Photochemical synthesis of benz[h]isoquinolines

The synthesis of benz[h]isoquinolines has been achieved using a highly convergent photochemical method. The approach presented provides ready access to biologically active compounds and building blocks not readily available through other methods.     

Pretreatment of Reed by Wet Oxidation and Subsequent Utilization of the Pretreated Fibers for Ethanol Production

Common reed (Phragmites australis) is often recognized as a promising source of renewable energy. However, it is among the least characterized crops from the bioethanol perspective. Although one third of reed dry matter is cellulose, without pretreatment, it resists enzymatic hydrolysis like lignocelluloses usually do. In the present study, wet oxidation was investigated as the pretreatment method to enhance the enzymatic digestibility of reed cellulose to soluble sugars and thus improve the convertibility of reed to ethanol. The most effective treatment increased the digestibility of reed cellulose by cellulases more than three times compared to the untreated control. During this wet oxidation, 51.7% of the hemicellulose and 58.3% of the lignin were solubilized, whereas 87.1% of the cellulose remained in the solids. After enzymatic hydrolysis of pretreated fibers from the same treatment, the conversion of cellulose to glucose was 82.4%. Simultaneous saccharification and fermentation of pretreated solids resulted in a final ethanol concentration as high as 8.7 g/L, yielding 73% of the theoretical.     

NO-bound myoglobin: structural diversity and dynamics of the NO ligand

We used femtosecond infrared polarization spectroscopy and density functional theory in a study on the key signaling molecule nitric oxide (NO) bound to myoglobin. Our results show that after photolysis, a substantial fraction of NO recombines within the first few picoseconds. We discovered that the diatomic ligand is severely tilted in the protein and present evidence that the Fe-NO moiety can sample a wide range of off-axis tilting and bending conformations.     

Representation of feedback operators for parabolic control problems

In this paper we present results on existence and regularity of integral representations of feedback operators arising from parabolic control problems. The existence of such representations is important for the design of low order compensators and in the placement of sensors. This paper extends earlier results of J. A. Burns and B. B. King to problems with spatial dimensions.     

CE: a useful analytical tool for the characterization of Maillard reaction products in foods

The Maillard reaction (MR) is a complex series of nonenzymatic reactions between reducing compounds and amines, amino acids, peptides, or proteins that play an important role in the formation of flavors and colors in foods during processing and storage. Also, the antioxidant properties of some Maillard reaction products (MRP) was an additional benefit reported. On the other hand, these reactions decrease the nutritional quality of foods and may result in the formation of toxic MRP. Although, research to assess the risks and benefits associated with the consumption of MRP in the diet is still awaiting for new analytical methodologies to be developed. Structural characterization of MRP has been very challenging due to the chemical diversity of these compounds which present a wide range of polarities and molecular weights, making analyses difficult. CE is a technique that has gained popularity for the separation of complex mixtures that have otherwise proved difficult to analyze. Thus, the purpose of this overview is to give the reader an appreciation of some of the CE analytical developments on the analysis of MRP in model systems and foods, and to address the potential of CE on the characterization of this complex group of compounds.     

Boolean topological graphs of semigroups: the lack of first-order axiomatization

The graph of an algebra A is the relational structure G(A) in which the relations are the graphs of the basic operations of A. For a class ?? of algebras let G(??)={G(A)∣A∈??}. Assume that ?? is a class of semigroups possessing a nontrivial member with a neutral element and let ? be the universal Horn class generated by G(??). We prove that the Boolean core of ?, i.e., the topological prevariety generated by finite members of ? equipped with the discrete topology, does not admit a first-order axiomatization relative to the class of all Boolean topological structures in the language of ?. We derive analogous results when ?? is a class of monoids or groups with a nontrivial member.     

Synthesis of substituted 4-(1H-indol-6-yl)-1H-indazoles as potential PDK1 inhibitors

The development of a preparative route to a series of novel 4-(1H-indol-6-yl)-1H-indazole compounds as potential PDK1 inhibitors is described. The synthetic strategy centres on the late-stage Suzuki cross-coupling of N-unprotected indazole and indole fragments. The use of a monoligated palladium catalyst system was found to be highly beneficial in the cross-coupling reaction. The indazole and indole fragments were constructed by diazotisation/cyclisation and S_NAr/reductive cyclisation sequences, respectively.     

Three-dimensional orientation of the Qy electronic transition dipole moment within the chlorophyll a molecule determined by femtosecond polarization resolved VIS pump-IR probe spectroscopy

Chlorophyll a (Chl a) is the most abundant pigment on earth. In all plants, algae, and cyanobacteria, it plays a pivotal role as an antenna and reaction center pigment in the primary steps of photosynthesis. In the past, a true three-dimensional (3D) experimental determination of the Qy electronic transition dipole moment orientation could not be obtained. With combined femtosecond polarization resolved VIS pump-IR probe experiments and theoretical calculations of the infrared transition dipole moments (tdm's) in the electronic ground state, we determined the 3D orientation of the Qy electronic tdm of Chl a within the molecular structure. Polarization resolved experiments provided angles of the Qy electronic tdm with three different infrared tdm's, whose orientations within the molecular structure were taken from our theoretical calculations. The orientation of the Qy tdm results from the intersection of all three angles and was found to have an angle of (78 +/- 3)degrees with the x-axis, (12 3)degrees with the y-axis, and (86 +/- 2)degrees with the z-axis.     

Identification of individual DNA molecule of Mycobacterium tuberculosis by nested PCR-RFLP and capillary electrophoresis

The improvement of sensitivity and differentiation in rapidly identifying a small amount of mycobacteria in sputum has significant implications for reducing tuberculosis transmission. We previously applied the conventional PCR and capillary electrophoresis (CE) to establish the restriction fragment length polymorphism (RFLP) pattern of mycobacterial 65-kDa heat shock protein (hsp65) gene from colony specimens. However, the previous analysis did not provide enough sensitivity for sputum specimens in which the limitation of analysis might be hindered by PCR inhibitors and primer-dimers formation during amplification. In the current study, nested PCR (nPCR) had been redesigned for PCR-RFLP analysis (PRA) of mycobacterial hsp65 gene using CE. The results show both Mycobacterium tuberculosis complex and mycobacteria other than tuberculosis could be identified in the presence of PCR inhibitors. The interference due to primer-dimers was also minimized. Based on the Poisson distribution, the repeatability of single DNA molecule detection was greatly affected by sampling probability and might be improved significantly by increasing the sample loading. The PRA using nPCR and CE is not only able to detect the individual mycobacterial DNA molecule but also potentially differentiate the species.     

Nanocaging Rose Bengal to Inhibit Aggregation and Enhance Photo-induced Oxygen Consumption†

Photosensitized crosslinking of proteins in tissues has many medical applications including sealing wounds, strengthening tissues, and beneficially altering tissue properties. Rose Bengal (RB) is used most frequently as the photosensitizer but is not as efficient as would be desired for broad utilization in medicine. Aggregation of RB, at the high concentrations used for medical treatments, decreases the yield of singlet oxygen, which mediates protein crosslinking. We hypothesized that nanocages that sequester RB would inhibit self-association, increasing photosensitization efficiency. We tested cucurbituril and cyclodextrin nanocages, demonstrating that hydroxypropyl-functionalized cyclodextrins are most effective in inhibiting RB aggregation. For these RB/cyclodextrin solutions, we investigated the effect of nanocaging on the photobleaching and oxygen consumption kinetics under 530 nm LED light in aqueous phosphate-buffered solutions. At 100 μm RB, the initial oxygen consumption rates increased by 58% and 80% compared with uncaged RB for the β and γ (2-hydroxypropyl) cyclodextrins, respectively. For 1 mm RB, the enhancement in these rates was much greater, about 200% and 300%, respectively. In addition, at 1 mm RB these two cyclodextrins increased the RB photobleaching rate by ~20% and ~75%. These results suggest that nanocages can minimize RB aggregation and may lead to higher-efficiency photo-medical therapies.