Search results for "Generation"
showing 10 items of 3050 documents
Molecular and kinetic properties of lactate dehydrogenase in the degenerating peripheral nerve
1966
Abstract Electrophoretic and catalytic studies have been carried out on lactate dehydrogenase of normal and transected sciatic nerves of the rat. Lactate dehydrogenase of the intact nerve exhibits an almost even distribution of activity among its component iso-enzymes. The complete transection of the nerve is responsible for a deep and immediate shift of the enzyme towards the so-called muscle type pattern. Seven days after the nerve section the percentage activity of iso-enzyme 5 is almost three times higher than in the intact nerve. After a short lag period lactate dehydrogenase specific activity (activity/mg protein) undergoes a sharp decrease in transected nerves. The return of the elec…
Potential use of new diphenylurea derivatives in micropropagation of Capparis spinosa L.
2011
A protocol for in vitro multiplication of caper (Capparis spinosa L. subsp. rupestris) from nodal segments collected from mature plants was developed. For shoot multiplication, one auxin (indol-3-butyric acid, IBA) and cytokinins of two different classes were used: the N6-substituted adenine derivatives 6-benzylamino purine (BAP), and the two synthetic phenylurea derivatives N-phenyl-N′-benzothiazol-6-ylurea (PBU) and N-phenyl-N′-(1,2,3-thidiazol-5-yl) urea (thidiazuron, TDZ). Maximum shoot production was achieved from explants cultured with the adeninic cytokinin BAP (4 μM) and the auxin IBA (0.5 μM). New shoots longer than 1 cm were used for rooting. To induce root formation, three auxins…
Electron crystallography and organic materials with non-linear optical properties
1999
Results of electron microscopic studies of crystal structures of a number of bis-benzylidene cyclohexanones are presented. It is shown that some of these compounds are efficient crystalline non-linear optically active (NLO) chromophores with second harmonic generation (SHG) properties. Appropriately functionalized chromophores of this type can be used as a polycondensation comonomer to produce partly crystalline main-chain NLO-active polymers. Electron diffraction crystal structural data, obtained for very small crystals, allowed us to get reasonable estimations of macroscopic crystal NLO-coefficients, relating quantum-chemically calculated molecular first hyperpolarizability components to …
Oxidative stress and mitochondrial failure in the pathogenesis of glaucoma neurodegeneration
2015
This review focuses on oxidative stress and mitochondrial failure for understanding mechanisms of optic nerve damage in primary open-angle glaucoma. The chapter shows scientific evidence for the role of mitochondrial disbalance and reactive oxygen species in glaucoma neurodegeneration. Mitochondria regulate important cellular functions including reactive oxygen species generation and apoptosis. Mitochondrial alterations result from a wide variety of damaging sources. Reactive oxygen species formed by the mitochondria can act as signaling molecules, inducing lipid peroxidation and/or excitotoxicity with the result of cell lesion and death. Antioxidants may help to counteract oxidative stress…
Relaxation of electron-hole pairs and scintillation mechanism in alkali halide crystals
1997
Abstract The mechanism of the ionizing radiation energy transfer from host lattice to luminescence centers is discussed taking into account the results of the recent experimental investigations of electron-hole pair relaxation in alkali iodide crystals. The high scintillation yield in CsI-Tl, CsI-Na and partially in Nal-Tl crystals is explained by the process of the motion and capture of a one-center self-trapped exciton by impurity ions.
Modulation of Fatty Acid Patterns During Protoplast Isolation
1983
Protoplast isolation and regeneration is known from numerous plant species (Binding et al. 1). But there are plant species which show very unconstant regeneration or no reaction at all, even if the isolation showed high viability of the protoplasts. Does this lacking response only depend on medium composition and effectors or are there other unknown conditions? The procedure of protoplast isolation and the use of strong hypertonic media is a dramatic disturbance of cell metabolism and might be a stress situation, which cannot be overcome by the cell. Fleck et al. (2) reported “osmotic-stress proteins” in Nicotiana sylvestris protoplasts and Kaiser et al. (3) showed a remarkable influence of…
Stability of the functional NLO polymers–optically induced depoling of the DMABI molecules in sPMMA matrix
2008
Abstract Low polar order (PO) stability is the major problem of the polymer materials for nonlinear optical (NLO) applications. In this contribution we will show the results of PO stability investigations in the corona poled 3 wt.% DMABI + sPMMA guest–host system. Influence of the poling temperature on the building and stability of the polar order in the system will be presented. To characterize the stability, PO destruction has been caused by high intensity light. Polar order stability characteristics were obtained from the sample second harmonic generation intensity (SHI) time decays. We have found that the decay signal is the best fit to the sum of two exponentials. Several physical mode…
<title>All-optical poling of DMABI molecules in a polymer matrix</title>
2005
Many organic compounds in solid state have nonlinear optical properties due to the orientation of the molecules in a polymer matrix. In this work, all-optical poling and second harmonic generation in a composition consisting of 1 mass% of N,N-dimethylaminobenzylidene 1,3-indandione (DMABI) compound in poly(methyl methacrylate) (PMMA) matrix were studied. Thin films were prepared by solvent casting. The 1.064-μm fundamental and 532-nm second harmonic wavelengths of a Nd:YAG laser were used. It is shown that DMABI molecules can be oriented by the method of all- optical poling, and that the process is related to the photoinduced switching between two equally stable states of the molecule.
<title>Nonlinear optical properties of some indandione-1,3 pyridinium betaine derivatives</title>
1997
In this paper nonlinear optical properties of indandione-1,3 pyridinium betaine (IPB) molecule and its novel amphiphilic derivatives have been studied. Hyper-Rayleigh scattering (HRS) has been used as a direct and accurate tool to determine effective hyperpolarizability (beta) of IPB derivatives dissolved in chloroform. Evaluation of hyperpolarizability gives an averaged values of (beta) from 140 multiplied by 10-30 to 450 multiplied by 10-30 esu. Disordering of molecular orientation for multilayer Langmuir-Blodgett films of compound C17-IPB has been studied by SHG techniques and discussed for different film thickness. It has been observed that orientation degree of the Z-type molecular str…
An improved molecular design of obtaining NLO active molecular glasses using triphenyl moieties as amorphous phase formation enhancers
2012
New molecular design of obtaining molecular glasses has been developed by linking triphenylmethyl moieties to chromophore core by flexible C-C bridge. Compounds capable of forming stable amorphous phase with good optical quality have been acquired with increased chemical and thermal sustainability compared to the previously reported design. NLO activity of compounds has been measured after corona discharge polling. Compared to previously synthesized trityloxy fragment containing compounds increase of d 33 coefficient by up to 17 times was achieved for the same chromophore core containing compounds.