13C{1H} spectra. To achieve this level of performance, UDEFT employs a refocusing element constituted by a composite adiabatic carbon pulse surrounded by two 90 degrees carbon pulses whose phases are designed to compensate for 90 degrees pulse miscalibrations in an MLEV manner (90 degrees+x-tau(FID)-180+y(Adia)-tau-90 degrees+x-180 degrees+x(Adia)). A version of the UDEFT sequence allows recording 1D 13C{1H} spectra devoid of heteronuclear NOE by using a matched adiabatic 1H decoupling scheme where an even number of 180 degrees adiabatic pulses is applied during the UDEFT module. Spectra of a solution of 300 mM camphor that contains some carbon nuclei with very long T1 relaxation times (90 s and 78 s) were acquired with 128 scans in 10 min using a 5 s relaxation delay.