Interaction of heparin and tetraarginine in capillary electrophoresis: Implication for analytical applications

Interactions between heparin and tetraarginine in an acidic background electrolyte were investigated in capillary electrophoresis. The results showed that tetraarginine and heparin form a stable complex that migrates toward the anode immediately after coming into contact. When a zone of tetraarginine at a mg/mL concentration level passes through a zone of heparin at a μg/mL concentration level, tetraarginine is gradually removed by the formation of the complex that migrates in the opposite direction, thereby decreasing the tetraarginine peak area. The variation of the tetraarginine peak area as a function of the unfractionated heparin concentration was linear within the range 2–20 μg/mL, which enables us to detect and determine heparin concentrations undetectable with a UV detector. The same behavior was confirmed for low molecular weight heparin.     

An Enolate-Structure-Enabled Anionic Cascade Cyclization Reaction: Easy Access to Complex Scaffolds with Contiguous Six-, Five-, and Four-Membered Rings

Catalyst-free addition of ketone enolate to non-activated multiple C−C bonds involves non-complementary reaction partners and typically requires super-basic conditions. On the other hand, highly aggregated or solvated enolates are not reactive enough to undergo direct addition to alkenes or alkynes. Herein, we report a new anionic cascade reaction for one-step assembly of intriguing molecular scaffolds possessing contiguous six-, five-, and four-membered rings, representing a formal [2+2] enol–allene cycloaddition. Reaction proceeds under very mild conditions and with excellent diastereoselectivity. Deeper mechanistic and computational studies revealed unusually slow proton transfer phenomenon in cyclic ketone intermediate and explained peculiar stereochemical outcome.     

Unexpected reactivity of the burgess reagent with thiols: synthesis of symmetrical disulfides

Reaction of the Burgess reagent with a series of aliphatic and aromatic thiols led to the corresponding symmetrical disulfides in high yields. No olefins were detected in the reactions of aliphatic thiols.     

An improved understanding of the reaction of bis(bromomethyl)quinoxaline 1-N-oxides with amines using substituent effects

The reaction of bis(bromomethyl)quinoxaline N-oxides with amines is interesting from a reaction mechanism perspective and due to the reported biological activity of compounds in this general class. The complex mechanism of this reaction (particularly in the case of primary amines) is complicated further when C6 or C7 substituted mono-N-oxides are considered. In this study, the synthesis and subsequent characterization of a series of 2,3-bis(bromomethyl)quinoxaline 1-N-oxides is reported. Experimental and computational evidence is used to show that the observed product ratios from the reaction with diethylamine reflect the influence of both the C6/C7 substituent and the N-oxide functional group on the initial nucleophilic substitution reaction.     

Synthetic study toward 17-thiasteroids: synthesis of the 1-thiahydrinden-5-one subunit using a new annulation procedure and investigation of its reduction

The enantioselective syntheses of ketones 6 and 7 featuring the CD subunit of 17-thiasteroid are described. The key bicyclic 1-thiahydrindenone (S)-5 was assembled in three steps from Michael adduct (S)-12 via β-keto ester 15 using a one-pot sequential process involving cleavage of both the ketal group and the tert-butyl ester group, decarboxylation, and finally intramolecular aldol condensation. Hydridoalkyl cuprate-induced conjugate reduction of 1-thiahydrindenone (S)-5 and its corresponding sulfone (S)-23 gave 1-thiahydrindanones 6 and 7, respectively, which display unexpectedly the unnatural cis-ring junctions.     

Inner balance of symmetric designs

A triple array is a row-column design which carries two balanced incomplete block designs (BIBDs) as substructures. McSorley et al. (Des Codes Cryptogr 35: 21–45, 2005), Section 8, gave one example of a triple array that also carries a third BIBD, formed by its row-column intersections. This triple array was said to be balanced for intersection, and they made a search for more such triple arrays among all potential parameter sets up to some limit. No more examples were found, but some candidates with suitable parameters were suggested. We define the notion of an inner design with respect to a block for a symmetric BIBD and present criteria for when this inner design can be balanced. As triple arrays in the canonical case correspond to SBIBDs, this in turn yields new existence criteria for triple arrays balanced for intersection. In particular, we prove that the residual design of the related SBIBD with respect to the defining block must be quasi-symmetric, and give necessary and sufficient conditions on the intersection numbers. This, together with our parameter bounds enable us to exclude the suggested triple array candidates in McSorley et al. (Des Codes Cryptogr 35: 21–45, 2005) and many others in a wide search. Further we investigate the existence of SBIBDs whose inner designs are balanced with respect to every block. We show as a key result that such SBIBDs must possess the quasi-3 property, and we answer the existence question for all known classes of these designs.     

Periodic nanostructures self-formed on silicon and silicon carbide by femtosecond laser irradiation

Laser-induced periodic surface structures (LIPSS) were formed on Si and SiC surfaces by irradiations with femtosecond laser pulses in air. Different kinds of self-organized structures appeared on Si and SiC at laser fluences slightly higher than the damage threshold, which was measured by confocal laser scanning microscope. The characteristic spatial periodicity of every observed structure was estimated reading the peak values of the 2D Fourier transform power spectra obtained from SEM images. The evolution of the spatial periodicity was finally studied with respect to both the laser fluence and the number of laser pulses. As already observed for metals, the behavior of the spatial periodicity on laser fluence can be related to the parametric decay of laser light into surface plasma waves. Our results suggest a wide applicability of the parametric decay model on different materials, making the model a useful tool in view of different applications of LIPSS.     

Diophantine approximation of the orbit of 1 in the dynamical system of beta expansions

We consider the distribution of the orbits of the number 1 under the $\beta $ -transformations $T_\beta $ as $\beta $ varies. Mainly, the size of the set of $\beta >1$ for which a given point can be well approximated by the orbit of 1 is measured by its Hausdorff dimension. The dimension of the following set $E\big (\{\ell _n\}_{n\ge 1}, x_0\big )=\Big \{\,\beta >1: |T^n_{\beta }1-x_0|<\beta ^{-\ell _n}, \hbox { for infinitely many}, \, n\in \mathbb{N }\,\Big \}$ is determined, where $x_0$ is a given point in $[0,1]$ and $\{\ell _n\}_{n\ge 1}$ is a sequence of integers tending to infinity as $n\rightarrow \infty $ . For the proof of this result, the notion of the recurrence time of a word in symbolic space is introduced to characterise the lengths and the distribution of cylinders (the set of $\beta $ with a common prefix in the expansion of 1) in the parameter space $\{\,\beta \in \mathbb{R }: \beta >1\,\}$ .     

Introducing cost-plus-loss analysis into a hierarchical forestry planning environment

Cost-plus-loss analysis of data for forestry planning has often been carried out for highly simplified planning situations. In this study, we suggest an advance in the cost-plus-loss methodology that aims to capture the hierarchical structure and iterative nature of planning by the large forest owner. The simulation system that is developed to simulate the planning process of the forest owner includes the tactical and operational levels of a continuous planning process. The system is characterized by annual re-planning of the tactical plan with a planning horizon of ten year and with the option to reassess data for selected stands before operational planning. Operational planning is done with a planning horizon of two years and the first year of the plan is considered to have been executed before moving the planning process one year forward. The annual cycle is repeated 10 times, simulating decisions made over a ten-year time horizon. The optimizing planning models of the system consider wood flow requirements, available harvest resources, seasonal variation of ground conditions and spatiality. The data used are evaluated according to standard procedures in cost-plus-loss analysis. Results from a test case indicate high decision losses when planning at both levels is based on the type of data prevalent in the stand databases of Swedish companies. The losses can be reduced substantially if higher-quality data are introduced before operational planning. In summary, the results indicate that the method makes it possible to analyze where in the planning process one needs better data and their value.     

Analytical one-dimensional model for laser-induced ultrasound in planar optically absorbing layer

Ultrasound generated by means of laser-based photoacoustic principles are in common use today and applications can be found both in biomedical diagnostics, non-destructive testing and materials characterisation. For certain measurement applications it could be beneficial to shape the generated ultrasound regarding spectral properties and temporal profile. To address this, we studied the generation and propagation of laser-induced ultrasound in a planar, layered structure. We derived an analytical expression for the induced pressure wave, including different physical and optical properties of each layer. A Laplace transform approach was employed in analytically solving the resulting set of photoacoustic wave equations. The results correspond to simulations and were compared to experimental results. To enable the comparison between recorded voltage from the experiments and the calculated pressure we employed a system identification procedure based on physical properties of the ultrasonic transducer to convert the calculated acoustic pressure to voltages. We found reasonable agreement between experimentally obtained voltages and the voltages determined from the calculated acoustic pressure, for the samples studied. The system identification procedure was found to be unstable, however, possibly from violations of material isotropy assumptions by film adhesives and coatings in the experiment. The presented analytical model can serve as a basis when addressing the inverse problem of shaping an acoustic pulse from absorption of a laser pulse in a planar layered structure of elastic materials.