Photo-physical properties and amplified spontaneous emission of a new derivative of fluorescein

The synthesis of new high-performance dyes and the implementation of new ways of incorporating the organic molecules into the solid host matrices have produced a great deal of activity in the field of solid-state dye lasers. In this article, the new laser dye, 2-(6-allyl-3-oxo-3H-xanthen-9-yl)-benzoic acid ethyl ester [AXBE] has been synthesized, and its chemical structure was confirmed by ¹H NMR, ¹³C NMR, IR and elemental analysis. This new dye was covalently bonded with methyl methacrylate (MMA) and 2-hydroxy ethyl methacrylate (HEMA) copolymer backbone and evaluated as the active medium of the solid-state laser dye. Its optical properties were experimentally investigated. Amplified spontaneous emission (ASE) and photostability were studied by pumping the dye sample with 355 nm (8 ns) pulsed Nd-YAG laser.     

Application of Chitosan-Based Biomaterials for Blood Vessel Regeneration

Summary: Vascular diseases are the leading cause of morbidity and mortality in the western world. Autologous vessels remain the standard for coronary grafting and peripheral bypass surgery; however, their availability in patients can be limited. Therapeutic angiogenesis using growth factors, genes, or progenitor cells has been given considerable scientific attention over the last decade, but has not yet provided a definitive clinical benefit. Biomaterials could be developed to protect protein, DNA and cells against hostile conditions. Chitosan, a natural polymer of glucosamine and N-acetyl glucosamine, has been widely studied in tissue engineering due to its biocompatibility, biodegradability, and muco-adhesive and antimicrobial properties. Notably, the application of chitosan has been gaining attention in the vascular field due to its structural similarity to glycosaminoglycans, which are components of a tissue's extracellular matrix. In this review, chitosan-based materials, and their use in tissue engineered blood vessels, and as protein, gene and cell vectors for angiogenic therapy are discussed.     

Isomorphism of Modular Group Algebras of p-Mixed Abelian Groups

Let A be a torsion-free abelian group and F a free subgroup of A. We prove that if A/F is a reduced p-group and A/(F + C) is reduced for every p-pure subgroup C of A, then A is free.

Let KG be the group algebra of an abelian group G over a field K of prime characteristic p. Denote by S(KG) the p-component of the group V(KG) of normalized units of KG (of augmentation 1). Let H be an arbitrary group and KH ? KG as K-algebras. We prove the following. First, assume that G is a splitting group, the p-component G _p of G is simply presented, and the field K is perfect. Then H _p  ? G _p . If, in addition, G is p-mixed, then G _p is a direct factor of S(KG), and G is a direct factor of V(KG), each with the same simply presented complement. Secondly, we introduce a class of special p-mixed abelian groups and prove that, if G belong to this class, then any group basis of the group algebra KG splits. Besides, H is p-mixed and splits. Thirdly, if G is a special p-mixed abelian group and G _p is a reduced totally projective p-group, then H ? G. These results correct some essential inaccuracies and incompleteness in the proofs of results in this direction of Danchev [3-8 Danchev , P. V. ( 1998 ). Isomorphism of commutative group algebras of mixed splitting groups . Compt. Rend. Acad. Bulg. Sci. 51 : 13 – 16 . Danchev , P. V. ( 2000 ). Isomorphism of modular group algebras of totally projective abelian groups . Communications in Algebra 28 : 2521 – 2531 . Danchev , P. V. ( 2001 ). On a question of W. L. May concerning the isomorphism of modular group algebras . Communications in Algebra 29 : 1953 – 1958 . Danchev , P. V. ( 2001 ). Normed units in Abelian group rings . Glasg. Math. J. 43 : 365 – 373 . Danchev , P. V. ( 2002 ). Invariants for group algebras of splitting abelian groups with simply presented components . Compt. Rend. Acad. Bulg. Sci. 55 : 5 – 8 . Danchev , P. V. ( 2004 ). A note on the isomorphic modular group algebras of abelian groups with simply presented p-components . Compt. Rend. Acad. Bulg. Sci. 57 : 13 – 14 . ].     

Combined Photoredox/Enzymatic C−H Benzylic Hydroxylations

Chemical transformations that install heteroatoms into C?H bonds are of significant interest because they streamline the construction of value‐added small molecules. Direct C?H oxyfunctionalization, or the one step conversion of a C?H bond to a C?O bond, could be a highly enabling transformation due to the prevalence of the resulting enantioenriched alcohols in pharmaceuticals and natural products,. Here we report a single‐flask photoredox/enzymatic process for direct C?H hydroxylation that proceeds with broad reactivity, chemoselectivity and enantioselectivity. This unified strategy advances general photoredox and enzymatic catalysis synergy and enables chemoenzymatic processes for powerful and selective oxidative transformations.     

Cortical sensitivity to periodicity of speech sounds

Previous non-invasive brain research has reported auditory cortical sensitivity to periodicity as reflected by larger and more anterior responses to periodic than to aperiodic vowels. The current study investigated whether there is a lower fundamental frequency (F0) limit for this effect. Auditory evoked fields (AEFs) elicited by natural-sounding 400 ms periodic and aperiodic vowel stimuli were measured with magnetoencephalography. Vowel F0 ranged from normal male speech (113 Hz) to exceptionally low values (9 Hz). Both the auditory N1m and sustained fields were larger in amplitude for periodic than for aperiodic vowels. The AEF sources for periodic vowels were also anterior to those for the aperiodic vowels. Importantly, the AEF amplitudes and locations were unaffected by the F0 decrement of the periodic vowels. However, the N1m latency increased monotonically as F0 was decreased down to 19 Hz, below which this trend broke down. Also, a cascade of transient N1m-like responses was observed in the lowest F0 condition. Thus, the auditory system seems capable of extracting the periodicity even from very low F0 vowels. The behavior of the N1m latency and the emergence of a response cascade at very low F0 values may reflect the lower limit of pitch perception.     

In vitro evaluation of potential complexation between bovine insulin and bovine serum albumin

The objective of this study was to examine the possible binding of bovine insulin (BI) with bovine serum albumin (BSA) to form a new potential diabetogenic irreversible complex protein. Several preparations of BSA and BI were prepared. Both capillary electrophoresis and spectrophotometric analysis were undertaken to test the possibility of complexation between BI and BSA. HPLC was used to test whether the potential complex of BI and BSA is reversible or irreversible. The optimum deviation between the real and calculated absorbances was observed at a BI/BSA ratio of 2. Moreover, the migration time of BI decreased substantially with increasing ratio of BI to BSA until it became almost constant at equal molar ratio of BI/BSA. While the majority of the 2:1 BI–BSA sample detached during the HPLC analysis, which confirms the reversible character of BI–BSA binding, the HPLC chromatogram also emphasizes the formation of an irreversible complexation between the two proteins. This study provides evidence of the formation of reversible and irreversible new BI–BSA complexes under physiological conditions. This highlights the importance of examining the possible diabetogenicity of BI–BSA complex in genetically susceptible people. Copyright © 2013 John Wiley & Sons, Ltd.