Growth and characterization of an organic nonlinear optical material: l-alanine alaninium nitrate

l-alanine alaninium nitrate (LAAN), an organic nonlinear optical material was grown by slow evaporation technique at room temperature from its aqueous solution at pH value of 2.5. As grown single crystals were characterized for its spectral, thermal, linear and second order nonlinear optical properties. LAAN crystallizes in monoclinic system with space group P₂₁ and cell parameters a = 7.846 Å, b = 5.431 Å, c = 12.806 Å and β = 94.65°. The mode of vibrations of different molecular groups present in LAAN were identified by FTIR studies. The thermal behaviour of the crystals has been investigated using thermogravimetry (TG) and differential thermal analysis (DTA), which indicates that the material does not decompose before melting. Transmittance spectrum reveals that the crystal has a low UV cut-off of 320 nm and has a good transmittance in the entire visible region. NLO property of the crystal was confirmed by Kurtz SHG powder technique.     

Extinction as a function of magnitude and percentage of food or sucrose reward.

64 male hooded rats in 8 groups were trained to run an alleyway and extinguished. For groups given food rewards, extinction performance was dependent on an interaction of the magnitude and percentage of reward in acquisition: in consistently reinforced Ss, large rewards led to slower running in extinction, but in partially reinforced Ss, large rewards led to faster running. With sucrose as the reward, however, large rewards (higher concentration) led to faster running in extinction irrespective of the schedule of reinforcement. These differences between food and sucrose are discussed in terms of frustration theory and sequential theory. The simplest interpretation, within the context of sequential theory, is to assume that different concentrations of sucrose, although differing in their reinforcing effects, do not produce discriminably different aftereffects. (French summary) (21 ref.) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Application of AFM from microbial cell to biofilm

Atomic Force Microscopy (AFM) has proven itself over recent years as an essential tool for the analysis of microbial systems. This article will review how AFM has been used to study microbial systems to provide unique insight into their behavior and relationship with their environment. Immobilization of live cells has enabled AFM imaging and force measurement to provide understanding of the structure and function of numerous microbial cells. At the macromolecular level AFM investigation into the properties of surface macromolecules and the energies associated with their mechanical conformation and functionality has helped unravel the complex interactions of microbial cells. At the level of the whole cell AFM has provided an integrated analysis of how the microbial cell exploits its environment through its selective, adaptable interface, the cell surface. In addition to these areas of study the AFM investigation of microbial biofilms has been vital for industrial and medical process analysis. There exists a tremendous potential for the future application of AFM to microbial systems and this has been strengthened by the trend to use AFM in combination with other characterization methods, such as confocal microscopy and Raman spectroscopy, to elucidate dynamic cellular processes. SCANNING 32: 134–149, 2010. © 2010 Wiley Periodicals, Inc.     

Xanthohumol induces apoptosis in cultured 40-16 human colon cancer cells by activation of the death receptor- and mitochondrial pathway

Xanthohumol (XN) is one of the major prenylflavonoids found in hop cones (Humulus lupulus L.). In this study, we investigated the cell growth inhibitory potential of XN on cultured human colon cancer cells. Cell proliferation was measured by sulforhodamine B staining. Poly(ADP-ribose)polymerase (PARP) cleavage, activation of caspases-3, -7, -8, and -9, and Bcl-2 family protein expression were detected by Western blot analyses. XN significantly reduced proliferation of the HCT 116-derived colon cancer cell line 40--16. Half-maximal inhibitory concentrations decreased from 4.1 microM after 24 h treatment to 3.6 and 2.6 microM after 48 and 72 h incubation, respectively. Treatment with 15 microM XN for 48 h and with 5 microM for 72 h led to the detection of the cleaved 89 kDa fragment of 116 kDa PARP as an indication of apoptosis induction. Concomitantly, we observed activation and cleavage of the effector caspases-3 and -7, induced by activation of the initiator caspases -8 and -9. Expression of anti-apoptotic Bcl-2 was down regulated when the cells were treated with XN for 48--72 h. We conclude that induction of apoptosis by downregulation of Bcl-2 and activation of the caspase cascade may contribute to the chemopreventive or therapeutic potential of XN.