Exploiting sp2‐Hybridisation in the Development of Potent 1,5‐α‐l‐Arabinanase Inhibitors

The synthesis of potent inhibitors of GH93 arabinanases as well as a synthesis of a chromogenic substrate to measure GH93 arabinanase activity are described. An insight into the reasons behind the potency of the inhibitors was gained through X‐ray crystallographic analysis of the arabinanase Arb93A from Fusarium graminearum. These compounds lay a foundation for future inhibitor development as well as for the use of the chromogenic substrate in biochemical studies of GH93 arabinanases.     

Conjugation of a Dipicolyl Chelate to Polypeptide Conjugates Increases Binding Affinities for Human Serum Albumin and Survival Times in Human Serum

The affinity for human serum albumin (HSA) of a series of 2–5 kDa peptides covalently linked to 3,5‐bis[[bis(2‐pyridylmethyl)amino]methyl]benzoic acid, a dipicolyl chelator with micromolar affinity for Zn²⁺, was found by surface plasmon resonance to increase in the presence of 1 μm ZnCl₂ at physiological pH. The dependence on polypeptide hydrophobicity was found to be minor, thus suggesting that the conjugates bound to the metal‐binding site and not to the fatty‐acid‐binding site. The affinity of the conjugates increased strongly with the positive charge of the polypeptides, thus implicating the negatively charged protein surface surrounding the metal‐binding site. The survival times of the peptides in human serum were extended as a consequence of stronger binding to HSA, thus suggesting that Zn²⁺‐chelating agents might provide a general route to increased survival time of peptides in serum in therapeutic and diagnostic applications without significantly increasing their molecular weights.     

Synthesis and photochemical reaction of benzo[a]quinoxalino[2,3‐c]phenazine dyes

Novel dyes based on the benzo[a]quinoxalino[2,3‐c]phenazine skeleton and necessary intermediates (benzo[a]phenazine‐5,6‐diones) were synthesized. The heterocyclic dyes and benzo[a]phenazine‐5,6‐diones were characterized using ¹H nuclear magnetic resonance (NMR) spectroscopy and chemical ion (CI) mass spectrometry. Their spectral properties, such as absorption and emission spectra and fluorescence quantum yield, were also measured. Experimental results demonstrated that photolysis of benzo[a]quinoxalino[2,3‐c]phenazine dyes in 2‐propanol and cyclohexene oxide leads to dihydro derivatives. The same product is formed during irradiation of dye/iodonium salt photoredox pairs in monomers. These compounds absorb incident light at longer wavelength and act as in situ sensitizers. Thus, when a composition was irradiated with a xenon lamp through a 395 cutoff filter, higher conversion was achieved than under monochromatic light.     

Determination of Total Antioxidant Capacity of Rapeseed and Its By-Products by a Novel Cerium Oxide Nanoparticle-Based Spectrophotometric Method

The antioxidant capacity (AC) of rapeseed, white flakes, and meal was determined by the novel cerium oxide nanoparticle-based (CeONP) method and a previously described assay based on the formation of silver nanoparticles (AgNP). Antioxidants present in rapeseed and its by-product extracts reduced cerium(IV) ions to red-purple solutions of cerium oxide nanoparticles at pH 5.6. The influences of time, temperature, pH, and the concentration of the cerium(IV) sulfate solution on cerium oxide nanoparticle generation were estimated. The average AC of the studied extracts of real samples ranged between 1037 and 3012 μmol sinapic acid (SA) 100 g^?1 and 3859–12,534 μmol SA 100 g^?1 for CeONP and AgNP assays, respectively. There is significant, positive correlation between the AC of the examined extracts determined by both analytical methods (r?=?0.8189). Satisfactory values of relative standard deviation (RSD?=?1.2–3.9 %) and recovery (95.8–103.3 %) demonstrate a good precision and accuracy of the novel CeONP method for the AC analysis of rapeseed and its by-products.

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Graphical Abstract Reaction mechanism of cerium ions reduction by sinapic acid was proposed for a new cerium oxide nanoparticle-based (CeONP) method

     

Microsecond nonlinear model predictive control for DC-DC converters

In this paper, we present a novel nonlinear model predictive control (NMPC) formulation for the transient control of a DC-DC converter. We demonstrate that a real-time implementation of the proposed NMPC scheme using the PANOC solver can be efficiently applied to control DC-DC converters in the microsecond range. Moreover, an embedded, code-generated version of PANOC can be implemented using microcontrollers or digital signal processors. The algorithm is incorporated in the transient simulator of PWM DC-DC converters, and the operation of the simulator on the boost converter's example is presented, comparing the performance of our NMPC-controller with that of a classical PID controller. The operation of the boost converter controlled using the proposed NMPC algorithm is validated experimentally.     

Magnetocaloric effect in La<Subscript>1–<Emphasis Type="Italic">x</Emphasis></Subscript>Ca<Subscript><Emphasis Type="Italic">x</Emphasis></Subscript>MnO<Subscript>3</Subscript> for <Emphasis Type="Italic">x</Emphasis> = 0.3, 0.35, and 0.4

We present systematic studies of the magnetocaloric properties of the polycrystalline La_1−x Ca _x MnO₃ system for x = 0.3, 0.35, and 0.4 near a second-order phase transition from a ferromagnetic to a paramagnetic state. The crystal structure of the studied manganites was shown to be in good agreement with previous reports. The value of the magnetocaloric effect has been determined from the measurement of magnetization as a function of temperature and external magnetic field. The maximum entropy change detected in La_0.7Ca_0.3MnO₃ at a field of 2 T reaches 8 J/kg K which exceeds that of gadolinium. In all studied samples, the paramagnetic–ferromagnetic transition is very narrow but no hysteresis is observed and the transitions are identified as second-order ones. The phase transition in La_0.7Ca_0.3MnO₃ appears to be almost of first-order.     

Radiochemical indoor environment and possible health risks in current building technology

Tremendous work of civil and environmental engineering has been focused on development of sustainable buildings. From economical and ecological viewpoint, this approach is a significant step forward, but the microenvironment created in such living surroundings may present a complex radiochemical setting, which could be a threat to the health of its occupants. This paper gives overview about levels of indoor radon, insight in risks related with radioactivity of fly ash and zircon, current application of nanoparticles and concrete additives in buildings and their possible impact on human health. As construction engineering is current producer of almost 50% of waste encouragement of incorporation of toxic and radioactive agents in buildings could in future demand redefinition of building construction waste as hazardous and special waste disposals. Collaboration between governmental and non-governmental bodies, manufacturers, scientific institutions, and chartered engineers is needed in order to find balance between quality of indoor air, and to enable maintaining of high health standards by application of non-toxic or non-carcinogenic building materials that meet energy efficiency, building structure stability and security requirements.     

Why do overqualified incumbents deviate? Examining multiple mediators.

In the modern marketplace, especially when unemployment is high, more and more Americans find themselves overqualified (i.e., possessing more competencies than the job requires). Using and extending person-environment fit theory and the stressor-emotion model of counterproductive work behaviors (CWBs), we examine whether overqualified employees are more likely to display CWBs than employees who feel their positions match their qualification levels. Further, we examine why overqualified employees may behave in counterproductive ways and compare the empirical viability of several theoretically derived competing mediators. Based on data from a sample of full-time employees (n = 215), we found that consistent with the theoretical frameworks, overqualified incumbents display nondesirable counterproductive work behaviors because they become cynical about the meaningfulness of their activities. We further show that although poor person-job fit or inadequate psychological contracts can motivate such misbehavior, cynicism dominates as a reason for why overqualified employees engage in counterproductive work behaviors. (PsycINFO Database Record (c) 2011 APA, all rights reserved)